Making air bags work on G machine?

[BRIAN]

After going to a lot of shows and having my car passed up to evrything that had air bags and 20's I guess I am going new route on next project. Slammed and big wheels = big trophies and money.

I know nothing about air bags. I sthere anyway to determine their spring weight at the different levels? I know it would have to be set at certain dedicated driving level to reach optimum handling. That and the side to side issue from what I understand has been addressed with the new computer set ups.

Question is how does one determine the rate on the bags? Is there such a thing?

[Travis B]

I don't know if there is a determined rate i'm sure air ride tech has that info.....but in a sense the rate is adjustable! Lets say a 2600 series bag dual convoluted stlye for the front of your car! install hieght is 5-5.5in
compressed is 3in and max hieght is 8in! So at that 5-5.5 height range you can play with the air pressure lets say 5-10psi and change the spring rate! Mounting location is also a factor on how the bag reacts....Air bags can be made to handle!

Call [email protected] tell him
Kenny Davis hot rods sent you! :bananna2:

I am building a 64 chevelle right now that will be on air....I think it should handle pretty well, we'll see

[cad]

I was talking to a friend last nite with a 1970 Nova that is riding on air bags, front and rear, with 18s and 20s.
He said that his car handles awesome, and the ride is phenomenal.
Unfortunately, I dont know any of the specs at this time.
Click here for a pic... (http://photobucket.com/albums/a56/cdoukas/2005%20Des%20Moines%20Good%20Guys%20Hotrod%20Show/?action=view&current=DSC04575.jpg)

[MuscleRodz]

I asked Tony a bunch of questions about that and although they have not got it to an exact science it is working. They are basically using a smaller bag and blowing it up to its travel limit. Then they are adjusting "spring rate" by adding or removing pressure and not changing ride height with the bag at its limit. This is the only way to seperate ride height from spring rate that I can see with air. The trick to this is making sure the shock travel is not at its limit with the bag inflated. It must still have a few inches of travel to operate. Then just dial the shock firmness up and go racing. This is what I got from our conversation and I am not sure it is exact but what I remember how it worked in theory.

Mike

[cad]

Another friend that I was talking to last nite said it is critical that independent air supply lines are installed (ie, a 4 corner system), or you will have an unsafe ride, due to "air bounce" between the 2 sides.
Plus, the monitor for air pressure at each corner should be observed at all times, therefore, he recommended to NOT hide the controller.

[Travis B]

Another friend that I was talking to last nite said it is critical that independent air supply lines are installed (ie, a 4 corner system), or you will have an unsafe ride, due to "air bounce" between the 2 sides.
Plus, the monitor for air pressure at each corner should be observed at all times, therefore, he recommended to NOT hide the controller.


4way is a must....the ride pro-e kit is what we put on just about everything!

[BRIAN]

I will make some calls but I feel the above answers are what I am going to get. Are there that many size bags where the rates in a bag at it's limits can be swapped out for say one at 90%, 75%, etc?
What about simply putting it in a spring tester at varying pressures but at the same height ?

[ViperBlue68]

I was talking to a friend last nite with a 1970 Nova that is riding on air bags, front and rear, with 18s and 20s.
He said that his car handles awesome, and the ride is phenomenal.
Unfortunately, I dont know any of the specs at this time.
Click here for a pic... (http://photobucket.com/albums/a56/cdoukas/2005%20Des%20Moines%20Good%20Guys%20Hotrod%20Show/?action=view&current=DSC04575.jpg)

Thats a sweet looking nova :cool: I've thought about bags but i'd be nervous about ripping a bag and the car goin down at high speed....have had hydraulics when I was younger and blew a cylinder liftin while i was on the road doin 45 not a good thing to say the least...

[Travis B]

Thats a sweet looking nova :cool: I've thought about bags but i'd be nervous about ripping a bag and the car goin down at high speed....have had hydraulics when I was younger and blew a cylinder liftin while i was on the road doin 45 not a good thing to say the least...

The only way you would hurt a bag is if
1.you to much pressure in the bag
2.If it was set up improperly and it was rubbing on itself or something!

Other than that Semi's use them for thousands upon thousands of miles

[Travis B]

I will make some calls but I feel the above answers are what I am going to get. Are there that many size bags where the rates in a bag at it's limits can be swapped out for say one at 90%, 75%, etc?
What about simply putting it in a spring tester at varying pressures but at the same height ?


There are several different bags for various app's
Air ride lists a bunch of them in there catalog and i'm sure they have some more!

[Beige]

Thats a sweet looking nova :cool: I've thought about bags but i'd be nervous about ripping a bag and the car goin down at high speed....have had hydraulics when I was younger and blew a cylinder liftin while i was on the road doin 45 not a good thing to say the least...

The front spring on my aunts Windstar broke and put a hole in the tire. Luckily it was parked at the time but if it wasn't... I'd take an airbag blowing out over that.

[Steve Chryssos]

There are several different bags for various app's
Air ride lists a bunch of them in there catalog and i'm sure they have some more!

Yeah, but I don't see how one can convert the data on their site to match traditional metal springs?? :help:

[Steve Chryssos]

For example I know my coil-overs, at ride height have a 13.875" eye to eye length. And I know I have about 950lbs over each front wheel.

I would imagine that if i wanted to install air rides on my car, I would need to know my car's corner weights, installed length at ride height, motion ratios, etc. Stuff like that. Then, I'd wanna to know how to convert the steel spring rates in my car now over to psi. I suppose you'd want close to max psi at that static ride height for a handling car? Then, at what rate does the psi increase as you approach bump? Is it linear like my coil springs? What should I do about sway bars? Stiffer than normal?

Inquiring minds wanna know.
/Steevo

[Travis B]

For example I know my coil-overs, at ride height have a 13.875" eye to eye length. And I know I have about 950lbs over each front wheel.

I would imagine that if i wanted to install air rides on my car, I would need to know my car's corner weights, installed length at ride height, motion ratios, etc. Stuff like that. Then, I'd wanna to know how to convert the steel spring rates in my car now over to psi. I suppose you'd want close to max psi at that static ride height for a handling car? Then, at what rate does the psi increase as you approach bump? Is it linear like my coil springs? What should I do about sway bars? Stiffer than normal?

Inquiring minds wanna know.

/Steevo

very good questions......unfortunatly I don't know the answers to, I will talk with tony and see if he can respond..I know he use to post here but haven't seen him on in awhile!

[Chevy350]

Here's something similar, and some of Tony's answers:
https://www.pro-touring.com/forum/showthread.php?t=4613

[Steve Chryssos]

Better, but not specific enough. At least I know that small pressure changes make a big difference, but that post would not get me any closer to looking at a published air spring chart and making a proper selection. I realize that I could just call and get a part number. But I'd want to know how they arrived at that part number.

Perhaps some of our suspension experts will chime in and help Brian gather data that will help him ask the right questions. And gather data as though he were shopping for metal springs. Then Air Ride can show us the science behind converting that data to air springs.

If we can get to that point, then the question of the air spring's progressive rate tendency comes up. Which brings us to shock and sway bar tuning with respect to air spring.

I'm just curious.

[Beige]

You could use the Ideal Gas Law to approximate the pressure changes in the bag at different ride heights. If I remember right it's inversely square to the change in volume.
However, you don't need to store all of the air in the bag, and you can use leverage to change the rate that the bag changes volume through full suspension travel. Of course, any extra stuff you add is going to rack up the cost as well.

[BRIAN]

Those are the questions I am looking to have answered.

Normally I set a car up with an approx spring rate and go up or down from there trying to not adjust the coil overs more than 1/2 inch. It is hard to make that cool look and a performance ride to work. I think most guys miss that whole idea and just crank up and down not caring about spring rates or crushing the spring..

I would be curious if anyone has simply inflated a bag to it's approriate ride height, one which would allow for the usual 2/3 compression and 1/3 rebound and see what it's rate is? I would assume this is possible. There would be a wider sweet spot I am sure but there has to be a figure somehow? They can't be usig the same bags on 4000lb and 2500lb cars?


As far as the loss in rate with the compression of the bag? I wouldn't even know where to start on that one.

Bags are here to stay and with the above info they would be easier to adapt to a car that is going to be driven hard. Even if they were low rates you could do the most horrible thing possible to most here and put larger bars to somewhat compensate?

I am off to Rhinebeck, if they are there I will ask if not I will place a call Monday for some answers.

[Mean 69]

You could use the Ideal Gas Law to approximate the pressure changes in the bag at different ride heights. If I remember right it's inversely square to the change in volume.

You could, but you have more variables than you think in this system, dynamically. PV = NRT is a pretty good place to start to try to harness this thing, but realize that in an air bag, the volume is not a constant, because the bag is deformable. At least, it'd better be!! As such, it is a bit harder to model than a rigid vessel as is typically the case for textbook examples: volume, will be a function of pressure, which affects pressure, which affects volume, and so on. It can be modelled, no doubt, but I'd bet it hasn't yet.

I'll be honest, I have never considered such a device for a springing medium in a performance application (i.e used on the track, not running to the store for more chips during half-time). I'm game for learning more about the dynamics and physics of the system, as long as responses can be explained with a reasonable technical explanation (sorry, "it feels really good just try it" is not an acceptable response, it may be true, but why???).

Most folks don't want to hear it, but the word "compromise" is probably the most important word in terms of performance suspension setups, you simply can't have it all simultaneously. Let the consumer beware.

Tech?
Mark

[Porterbuilt]

These are all questions that can be answered through scientific formulas and advanced calculations... but I am yet to find them! What I do know is that one part of me is addicted to air suspension (because of it's adjustability); and another part of me isn't satisfied unless my ride can handle like it's on rails! I have devised a solution that might be of help. I am currently building (for myself) a 57 Chevrolet Pickup that will be used to proto-type a few suspension configurations. I intend it to closely follow the pro-touring theme. I also intend it to handle well. I also intend for it to be air suspended at all four corners. Sounds like some contradicting statements. But I don't think it has to be. I will use the Shockwave by Air Ride Technologies at all four corners. I will design and build the upper mounts to be adjustable and or accept a coil-over. That way I can either spend time "tuning" the Shockwaves by playing around with its pressures and heights, and still being able to keep the suspension geometry in check; or I will unbolt the shockwaves and bolt in the appropriate coil-overs when I want to surprise people at the track.

[Steve Chryssos]

Hey, where'd they go? Didn't AirRide used to advertise on ProTouring.com? I just looked and I don't see their banner ads anywhere.

[62fairlane]

so does anyone have any good concept of how to design for a good handling car with a designed ride height? I was just planning on running a spacer block to adjust rideheight vs. firmness on the front and adjustable bag mounts on the rear (similar to a coil over setup)

[baz67]

One thing that I have not seen mentioned is heat. What happens to the rate when the shock heats up at the track? You will increase the rate and/or ride height due to the air volume increase with added heat. Both would be bad in that circumstance because they would make your chassis unpredictable and dynamic as racing/track conditions change.

If you have a release valve to check the added pressure how would air be added to the system when the shocks cool down. It seems this violates the K.I.S.S. theory by adding compications to the car.

Lets address the added weight an airbag system adds to a track car. How much do these things weigh anyway? One benifit would be a better fore/aft balance with all the pumps and tanks in the trunk.

IMHO, airbags are for the street and not the track, as of now.

[Travis B]

One thing that I have not seen mentioned is heat. What happens to the rate when the shock heats up at the track? You will increase the rate and/or ride height due to the air volume increase with added heat. Both would be bad in that circumstance because they would make your chassis unpredictable and dynamic as racing/track conditions change.

If you have a release valve to check the added pressure how would air be added to the system when the shocks cool down. It seems this violates the K.I.S.S. theory by adding compications to the car.

Lets address the added weight an airbag system adds to a track car. How much do these things weigh anyway? One benifit would be a better fore/aft balance with all the pumps and tanks in the trunk.

IMHO, airbags are for the street and not the track, as of now.

air bags are lighter than coil overs by far....The rest of the wieght is sprung weight(tanks, pump, valves, air line)!

[baz67]

air bags are lighter than coil overs by far....The rest of the wieght is sprung weight(tanks, pump, valves, air line)!

I understand that, but what about overall weight. Weight is still weight. Also, if one was worried about sprung mass why even mention 20s for wheels.

Another thing I thought of is what controls the freq. of the air bags? It is the shock that controls the freq. of the spring in a standard set-up. With the shock and spring as one unit(air bags), what stops the bag from bouncing from suspension movement?

Some real tech would be nice. I feel these are some valid issues to be answered for bags to be concidered for a high performance application.

[Mean 69]

I agree, Brian. I'd love to see a real explanation of what's really going on, beyond "try it, you'll love it."

Last time I looked, and I look very, very often, NO race car or team uses anything but a coil spring/damper combination. Of course, not everyone is concerned with performance, and that's okay, but if one is... Well, prove it to me, please.

Pneumatics can be a really compelling solution to lots of physical issues, but the control of the pressure, with all of the variables of temperature, volume, compression (gases are NOT perfect, so the ideal gas law needs to be tweaked, and can but?), and many other variables make it a complex issue to say the least. Going to the store for some chips? Well, that's not really a challenge. Going 9/10's at Willow Springs? Well....

I'd suggest an open track "challenge." All invited, level playing field.
M

[MuscleRodz]

I do believe Air Ride puts on some type of track/parking lot event at their show each year to show they do work. It would be nice if Tony would post up. He could answer alot of these questions. WIll they keep up with a typical coil/spring car? I don't think it is there yet either but they keep getting better and better.

Mike

[BrianP]

A couple of years ago you could order a CD from FirestoneIndustrial.com that included the juicy engineering type Data you that guys are looking for. I don't know if it's still available. Here's a sample Data Sheet showing the various height-pressure-force curves. I think where most people go wrong with this setup is that they just throw these things in and pump up the air to whatever ride height they need and then expect the ride to be great. They need to determine what pressure gives the best ride and then adjust the suspension attach points so they get that desired pressure at that height

[sinned]

A couple of years ago you could order a CD from FirestoneIndustrial.com that included the juicy engineering type Data you that guys are looking for. I don't know if it's still available. Here's a sample Data Sheet showing the various height-pressure-force curves. I think where most people go wrong with this setup is that they just throw these things in and pump up the air to whatever ride height they need and then expect the ride to be great. They need to determine what pressure gives the best ride and then adjust the suspension attach points so they get that desired pressure at that height
Actually, ride comfort is the very last thing anyone replying to this thread is interested in. Most of us don't just "throw" anything on a car and a lot have a pretty good idea what is involved with the actual engineering of a particular package...hence the request for hard tech.


Thanks for the input howver.

[BrianP]

OK, How about if we replace "best ride" with "desired firmness, stiffness or spring rate."

[sinned]

Better, but still doesn't help to answer the question of how exactly does bag air pressure/bag size/other factors convert to spring rate. The question is how can bags be used in a road course or very spirted driving experience effectively since the bag does not have a specific spring rate; also, how do the outside factors such as weather (temperature changes the bag pressure) affect the perceived rate? More importantly, is it even possible to convert X bag size with X pressure into a specific spring rate? It seems to me that all air bags are progressive springs which means that you cannot convert the bag pressure to a specific rate as it is always changing as the bag height changes.

[Travis B]

I do believe Air Ride puts on some type of track/parking lot event at their show each year to show they do work. It would be nice if Tony would post up. He could answer alot of these questions. WIll they keep up with a typical coil/spring car? I don't think it is there yet either but they keep getting better and better.

Mike


They had an open track event already this year I made a post about it.....Steve was the only one that responded...I think he said PHR was going to cover the event in an upcoming mag!

[Steve Chryssos]

https://static1.pt-content.com/images/noimg.gif

NOW THAT'S AN AIR SPRING!
"Adaptive Damping System" technology offers computer control of BOTH the air bellow and shock absorber. Both elements (shock and spring) feature resevoirs which the computer uses to compensate for pressure changes.

It's complicated and expensive. I've seen one of these. It's as big as a leg of lamb (though sprung mass is said to be lighter than a coilover or strut.) Until adaptive air springs exist in the aftermarket (and don't hold yer breath), I just do not see how passive air springs can offer comparable performance to a metal spring.

But that's okay. I would settle for knowing how to order the proper bellow for my specific application--not because I'm looking to buy, but because I wanna know if they know.

[Damn True]

I have a number of concerns surrounding air suspension that I have yet to see adressed.

a) How do the shocks react to heat. If I inflate my shocks at 6:30 in the morning and its 65deg in my garage, but 90deg at the track and then I drive the car and put more heat in the system? All of the changes in heat will affect the pressure and volume of air in the system. How does the system deal with that, if at all?

b) Damping. Position sensative? Speed Sensative? Insensative?

c) Adjustability. Can rate and ride height be adjusted independantly without moving mounting points?

[Tony@AirRideTech]

wow..... sorry that I have missedthis thread guys.... let me see if I can help you guys out a little further.
First off let me see if I can explain this a little better here..... Firestone makes literally hundres of different types of airsprings so shoosing the correct airspring, like choosing steel spring is critical. The critical part to choosing the correct airspring is going to be choosing one that is best going to match your suspension geometry, ride height, and vehicle weight. The hardest part to it is finding the one that will have the inclination of the spring rate match with the application that you are installing it in. The funny thing about an airspring is that the direct load within reason can vary heavily from application to application but the same airspring will actually be applicable. For example a guy building a small block powered British MG may very well use the same airspring that a guy building a big block powered Impala will use. The magic comes from knowing what the installed ride height of each individual so that you get the airspring within its preferred spring rate curve. The only notable difference between the two cars above would be the pressure that you are reading on the gauge. The pressure is basically a direct reflection of the amount of air it takes to acheive the correct amount of spring rate to effectively hold a given vehicle at its designed ride height.
Now once you have achieved ride height, making small pressure changes as little as 1-2 psi and up to 5psi either direction of your target height will effectively change the spring rate without changing the height of the vehicle. doing so would be like going from say a 200 to a 225 to a 250 to a 275 ect.... I think for the most part I have made mention of all of this before on these threads.... either way there we have it again...
Like mentioned above, looking at a dynamic spring rate chart for a specific airspring can be complex and exhausting because any given spring with display different characteristics and rates for every PSI change made. They are available though and Firestone does have these charts. Your best bet is to phone us, let us know what you have and we can go from there. We can help you select a spring and give you the designed ride height for your application. If you are wanting to truley boggle your mind, you can contact us or Firestone and get spring charts.
I will try to answer a few of the questions that I can remember from up top and if any of you guys have further questions or if I miss one... plug away and I will do my best.
The dynamics will not be effected by normal tempatures enough to be considered. When you are talking about the amount of PSI that we typically run in these applications, it will take an abnormal amount of tempature to effect pressure. I have only experienced a variable PSI one time and that was on a truck that was running a low pressure to obtain ride height to begin with and then the exhaust was blowing directly on the spring. So you would start the truck and as it heated up you would essentially release a few pounds of air to bring it back to spec.

[Damn True]

Tony,
Thanks for jumping in. You didn't touch upon my questions regarding damping or rate & ride height adjustability at all and Id appreciate it if you could address some important fixed issues.

Boyle's, Lussac's & Charles' laws cannot be avoided and I have a very hard time swallowing that the system is unnefected by changes in volume as a result of compression of the air spring and temprature as a result of environmental changes or as a result of compression.

Boyles law: P1 x V1 = P2 x V2
Lussacs law: P1/T1 = P2/T2
Charles law: V1/T1 = V2/T2

Combined gas law: (P1 x V1) / T1 = (P2 x V2) / T2

[Damn True]

Any response?

[Beige]

You could try using those formulas you posted.

[Damn True]

Not without knowing pressure, volume, compression ratio and operating vs static tempratures. I was hoping that the gentleman from air ride might reply with some actual technical data.

[darren@ridetech]

Damn True,

I posted this on another thread but figured I would throw it in here too.
As far as the temp. & pressures changes go, in theory that is all correct. But in reality the effects are so minute that one would never notice. If in fact there was a great temp. change that increased the psi a bit, just let a couple pounds out.

[Steve1968LS2]

They had an open track event already this year I made a post about it.....Steve was the only one that responded...I think he said PHR was going to cover the event in an upcoming mag!

I didn't get to go but Johnny did. He was pretty impressed with the overall feel and performance. There will be a Speed Reading deal on it for January.

There was no "testing" done that I know of, just seat-of-the-pants stuff. People I talked to got a favorable impression. I don't know if this system is meant for heavy duty most of the time track cars but for the average pt guy it seems more than capable. I would like to see hard data and testing with equipment done.

[Steve1968LS2]

Tony,
Boyle's, Lussac's & Charles' laws cannot be avoided and I have a very hard time swallowing that the system is unnefected by changes in volume as a result of compression of the air spring and temprature as a result of environmental changes or as a result of compression.

Boyles law: P1 x V1 = P2 x V2
Lussacs law: P1/T1 = P2/T2
Charles law: V1/T1 = V2/T2

Combined gas law: (P1 x V1) / T1 = (P2 x V2) / T2

I think he was trying to say that there is an effect but it is minimal. Since they run a high pressure an increase of a few PSI is minimal when look at in a percent increase or decrease.

Arn't all systems affected by heat to some degree? (gas shocks, oil shocks)

[Mean 69]

Yes, every mechanical system is affected by thermal issues. And from the reverse perspective, I think all that True and others (myself strongly included) are some tangible technical facts beyond the "it works really good" stuff that seems to come across so frequently (not a knock specifically on AirRide, more a comment on so many others that don't back up their claims with specific facts on WHY they work the way they do). They really may be on to something incredibly novel, and it may have some really interesting benefits that haven't been shown already.

Let's ask something basic, from a specific answer to this, I can probably back into an approximation (many others could too, I'd appreciate it, not too much free time to think these days) of a basic "spring rate" or at least some basis for things that are of interest. Take an application, your choice. What is the range of ride heights from fully down, to fully up? What is the pressure in the bag at full "up?" What is the corner weight on that end? If I place the ride height in the very center, what pressure is in the bag? If I lower the car 1" from that height, what is the corresponding pressure? If I raise one inch from the very center, what is the resulting pressure?

We stated a few months back that we would hold manufacturers/installers/dealers to a high standard in terms of explanation after the episode with the dude that knocked off Wayne's front stuff and threw claims like "my philosophy is that your car should handle like a go kart, flicking around turns, that's why I made this setup." Here again, not suggesting Tony et. al. fall anywhere near this category, but if you're going to bring the technical explanation, then bring it all, or specifically disclose that the information is proprietary. I really hope I am not coming off like a jerk, there may be reasons that we'd like to incorporate into our own designs, I just haven't seen any hint of them, at least in my own critical viewpoint.

And, in AirRide's defense, one would ask why the fastest cars in the world don't use this technology (F1...)? The FIA banned active suspension systems years ago, before they ever made a big splash. As far as I can tell, however, they didn't rely completely on pnuematic systems. Other venues don't hold this restriction, I have yet to see such a system in use though this does not mean by any means that it is not the case.

Mark

PV = nRT, sort of.

[USAZR1]

Mark,not being a wiseguy or anything but how many people on this site with all the high-zoot ideas can back up their claims of what their suspension can do or Prove it can do what they say? I know you and others like the racetrack but is that the only way? A lot of us don't necessary agree with that so again,where do you go from here without confusing us with all your technical jargon. I'm sincerely interested in some of your answers.
I got flamed awhile back because I thought the new Baer monoblock calipers were going to be good stuff. Seems like I remember one of the guys that flamed me,,later posted and thought they were good,too. New ideas like Air Ride are coming along every day. Let's give some of it a chance before everyone starts hammering away at it. Not too much to ask,,is it?
I'm trying to soak up all this good knowledge you guys are willing to share so cut me just a little slack,,ok? :) :) :)

[TonyL]

After seeing airrides challange on tv, im very interested. As far as the tech questions and theory questions people need to remember that these same systems have been used on lincoln mark eights for years. Those cars handled awsome. Trying to compare air ride to actual springs is an apples to oranges situation. While they both do the same jobs they go about doing it differently. One doesnt need the spring rate info if they have the psi info and know what that info means and how to apply it. (i think thats what tony was getting at) All I know is that my car rode on air springs. I never had a problem and it performed great. My next car will be bagged. I'll track that car, and drive it every day and park it at shows and reap the benifits of the air ride at all three places,- effortlessly and confidently.

[sinned]

Here is my take-for a lot of guys the tech is extremely important and since this board was based around that back in the good old days that is the way it should remain. The fact that we have grown and have many new faces around doesn’t mean we should have to loosen the standards any.



Tony, the Mark VIII handled great compared to what? Not compared to a Mustang, Camaro, or Corvette of the same era. That is exactly what Mark is talking about; “air ride is great”. That is an opinion and gives the reader absolutely no idea how it would apply to his project.



How important is the tech? I run 750 lbs springs at 12.5" free height. I plan to run an additional 200 lbs of pressure but at 14" as the new spindles have an additional 1.5" of pin drop. If I wanted to run air bags how could I possibly determine what bags to run at what pressure based on the tech provided so far. Keep in mind that every aspect of the front suspension geometry including all the RC migration, FRCH, camber gain, bump steer, etc. are all based on exact ride height. So if my ride height cannot change for its intended use and I need 950lbs spring pressure what bags do I need and what height should the brackets be welded in at to provide the height@ said pressure? Tech is important unless all you care about is the “bling” factor, which is OK too, for you.

[CraigMorrison]

Tony- are the ART gauges accurate enough to drop air pressure in a spring by only 1 pound? I'll definitely be stopping by the booth at SEMA. We need to meet anyway & I have more questions for you.

[Travis B]

Tony- are the ART gauges accurate enough to drop air pressure in a spring by only 1 pound? I'll definitely be stopping by the booth at SEMA. We need to meet anyway & I have more questions for you.


I'm sure darren@ridetech will be back on here in a bit but, there Ride Pro E setup has a digital read out guage cluster for all four corners and yes it will show a one pound drop..........

[Mean 69]

A lot of us don't necessary agree with that so again,where do you go from here without confusing us with all your technical jargon. I'm sincerely interested in some of your answers.

No offense taken, at all. And frankly, it is a struggle to convince folks of the design attributes of a particular system with facts, it is an un-even playing field relative to the other suppliers who don't back up their claims, well, with anything but soft opinions. If you have suggestions on a better way to do it, we are all ears, honestly.

One of the issues is that people are all so very different in their approaches to pure thinking. Some folks just think differently than others, it has a lot to do with their inherent personality traits. Folks like myself rely as much as possible on facts, and in the absence of facts that stand up to criticism (and not criticism in a bad way, at all), well, suspicion follows. Quickly.

This thread has gotten pretty long, but the title remains clear: Making Airbags work on a G machine. A G machine, to us, implys exceptional lateral grip capability. Beyond getting a cool number on a skid pad, we take this also to mean real world high speed handling, and I am not sure a better place to prove it than on a track, certainly can't do it on the streets (or at least, we won't). Let me put it in this fashion, a skid pad, which is the best direct measurement of G forces, is a lot like a chassis dyno. Both tell you how good the performance potential is, but neither can tell you how well the actual performance will be.

Anyway, I really have absolutely nothing against air bags, to each his, own, really. And to second Dennis' remark about pulling the tech out of the board, well, I think that is not such a good idea. I guess there is no way to make everyone happy?

Mark

[Norm Peterson]

I think what Dennis is looking for is enough data and tech with which to base an informed but independent opinion. Being able to compare them analytically against the known properties of steel springs or torsion bars is part of that process.

It would at least be useful to know how much roll would occur for some given lateral acceleration. That they are progressive is obvious, but how will that progression affect the understeer/oversteer balance? While I'm admittedly looking at this from a hard cornering point of view, it's absolutely true (for myself, at least) that there are upper limits to what I would consider acceptable in terms of roll and possible change in the handling as that roll develops. Even in the only unmodified daily driver that lives in my driveway.

Maybe I'd find that with the appropriate part numbers that those conditions could be satisfied. I'm certainly open-minded enough to accept that possibility. No offense of any sort intended to anybody in the industry in general or this thread in particular, but until I can run through some numbers myself I'd just be taking as gospel somebody else's opinion that's based on what they thought I meant when I said <insert text that would likely not be in normal industry terminology> . . .

Somewhere in there lies the difference between being sold a given item and buying it based on active choice and understanding. Personal experience here has recorded more instances of less than complete satisfaction with the things that I let somebody sell me than those I made a thoughtful decision over and held my ground. Maybe it's me and I just know what I want better than I can explain why. :dunno:

Norm

[Travis B]

I think everyone will agree with me that there are hardcore pro-tourers like Dennis, mean 69, streetfyr just to name a few! That airbags in fact would not be ideal for them as there cars see more track time then others....I don't think anyone here will say airbags are better than springs for hardcore tracking, I don't think the guys at airride would tell you that either! What airride does provide is an upgrade for stock style suspension that allows a comfortable ride, good performance, ride height adjustability, and of course the parking lot hammered look some refer to as bling factor! lol

I could be wrong but I don't everyone on this site is building purpose built race cars.....most cars I see being built here may hit 2 to 3 track days a year some none they just want a car that rides good, handles good, and looks good when they drive it to cruise night or load up the family to go eat etc. etc.
.
please keep in mind these are only my opinions and to most here i'm sure there worthless!

Off soapbox

[Steve Chryssos]

Yup. For the sake of argument, I'm willing to assume that air springs are highly effective.

I only want to know how to properly select the right airbag for a particular application. The Air Ride Challenge and Lincoln Mark VIII both benefit from experienced techs on hand to select, test and swap right components until the proper combination is achieved. The average enthusiast does not have that luxury.

So the question remains: Given that airbags work, how does one select the right air springs for a multi-purpose application--show, street and performance?

It's a problem that needs to be addressed. The average pro-touring enthusiast is building a multi-purpose vehicle. So he WANTS to know cam specs and injector capacities and gear ratios, etc. In order to effectively penetrate the pro-touring market, air bag manufacturers have to provide more than just "make & model" info.

Does the guy with the Wayne Due clipped, small block, full cage, track day 68 Camaro get the same bag as the average ride height, big block street & show 68 Camaro?

[Steve1968LS2]

What if we took a car that has a known baseline (like Johnny's '76 Camaro) and installed the whole shockwave/air-bar suspension and then re-tested the car?

Would that be beneficial information?

[TonyL]

What if we took a car that has a known baseline (like Johnny's '76 Camaro) and installed the whole shockwave/air-bar suspension and then re-tested the car?

Yes.

But, what steevo (and I) want to know is,,, What happens when you bolt up the "wrong" stuff? Show us more than one system, the effects of either, so we can tell which is more "performance oriented"

Install different shockwaves and bags out back and see if it matters.

But yeah. Thats a tech article you MUST do. The readership is crying out for more info on it.

[Steve1968LS2]

Yes.

But, what steevo (and I) want to know is,,, What happens when you bolt up the "wrong" stuff? Show us more than one system, the effects of either, so we can tell which is more "performance oriented"

Install different shockwaves and bags out back and see if it matters.

But yeah. Thats a tech article you MUST do. The readership is crying out for more info on it.

hmmm.. then again what happens to ANY system if you bolt on the wrong stuff.. I sorta see you point but isn't it better to show the right way of doing it than all the wrong ways it can be done.. lol

I will get with Johnny and talk this over. I would be curious if his car would pick up performance, loose or stay the same. We should also weigh the car before and after, ya think?

[TonyL]

one problem steve. Airridetech doesn't offer (publicly anyway, based on what I see on the website) a second gen camaro airbar setup.

You get what I mean though, answer the question, "how do i, or they, pick which shockwave is best for my application?"

Is there a recordable/provable/ repeatable difference in performance?

Is there a more "hard core" version? Or is it a "one size fits all" situation?

[Norm Peterson]

At this point, it's not readily clear just what constitutes the "wrong" vs "more performance-oriented" stuff, or how either compares to that which is more generally grasped. I think the point is to determine two or more data points with the bags so you at least have a crude trend to work with. Without that, it's a little like being back when we were younger (much so, in some cases) and barely aware that (steel) springs even came in different rates, let alone what that might imply.

Norm

[MuscleRodz]

Now once you have achieved ride height, making small pressure changes as little as 1-2 psi and up to 5psi either direction of your target height will effectively change the spring rate without changing the height of the vehicle. doing so would be like going from say a 200 to a 225 to a 250 to a 275 ect.... I think for the most part I have made mention of all of this before on these threads.... either way there we have it again...

Like mentioned above, looking at a dynamic spring rate chart for a specific airspring can be complex and exhausting because any given spring with display different characteristics and rates for every PSI change made. They are available though and Firestone does have these charts. Your best bet is to phone us, let us know what you have and we can go from there. We can help you select a spring and give you the designed ride height for your application. If you are wanting to truley boggle your mind, you can contact us or Firestone and get spring charts.

Did anybody read these parts of Tony's posts on page 2? Why don't somebody follow up on this as he said the info is available with a phone call or two.

Mike

[Travis B]

one problem steve. Airridetech doesn't offer (publicly anyway, based on what I see on the website) a second gen camaro airbar setup.

You get what I mean though, answer the question, "how do i, or they, pick which shockwave is best for my application?"

Is there a recordable/provable/ repeatable difference in performance?

Is there a more "hard core" version? Or is it a "one size fits all" situation?


That is coming.....from what I understand!

[David Pozzi]

I would like to see a second gen comparison from stock to Aftermarket combo like Hotchkis or Global West, then show us the selection proccess for air bags and the results of compariston tests between all three with street ride quality comparisons too.

I have an open mind about airsprings but there is a huge lack of understanding (at least on my part) about how they are (properly) selected, and what they really do as far as ride rates.
I tend to be skeptical about things like this since I understand coil springs better than air bags.
David

[Steve1968LS2]

one problem steve. Airridetech doesn't offer (publicly anyway, based on what I see on the website) a second gen camaro airbar setup.

You get what I mean though, answer the question, "how do i, or they, pick which shockwave is best for my application?"

Is there a recordable/provable/ repeatable difference in performance?

Is there a more "hard core" version? Or is it a "one size fits all" situation?

Or do they?? :D

The rest of questions are better answered by the air ride tech guy.. I think there are multiple bag choices like there are multiple spring choices. But, that is a guess on my part. I am not really up on air ride suspensions but I have a feeling I will getting schooled soon..

[Steve1968LS2]

I would like to see a second gen comparison from stock to Aftermarket combo like Hotchkis or Global West, then show us the selection proccess for air bags and the results of compariston tests between all three with street ride quality comparisons too.

I have an open mind about airsprings but there is a huge lack of understanding (at least on my part) about how they are (properly) selected, and what they really do as far as ride rates.
I tend to be skeptical about things like this since I understand coil springs better than air bags.
David

Like I said.. the PHR would be perfect since we have baseline (worn stock).. modified leaf and that would allow for a good comparo to an air system.

I'm in the same boat as you knowledge wise but I am open to the possibility of it working well. Keep in mind that even if it is not the best for an all out race car it could still be good for the other 95% of the drivers out there.

[Travis B]

Like I said.. the PHR would be perfect since we have baseline (worn stock).. modified leaf and that would allow for a good comparo to an air system.

I'm in the same boat as you knowledge wise but I am open to the possibility of it working well. Keep in mind that even if it is not the best for an all out race car it could still be good for the other 95% of the drivers out there.


That is what I was getting at in my post......

as far as different bags go I know there are at least 4 different sizes of Shockwaves with 3 to 4 different shock lenghts per style of bag to be able to obtain proper ride height! When we bag something we call usually Darren@ridetech and ask for his opinion we go over what we need and it is at our door in three days or less!

As far as ridetech as a company they are very easy to deal with and very friendly!

[BRIAN]

I can't type as much as you guys.


I guess the info I would need is if I set a car up and the spring is too soft or stiff I have the option of opening a catalog and seeing the options of rates and heights I would need. I do not see that option with the bags. Pumping it with addl air is only going to screw up my height from what I see.


If you bag guys have a away or have different rate bags than I guess my question is answered because I could just change them or the bars to adjust as you would with conventional springs. I just don't want to get stuck with a wallowing ride at a certain height. But as someone above posted; if I have 650lb front springs that sit at a particular height where is the guide to cross reference into a bag? With this info I would have to say it would open quite a few more people to use them besides the cars that sit on the floor at shows.

I am sold on them but just don't want to be stuck without an option if I install them that I have with springs. Lets be honest how many people get their spring rates the 1st time out??

[USAZR1]

Sorry I'm late getting back to this topic. Just got off work.
Thanks for not taking my comments the wrong way. In fact,you have brought up some very good questions for discussion and speaking for myself,I've already learned some things I didn't know before.
A few things I've learned about my Air Ride system is that my Shockwaves have a pressure range "sweetspot". What that means is they work very well in a 20-25lb range of adjustment from 80-105lbs in the front and around 60-80lbs in the rear. Above or below these pressures and the ride and handling deterioration is very evident. A big problem I've been having is with the digital control system. It's very imprecise on my car,even after much troubleshooting. I'm in the process of converting the system to an analog set-up that I hope will eliminate the pressure inaccuracies I'm currently seeing. Should have this done very soon and will post my input & thoughts.

Installing a system like mine is not for the weak at heart,money-wise. My four way independent set-up is probably the single most costly mod I've done to my El Camino. If I can get it to work like I think we can,it will also be one of the best mods I've ever done.

[Steve Chryssos]

hmmm.. then again what happens to ANY system if you bolt on the wrong stuff..

That certainly is true with steel springs as well. I went thru three sets of leaf springs and three sets of coil springs. The coil springs have been particularly challenging because the installed height for my early ARDF clip put the car right in between a 10" spring and a 12" spring. The extended length for a coilover intended for a 10" spring is 14" and my installed height is 13.875" So that wouldn't work. I ended up with a 12" body and a 10" 450lb spring cranked way up for preload. Which put the spring near coil-bind--not good. Then I went auto-crossing and the coil springs that worked fine on the street showed their deficiencies on the course. The right spring for my application is a 10" 650lb with an inch or so of preload.

But, I know that I can open up the Summit catalog or the QA-1 catalog and very clearly research free length, diameter and pounds per inch. Those coil springs are about $30, so I can mix and match without severe penalty. And as shown, I can DESCRIBE my coil springs with actual units of measure.

I have access to Pat at QA-1 and can borrow a set of corner scales from my roundy-round buddy. I don't think the average enthusiast has these resources, so most people must rely on the manufacturer for support.

Camshafts are the perfect example. The average enthusiast does not have unlimited access to a dyno. Crower tests a variety grinds, then publishes the specs and operating parameters in their catalog. There are a dozen choices per cam type to choose from. Application, lift duration, lobe separation--the parameters can be described.

In the same way that I just described my coil spring situation, AirRide should publish bag specs to service the wide variety of pro-touring vehicle and suspension variable. They don't have to do this, but if they are promoting performance, then they should provide the specs. Otherwise, folks will invariably choose the wrong parts and provide negative feedback regarding improper handling and/or ride height.

Maybe we should talk about an actual application?? Here's my front coilover specs:
-Coil-over installed length @ ride height: 13.875" eye to eye
-Spring length installed height: approx. 8.5" (1.5" preload)
-Spring: 10" 650lb/in 2.5" I.D. QA-1
-87 Vette Lower A-arms
-Afco upper A-arms
-Car scaled at 3150lbs with 53.5% over the front wheels
-925lbs over each front wheel

I spent a lot of time and money to get my front suspension right--and I learned a lot in the process. The ride height is sweet. The handling is excellent. I wouldn't mind raising the car on demand for NY's mean streets. And improved ride characteristics would be nice. I could care less about "laying frame".

The problem is: How many rodders can call up and provide that level of information? How many rodders even know their cars honest curb weight? Most people "think" their car is lighter than the actual number.

[darren@ridetech]

On the technical side I am working on getting some dynamic spring rate charts for you guys to look over.

As far as physical proof goes.....we are sending two guys to Cali next week to install an AirBar and Shockwaves with StongArms on Johnny's G-28. Mr. Hunkins already has all the performance data with all of the aftermarket goodies installed. So after installing the air ride they will be going back out to Fontana for more testing.

Streetfytr68,
Let's run with your example. Your wheel rate of 925 with an approximate 1.5:1 motion ratio (you might be able to give me an exact on that) applies 1387#'s to the spring. My SKW1000 Shockwave will pick up approx. 2100#'s to ride height with 100psi in it. The SKW9000 will hold 1200# and the SKW7000 around 800#. So if we use the SKW1000 it will theortically require 70 psi to pick up your front end, which is within the capabilites of our compressor systems. We don't like to go over 120psi simply because it is difficult to get that much air in the spring with only 150psi in the tank. But too low of a pressure makes it difficult to fine tune.

So now that we have decided on which air spring to use we must pick out a shock to meet your established ride height of 13.875". Unfortunately you are right between two of my shocks. One having a compressed, ride height and extended dimensions of 10.66 x 13 x 14.76 and the longer is 11.56 x 14.5 x 16.56. Using either of these shocks will cause either a soft ride or a harsh ride and risk bottoming out the shock or topping it out. In your application I would recommend modifying your mounts to meet my ride height specs. Possibly a different mount on your lower control arm. Are you using the T-bar on the bottom?

[Mean 69]

Er, I think you made a mistake. The wheel rate is not 925 lbs/in, the 925 number is the corner weight. You can figure the wheel rate by accounting for the motion ratio, and the given 625 lb-in coil spring.

I would have guessed the same basic conclusion based upon Clint's observation, effective rate is very dependent upon the air pressure, so in order to get everything dialed in, just as you stated, you need to have allowance for mechanical ride height adjustment (i.e. more mounting points). Unfortunately, at least for track day junkies, if you want a stiffer ride, the ride also increases for a given bag, with one set of mounting points. I suppose the alternative is to replace the bags for the track day, much like many folks change the coil-over springs to a higher rate.

Thanks for the input, I think it will help a lot of folks' understanding (myself included). I'd love to see some actual charts.

Mark

By the way, I did a quickie calculation based upon your guess of 1.5 for the motion ratio (which I think it a good assumption for motion ratio). It looks to me like you didn't square the motion ratio in the wheel rate/corner load example, for Steve's example the wheel rate would be 650/ (1.5^2) = 289 lb/in. Not really necessary though, he gave the spring rate, which is what you'd need to determine which spring, at least if he installed in his car, as it sits (i.e. same mounting points). Check my math, I might have screwed up?

[Steve1968LS2]

As far as physical proof goes.....we are sending two guys to Cali next week to install an AirBar and Shockwaves with StongArms on Johnny's G-28. Mr. Hunkins already has all the performance data with all of the aftermarket goodies installed. So after installing the air ride they will be going back out to Fontana for more testing.


Darn it Darren.. you spoiled the surprise!! lol Had them going there..

BTW.. I'm the other guy at PHR :)

The best part is that we have tons of test data on the Camaro and it should be easy to see how the change affected the car. Johnny also has a good "seat of the pants" feel for the car and will know if it feels "better, same, worse" than the modified leaf deal on the car now.

[F70t/a]

Steve,


How long before all the testing and facts will be on PHR?

[Steve1968LS2]

Steve,


How long before all the testing and facts will be on PHR?

I don't know.. Soonest would be the March Issue since Feb is already laid out and in process.. We usually don't sit on stuff very long till it goes to print but the publishing/printing part takes a while.

December is just coming out so I would say that makes it about 3 months.. seems like a long time but that is about how it works.

[Steve Chryssos]

Ow! Now I have a headache. I guess the three bag part numbers represent different volumes? Thank you for responding. I'm looking forward to seeing the charts. So how do you recommend the right bag if the enthusiast does not provide specifics? It looks like a pro-touring enthusiast who is serious about handling should be prepared to gather up data.

As for my coil-overs, they have eyelets at both ends--no T-Bar. A custom fabbed bracket bolts to the drilled C4 vette lower A-arms. Longer brackets could be fabbed.

As for running multiple mounting points to compensate for pressure induced ride height changes, it could be difficult to engineer multiple mounts without causing bag to frame/upper a-arm interference. It might be easier to design the system with a lower street ride height and psi, then put the car at nominal ride height with higher psi on the track.
So given that same application: Say that 70psi works out to be ideal for the street, how much more pressure would be added for track use? No need to be exact, I'm just wondering if we are talkin' about 2lbs or 20? How much change in ride height would be expected?

[Travis B]

Say that 70psi works out to be ideal for the street, how much more pressure would be added for track use? No need to be exact, I'm just wondering if we are talkin' about 2lbs or 20? How much change in ride height would be expected?


Steve from my experience you can add 5-10lbs in the bag w/o changing ride height! As far as what that does to handling i'm not sure just thought I would throw that in there!

[darren@ridetech]

You won't have to change the springs. By adding a couple extra psi you can increase the spring rate. This will also increase the height, but it will be minimal. Probably looking at adding an extra 5 psi to help stiffen it up a bit. A couple of extra clicks in the shock would help too. We also now have double adjustable shocks so that you can adjust comp. and rebound independently. This isn't sounding too much like a sales bit is it......?


Sorry Steve. I didn't know tht you worked there. You gotta let me in on your conspiracies. I should have known those requests were too good to be true. That was just too easy.

[darren@ridetech]

Mean69,
I am talking about the actual weight being applied to the spring, be it air or steel. I am sure that you know that the coil spring rate is determined by how much weight it takes to compress the spring 1". However air springs are rated by how much weight it will lift to it specified ride height with 100psi in it. So you can't really compare the two that easily.

[Mean 69]

I am talking about the actual weight being applied to the spring, be it air or steel.

Yes, and this why you need to figure the motion ratio's influence on the system. I think you are working backwards, as I see it from your math/explanation, the front of Steve's car would weigh 1387 x 2, = well over 2700 lbs. In addition, because this is what the spring sees, this would consistute ONLY the sprung mass, so the wheels, spindles, brakes etc don't come into play, which would further imply that the front of his car is even heavier than the 2700+ pounds? That is basically the weight of his ENTIRE car, not just the front.

I'll concede that there is probably a whole new lingo for the air bag rating that I am not aware of, but it doesn't change the force equations on the static loads seen by the suspension. Maybe the charts will reveal something that is not obvious from the dialogue so far?

Steve (Rupp): Do you guys have data for Johnny's car with "normal" street tires, i.e. not R compound track day tires? I'd like to see the experiment done on a typical tire, or at least make an obvious disclosure about what the numbers would be not using R compound tires. Believe me, I am all for the sticky rubber, but it highly influences the car's true grip in a positive way. As an example, Art's 55 pulled basically the same g-numbers that G28 did, if I recall, but the shoebox was on normal (albeit nice) street tires, very big difference that isn't obvious from the numbers themselves. My guess is that the 55 would have been right at, or over 1 g with the Nitto's Johnny used on the skid pad.

Great stuff, guys, thanks!
Mark

[Steve1968LS2]

Sorry Steve. I didn't know tht you worked there. You gotta let me in on your conspiracies. I should have known those requests were too good to be true. That was just too easy.

lol.. no problemo.. we are installing the goods as we speak.. if all stays dry we should be dodging cones later in the week.

I will tell the AR guys you said hello..

[Steve1968LS2]

Steve (Rupp): Do you guys have data for Johnny's car with "normal" street tires, i.e. not R compound track day tires? I'd like to see the experiment done on a typical tire, or at least make an obvious disclosure about what the numbers would be not using R compound tires. Believe me, I am all for the sticky rubber, but it highly influences the car's true grip in a positive way. As an example, Art's 55 pulled basically the same g-numbers that G28 did, if I recall, but the shoebox was on normal (albeit nice) street tires, very big difference that isn't obvious from the numbers themselves. My guess is that the 55 would have been right at, or over 1 g with the Nitto's Johnny used on the skid pad.

Great stuff, guys, thanks!
Mark

Yea, the car has been tested with radials and with the R-compound tires. I don't think the car did better in the cones or the skidpad with the NTO1 R's (17" wheel) but it did do much better in the braking. I would have to look it up to be sure. Will probley test on the R's though since that is what the car is currently running.

We also weighed the car and the axles to get a before/after comparo on added or lost weight.

[Travis B]

We also weighed the car and the axles to get a before/after comparo on added or lost weight.

that is good idea I will be interested to see the outcome!

[darren@ridetech]

Mean 69,
I think you misunderstood me. I am saying that if there is 925#'s at each front wheel then with a 1.5:1 motio ratio there will be 1387 at the spring.

[Norm Peterson]

Yes, and this why you need to figure the motion ratio's influence on the system. I think you are working backwards, as I see it from your math/explanation, the front of Steve's car would weigh 1387 x 2, = well over 2700 lbs. In addition, because this is what the spring sees, this would consistute ONLY the sprung mass, so the wheels, spindles, brakes etc don't come into play, which would further imply that the front of his car is even heavier than the 2700+ pounds? That is basically the weight of his ENTIRE car, not just the front.If you're going to use motion ratio and corner weight to determine spring or bag load and then go from there to double-check front end weight you need to compute the downward load at the LCA chassis side pivots. With a 1.5 MR, 925 lb corner weights (apparently this is assumed to be all sprung weight?) are balanced by the 1387's at the springs/bags (pushing the chassis up) and 462's at the pivots (pushing the chassis down). Or -925#, +1387#, and -462# to put these numbers into a common frame of reference, and the net vertical force reaction at the chassis is still 925#. BTW, that also means that the local chassis structure is seeing 1850# trying to vertically separate the spring seat from the LCA pickups.

If 100 lb per side is assumed to be unsprung and hence not contributing to the spring/bag load), the loads on the LCAs for equilibrium would look like -825# sprung corner, +1237# spring/bag,
-412# LCA pivot, and 1650# in local chassis structure effects.

Perhaps somebody will take some motion ratio measurements as part of this exercise. A wheel:spring motion ratio of 1.5 sounds a little on the low side (compared to 1.7-ish for 4th gen F-bodies or nearly 2.0 for the G-body). Might sound a bit picky, but if MR didn't get squared in some of the downstream math, it wouldn't be quite as important.

Norm

[Mean 69]

I think you misunderstood me. I am saying that if there is 925#'s at each front wheel then with a 1.5:1 motio ratio there will be 1387 at the spring

Gotcha. Thanks!
M

[darren@ridetech]

Now I'm getting a headache....
The lower pivot on the C-4 is very close to the ball joint. A lot closer than most suspensions. If we were getting that picky we would also have to account for the angle of the coil over, typically 10-20 deg. But this is all just a rough estimate. Let's not try to take it too far.....I can assure you, I am not that smart....


If you're going to use motion ratio and corner weight to determine spring or bag load and then go from there to double-check front end weight you need to compute the downward load at the LCA chassis side pivots. With a 1.5 MR, 925 lb corner weights (apparently this is assumed to be all sprung weight?) are balanced by the 1387's at the springs/bags (pushing the chassis up) and 462's at the pivots (pushing the chassis down). Or -925#, +1387#, and -462# to put these numbers into a common frame of reference, and the net vertical force reaction at the chassis is still 925#. BTW, that also means that the local chassis structure is seeing 1850# trying to vertically separate the spring seat from the LCA pickups.

If 100 lb per side is assumed to be unsprung and hence not contributing to the spring/bag load), the loads on the LCAs for equilibrium would look like -825# sprung corner, +1237# spring/bag,
-412# LCA pivot, and 1650# in local chassis structure effects.

Perhaps somebody will take some motion ratio measurements as part of this exercise. A wheel:spring motion ratio of 1.5 sounds a little on the low side (compared to 1.7-ish for 4th gen F-bodies or nearly 2.0 for the G-body). Might sound a bit picky, but if MR didn't get squared in some of the downstream math, it wouldn't be quite as important.

Norm

[Norm Peterson]

Now I'm getting a headache....
The lower pivot on the C-4 is very close to the ball joint. A lot closer than most suspensions.I'm not sure we're thinking about the same thing here. I'm talking about the relative positioning of those points along the LCA, as seen in front view. Please excuse the lame ASCII sketch with '.' characters used to get around the HTML spacing conventions (just look at the 'red').



. . . . . . . . . . .Spring/Bag
. . . . . . . . . . . . . |
. . . . . . . . . . . . . |
. . . +--------------------^ . . LCA
. .Pivot . . . . . . . . . . . . LBJ


At this point, other factors like spring/bag angle can be ignored or at least assumed to remain constant over the various swaps.

Norm

[Steve Chryssos]

Eyeballing with a measurinng tape, I have a 13.25" C4 Vette LCA (inner pivot to ball joint) with a 10.5" inner pivot to lower shock mount distance. Coilover is at 18 degrees. :drive2:

[Mean 69]

The lower pivot on the C-4 is very close to the ball joint. A lot closer than most suspensions.

That's the lower shock/spring mount, in general folks talk to pivots as ball joints, or suspension bushings. And yes, you're right, the 'vette pieces have the shock/spring mount futher outboard, which means a lower motion ratio.


Eyeballing with a measurinng tape, I have a 13.25" C4 Vette LCA (inner pivot to ball joint) with a 10.5" inner pivot to lower shock mount distance.

And the motion ratio IS: 1.26. Smaller is better, and this is pretty darned good. Gotta love coil-overs. Motion ratio is WAY higher for the cars Norm describes due to the very large diameter coil springs, there simply is no other way to fit the suckers in the setup without moving them inboard. Resulting in higher numerical motion ratios. Requiring far higher spring rates, for a given desired wheel rate. Resulting in more mass (generally), of which half is unsprung.
M

[darren@ridetech]

Let's keep in mind that to determine which air spring to use all we need is a ball park. Air pressure will take care of the rest. But I love talking tech. so......

Any angle change off of perpendicular to the lower arm will increase the leaverage applied to it. Just like mounting the rear coilovers at an angle. For 18 deg. it is only about 10% tho.

When figuring motion ratio wouldn't you have to measure out to the center of the wheel instead of the ball joint?

[Norm Peterson]

When figuring motion ratio wouldn't you have to measure out to the center of the wheel instead of the ball joint?Yes, but it's not the simple measurement from the LCA chassis side pivots to the wheel center (or contact patch, which might differ from the wheel center slightly with lots of camber) that you're interested in. The loaded balljoint is a hinge and the simplified approach to 'leverage' doesn't work once you go past it to locations that are essentially on the knuckle (the knuckle rotates as well as rises/falls). For converting the motion (or rate) at the loaded balljoint to that at the wheel center, you need the distances to those points from the front view instant center. Just knowing the lateral distances is sufficient. A bit picky is that this ratio is slightly variable over the range of suspension motion (like the spring angle), so a thoughtful analysis should probably look at some extremes of suspension movement in addition to the static position.

Fortunately for rough estimates and the original direction of this discussion, this also represents less than a 10% effect. But unlike the cosine function for spring angle this one can be greater than 1.00. When it comes to finally choosing specific part numbers, 10% here and another 5% there is more than one step in available spring rates, so just being aware of these things should help the decision process. Maybe a bag arrangement has the same solution for the range between say, -15% to +10% (which get squared for rate purposes). I don't know, so I guess this is more food for discussion.

FWIW, I find it a little less confusing when the motion ratios relate from the spring motion outward toward wheel motion, in that you always multiply them together. If anybody is like me, dividing a 1.35 [wheel motion]:[spring seat motion] control arm MR by an 0.94 [spring angle cosine function] and then multiplying that result by a 1.03 [FVIC function] is as confusing to keep track of as it is to read.

Norm

[darren@ridetech]

Does anyone know where I can find a smilie face waving a white flag?

[Travis B]

Does anyone know where I can find a smilie face waving a white flag?


:help!:


:hmm:

how bout either one of these.... lol

don't worry darren you guys lost me along time ago!

[ProStreet R/T]

Boy have I been missing out on the fun in here, so lets see if I can throw another wrench into the mix.

When choosing an air bag are you guys (designers or consumers) taking any measures to counter the non-linear spring rate of an air spring. Personally this is one reason I personally wouldn't use an air spring on a track only car. Tuning the drastic rising rate can be a pain at best in many different areas.

Now that being said I would (and hopefully can) definitely run bags on a street/track car, the ride height adjustment is a huge benefit in for what I want to do. Ideally I will build a slight falling rate linkage into the front suspension (shocks/bags mounted parallel with the frame rails :eek:) and accuated with a pushrod of sorts. (similar to how the modern f-cars are designed) This would allow independant adjustment of ride height (via changing pushrod length/shock mounts) with out changing air spring pressure. Will take some tuning but I will be able to raise the car over dips and such, drop it on the ground for show, and have it setup to handle hopefully on par with a coilover setup. It's all in the idea stage right now, will let you know if it really works when I finally get it all built.

Seems everyone is overthinking some aspects while not putting enough thought into others. Nobody says the shock/spring has to attach to the lower control arm, or either control arm for that matter. With a simple link and a couple heim joints you can do some wonderous things.

[Mean 69]

Does anyone know where I can find a smilie face waving a white flag?

Um no, not allowed, unless you are bowing out and not willing to teach and learn, and that certainly doesn't appear to be the case here. Norm is a terrific example of the level of technical help you can find on the sites, if you ask the right questions, and have the right attitude. Heaven knows, he has helped me/us in the past, he has an amazing capability with the pen (keyboard), and is more willing to clarify specific points than most anyone I have seen. And he's right, without the often accompanied internet bravado/arrogance that is often associated with replies of this nature.

I'll admit, I came into this thread expecting to find fault/flaws/incompatibility, and all other kinds of stuff wrong, 'cause I understand what I know, and I don't know this stuff. While it still seems clear to me that there are potential drawbacks, I am WAY more willing to learn about the systems, and less likely to dismiss as a "show car put it in the weeds "yo!" blingy dealy." Please, continue, and for us techie anal dudes, bring data. We thrive on it.

Cheers!
M

[Norm Peterson]

Boy have I been missing out on the fun in here, so lets see if I can throw another wrench into the mix.

When choosing an air bag are you guys (designers or consumers) taking any measures to counter the non-linear spring rate of an air spring. Personally this is one reason I personally wouldn't use an air spring on a track only car. Tuning the drastic rising rate can be a pain at best in many different areas.

Now that being said I would (and hopefully can) definitely run bags on a street/track car, the ride height adjustment is a huge benefit in for what I want to do. Ideally I will build a slight falling rate linkage into the front suspension (shocks/bags mounted parallel with the frame rails :eek:) and accuated with a pushrod of sorts. (similar to how the modern f-cars are designed) This would allow independant adjustment of ride height (via changing pushrod length/shock mounts) with out changing air spring pressure. Will take some tuning but I will be able to raise the car over dips and such, drop it on the ground for show, and have it setup to handle hopefully on par with a coilover setup. It's all in the idea stage right now, will let you know if it really works when I finally get it all built.

Seems everyone is overthinking some aspects while not putting enough thought into others. Nobody says the shock/spring has to attach to the lower control arm, or either control arm for that matter. With a simple link and a couple heim joints you can do some wonderous things.A penny's worth of philosophy here is that it's better to understand the simplest arrangement as fully as possible first before attempting to grasp any complexities that build upon it. We're getting there, myself included.

Yes, bags are nonlinear (in accordance with PV = nRT), and yes, it's at least theoretically possible to arrange a linkage that compensates for it. But when we get to that point it'll also be worth asking the question of just how much the 'rising' part of rising rate is that we're dealing with. I can guess that it has something to do with bag volume and whatever positions that are involved. With far less confidence, I suspect that the nonlinearity might be less than that available in progressive coils.

Mathematically, a bellcrank arrangement is just another variable motion ratio or two. I doubt that it would be all that difficult to add this to an existing spreadsheet and plot it up/play around with it a bit to get a decent feel for this option. But just the process of writing the equations requires some 3-D visualization and forces considerable thought, so for now it ends up on my "something to do at a later time" list.

Physical installation is another story though, as once you go outside the envelope roughly defined by the control arms you do run the risk of space conflict with other components as well as having to ensure that the structure that the bellcranks and springs/bags attach to are adequate for the loads applied (strength and rigidity). Don't take this as discouragement though, as I think a similar approach actually made it to real production in at least one Rover car model some 35 or 40 years ago. So it's certainly do-able even in a street-driven-only car (if a bit wild and "out there"). Go for it!

If I can remember, I'll snap some pictures of the FSAE car that runs at our autocrosses and ask a few questions of the guys that run it. I do know that they have rear suspension coilovers operated through bellcranks with what looked like stroke sending units attached to the ends. In addition, they have some sort of datalogging capability and had a laptop hooked up to the car last Sunday. But as of right now, I don't know if they're following this for position, velocity, both, or doing something else entirely. Waaay off-topic, but I really would have liked to have had something similar to the FSAE program available when I was going to school.

BTW, is this (shocks/bags mounted parallel with the frame rails :eek: ) what you were hoping for? Sometimes I'm paying attention to all the little things (and most of the time my sense of humor runs a bit on the dry side). :guilty: ;)

Norm

[darren@ridetech]

Not bowing out....my math roots aren't that deep.

The design of the air spring is what determines the progressiveness. Generally speaking there are two different types of air springs, convoluted and sleeve. Convoluted air spring are typically fairly progressive and the sleeves are nearly linear. Obviously all air springs are somewhat progressive. The sleeve bags are linear because they actually have a piston that goes up inside the air spring when compressed. The shape of this piston also has a lot to do with it, some are actually tapered to increase the progressivness.

[Damn True]

What is a typical volume delta between static and compressed?

What is the most common operating pressure?

What sort of damping are you using?

[Damn True]

Nuthin huh?

[darren@ridetech]

Depending on the vehicle the typical operating pressure will be between 80-100 psi. Some more some less.

We are using a 16 position adj., billet aluminum fluid filled shock. We also have double adjustables available.

Let me work on the volume delta question again. What exactly is the volume delta, and how does it affect the air spring???? Don't forget I am just a sales rep. :D

[Beige]

Nuthin huh?
Did you have to dig up every 4 month old thread on the subject? One would have done the job, especially since they all contain pretty much the same information.


What exactly is the volume delta, and how does it affect the air spring????
He wants to know how big of a change in volume the airbag sees going through it's travel. Specifically on a suspension going from ride height to fully compressed.

I'd like to add to this and ask what the minimum height that the bags should compress to under use. I'm sure that you don't want them fully collapsed with the suspension bottomed out and that you'd want some space between the top and bottom parts of the bag.

[Damn True]

Did you have to dig up every 4 month old thread on the subject? One would have done the job, especially since they all contain pretty much the same information.




I'm hoping to maximize the odds of getting a response containing specific technical data to support the "works good" claims.

Not holding my breath though.

[TonyL]

I'm hoping to maximize the odds of getting a response containing specific technical data to support the "works good" claims.

I guess you can use the published findings of PHR on the subject as "data" the before and after speaks volumes as to the viability of the systems at work. As for getting hard data on what exactly is going on inside the air spring as it is compressed? True poses good questions. Im confortable in the knowlege that it works. But some people need more info to make a good choise.

Hey darren, you guys have to have an engineer there who could put down the numbers for us. Doing so would help alot. I've always wondered if the air spring needs to be aired up more for a firmer ride at the track? (Thus raising the car up, and changing the roll center geometry)

[Damn True]

I guess you can use the published findings of PHR on the subject as "data" the before and after speaks volumes as to the viability of the systems at work. As for getting hard data on what exactly is going on inside the air spring as it is compressed? True poses good questions. Im confortable in the knowlege that it works. But some people need more info to make a good choise.

Hey darren, you guys have to have an engineer there who could put down the numbers for us. Doing so would help alot. I've always wondered if the air spring needs to be aired up more for a firmer ride at the track? (Thus raising the car up, and changing the roll center geometry)


The PHR test, and in fact the air-ride track day "data" are hardly solid from a tech standpoint.

In both cases they took a car with a 30+ year old suspension that was designed for ease & cost of manufacture albeit with fresh bushings etc. and replaced it with an updated suspension configuration. The change in suspension configuration is the salient factor. Did it work better than OE. Of course. But then just about anything (including suspension systems we would all agree are hardly "ideal") would.

If they REALLY want to compare apples to apples they would take a car that already has an updated suspension configuration with coil/oil springs/dampers and replace the coil/oil with air.

[TonyL]

Im not positive but im pretty sure that's been done, True. you'd have to find the track day info though. (Paging Darren) I remeber seeing them remove a coil over setup from one car and install the airsprings. I remember seeing it on TV. (vaguely)

I think the results were close to the same, without the harshness of the coilover setup.

[darren@ridetech]

I guess you can use the published findings of PHR on the subject as "data" the before and after speaks volumes as to the viability of the systems at work. As for getting hard data on what exactly is going on inside the air spring as it is compressed? True poses good questions. Im confortable in the knowlege that it works. But some people need more info to make a good choise.

Hey darren, you guys have to have an engineer there who could put down the numbers for us. Doing so would help alot. I've always wondered if the air spring needs to be aired up more for a firmer ride at the track? (Thus raising the car up, and changing the roll center geometry)

Adding a couple psi in air pressure won't change the height of the car very much, but will slightly change the spring rate. The adjustable shocks can help this too.

An F6957 front air spring (for example) has a compressed height of about 2.5". However if you are driving the air spring at the designed 4.5-5" ride height you will never bottom it out, and if it was to bottom out it would not damage the air spring. A double convoluted air spring like this one does not require an exteral bump stop. However some air spring do, such as the tapered sleeves. All Shockwaves have an internal bump stop.

[darren@ridetech]

Yes. At the 04 Street Challenge we took a 96 Camaro SS (which had aftermarket performance springs, shocks, sway bars, strut tower braces, and subframe connectors) and replaced the coils with Shockwaves up front and the CoolRide system in the rear. The testing was done with a non biased professional driver in the car. The coils were ran through the cones on the cool morning track and the air suspension was on the hot afternoon track. I do not have the exact #'s but the air suspension #'s were slightly better.

I can sit here all day and talk about how great my product is and how well it handles, but why would you believe the guy selling the stuff....


Some of this information you guys are requesting is pretty complicated stuff and generally very difficult to apply to how it is going to affect the handling on the car. But I will get it for you. It's just not typical tech info that we have on hand. You guys are a little more technical that our average customer.

[TonyL]

You guys are a little more technical that our average customer.

you can say that again. But proving your product here is worth it. These are the guys you want testing your products.

[Travis B]

Some of this information you guys are requesting is pretty complicated stuff and generally very difficult to apply to how it is going to affect the handling on the car. But I will get it for you. It's just not typical tech info that we have on hand. You guys are a little more technical that our average customer.

Actually it seems more like some people obviously have some kind of problem with the idea of airbags and have no real intent on using the product only asking practically useless questions. I believe between ART and PHR they have provided more than enough info to show that airsprings are a great suspension upgrade.

Just my .02cents

[MarkM66]

If they REALLY want to compare apples to apples they would take a car that already has an updated suspension configuration with coil/oil springs/dampers and replace the coil/oil with air.

What did PHR do with their G28 Camaro?

It wasnt't a stock 30 year old suspension. It had higher then stock spring rates, larger sway bar, all new wearable parts, and upgraded shocks.

What more do you want?

[Damn True]

Actually it seems more like some people obviously have some kind of problem with the idea of airbags and have no real intent on using the product only asking practically useless questions. I believe between ART and PHR they have provided more than enough info to show that airsprings are a great suspension upgrade.

Just my .02cents


You talkin to me?
If so, I'll thank you not to put words into my mouth.

Your assertion that my questions are as you say "practically useless" shows me that your level of understanding of the factors that effect how a pneumatic system functions is about on par with Darren's. Minimal.

If you have any tech on the subject I'd be happy to discuss it with you. Thus far I've seen nothing of the sort.

Here's the bottom line, before I put ANYTHING as critical as a suspension system on a car that I or anyone I care about is going to drive I want to make DAMN sure that the product is first of all safe, and second that it will function in a predictable and repeatable manner. The car I am considering an air system for will be a daily driven '65 Chevelle. This car will belong to my wife-to-be. It will get DRIVEN, not backed off a trailer into a goodguys show. The function of the suspension is critical, and ensuring the safety and security of it's operation is paramount.

Seem's to me that a sales representative for the "leading" company offering said products ought to be able to answer some simple questions regarding the effect of first year physics level principles on the performance of critical functions of their system. I'm not going to take him at his word that "it works good". Call me crazy, I want some tech to back that up.

[Norm Peterson]

Actually it seems more like some people obviously have some kind of problem with the idea of airbags and have no real intent on using the product only asking practically useless questions. I believe between ART and PHR they have provided more than enough info to show that airsprings are a great suspension upgrade.

Just my .02centsI wouldn't call them "useless questions". They're the sorts of questions that would come up in any evaluation of lateral load transfer distribution or pitch response (aka "flat ride"). You see more of these questions raised partly because for some things there is no corresponding data for coils, leaves, or torsion bars. For the functions that are similar, the data for the conventional stuff is more readily available. Bags are "different" enough that you cannot make easy comparisons to springs even if you had the bags that were going in and the conventional springs that came out right there on the bench in front of you.

Knowing a little more of the physics/engineering behind them makes it possible (or at least much, much easier) to make comparisons to that which is already known. I'll give you that the bags might very well be head and shoulders above the conventional stuff, at least in some respects and/or under certain circumstances. But if I don't understand why, I'd just be taking somebody's word for it (and I've spent far too many years as an engineer to be comfortable doing that).

Suspension tuning is more than just throwing parts at the car without giving the situation any thought and hoping it'll work out.

Norm

[Damn True]

What did PHR do with their G28 Camaro?

It wasnt't a stock 30 year old suspension. It had higher then stock spring rates, larger sway bar, all new wearable parts, and upgraded shocks.

What more do you want?


In the standard configuration with the standard geometry. It was an apples to oranges comparison. Yes it performed as good or better. But damn near anything would.

[MarkM66]

In the standard configuration with the standard geometry. It was an apples to oranges comparison. Yes it performed as good or better. But damn near anything would.

So you're just not happy with the test because the rear suspension geomety was changed?

Front wasn't.

[Travis B]

You talkin to me?
If so, I'll thank you not to put words into my mouth.

Your assertion that my questions are as you say "practically useless" shows me that your level of understanding of the factors that effect how a pneumatic system functions is about on par with Darren's. Minimal.

If you have any tech on the subject I'd be happy to discuss it with you. Thus far I've seen nothing of the sort.

Here's the bottom line, before I put ANYTHING as critical as a suspension system on a car that I or anyone I care about is going to drive I want to make DAMN sure that the product is first of all safe, and second that it will function in a predictable and repeatable manner. The car I am considering an air system for will be a daily driven '65 Chevelle. This car will belong to my wife-to-be. It will get DRIVEN, not backed off a trailer into a goodguys show. The function of the suspension is critical, and ensuring the safety and security of it's operation is paramount.

Seem's to me that a sales representative for the "leading" company offering said products ought to be able to answer some simple questions regarding the effect of first year physics level principles on the performance of critical functions of their system. I'm not going to take him at his word that "it works good". Call me crazy, I want some tech to back that up.


NO I wasn't talking to just you! I can understand SOME of the questions you guys are asking and why the info would be needed and I'll admit I'm no engineer nor do I claim to be so maybe I am missing something. I have helped build alot of cars with ariride on them no complaints here...maybe you should take a ride in a car with it on it?????

[TonyL]

It was an apples to oranges comparison.

Standard configuration? it had new hotchkis stuff all over? So it was better than new. and performed well on the track.

I think what im hearing you ask is, will a car with a 3 or 4 link rear, and coil overs, be improved upon by going with bags?

-Is that it?

(im just trying to keep this discussion on track. and make the questions your asking easyer to answer)

For the record, their airbags, the bags themselves are based off the same bags that have been under big rigs for years. They are very durable and safe. Lincoln used the "sleeve" type on the mark eight with much success.

Here's a question for the air ride guys, do the bags have a soloniod on them that keeps the pressure from leaving the bag under load? or does the load get sent back throught the system to another on the other side of the car? what if a line blows? will the bag deflate?

[Travis B]

Suspension tuning is more than just throwing parts at the car without giving the situation any thought and hoping it'll work out.

Norm

I can understand that

I could be wrong here but I would say it would be a fare assumption to sy that 90% of the people using or wanting or that have had airsprings are not taking there car to track day every weekend or trying to set any track records anywhere. Most people want a useable suspension w/adjustability, a nice ride, and better handling than the normal bolt ons.....

you guys have your thoughts I have mine....thats what makes the world go around :jump:

[Travis B]

Here's a question for the air ride guys, do the bags have a soloniod on them that keeps the pressure from leaving the bag under load? or does the load get sent back throught the system to another on the other side of the car? what if a line blows? will the bag deflate?

the ART 4 way ride pro uses a solenoid per bag, it adds and dumps the air for that bag. So the air cannot escape that bag unless you hit the switch. If the line breaks or the bag pops(for some strange reason) the air will come out of the bag causing it to deflate

[TonyL]

so, where is theat solonoid located? on the actual bag or the manifold near the compressor?

[F70t/a]

I can understand that

I could be wrong here but I would say it would be a fare assumption to sy that 90% of the people using or wanting or that have had airsprings are not taking there car to track day every weekend or trying to set any track records anywhere. Most people want a useable suspension w/adjustability, a nice ride, and better handling than the normal bolt ons.....

you guys have your thoughts I have mine....thats what makes the world go around :jump:



I agree :jump: Airride is badass

[Steve1968LS2]

What did PHR do with their G28 Camaro?

It wasnt't a stock 30 year old suspension. It had higher then stock spring rates, larger sway bar, all new wearable parts, and upgraded shocks.

What more do you want?

Basically the car had a big sway bar, Hotchkis rear leafs, Hotchkis front springs, Global West upper control arms and all brand new suspension bushings and such.

To call it a "30 year old" suspension is really inaccurate. The suspension on g/28 was typical of your average "upgraded" suspension.

The general though process before our test was that an air spring suspension was all form and zero function. The test showed that it in fact does not handle bad at all. In fact it handled pretty good while still having a good ride on the street.

Does this mean that it's the best thing out there for ultimate handling? Nope.. It just means that you can run an ART system and not flush performance driving down toilet.

We are looking at doing a test where we take a car with a performance suspension (like a three link) and swap out the coil overs for air springs and test. ART was up for this test and I think this shows a certain confidence in what they do.

We can talk spring rates and air expansion theory all day long but the only thing that really matters is time through the cones and other "real" data.

Air Springs are not for everyone or for every situation, but they have a place in our segment.

[Steve1968LS2]

ISuspension tuning is more than just throwing parts at the car without giving the situation any thought and hoping it'll work out.

Norm

It should be noted that we had zero time for any sort of tuning (scales) and this should have helped even more with the numbers.

That's the problem with testing.. the people that are doubtful will always want it done a way different from how you did it. We tested, took stuff off, put stuff on and tested.. there is no way we could do some of the tests people want, it's just not practical.

[Steve1968LS2]

Seem's to me that a sales representative for the "leading" company offering said products ought to be able to answer some simple questions regarding the effect of first year physics level principles on the performance of critical functions of their system. I'm not going to take him at his word that "it works good". Call me crazy, I want some tech to back that up.

Not to beat the horse, but you want to discuss theoretical physics more than you want to see if the system is safe or capable.

Many people run this system, I yet to hear of it having a catastrophic failure (parts snapping, etc.) So I would assume that it's safe. We put it on a car and that car handled better than 90% of the cars on the road so I would again assume it's capable.

They ran cars equipped with this technology at their track day at Putnam raceway. Pushed them hard all day long and even had professional drivers pound on the cars. Again, the components did not fail and the cars handled in a predictable and safe manner.

You want to argue physics instead of looking are real world results. I have seen zero evidence to show that the performance ART system is not suitable for a street car. Do you have any? (again, insert a smilie face here since this IS a friendly discussion) :)

[Norm Peterson]

. . . but I would say it would be a fare assumption to sy that 90% of the people using or wanting or that have had airsprings are not taking there car to track day every weekend or trying to set any track records anywhere. Most people want a useable suspension w/adjustability, a nice ride, and better handling than the normal bolt ons.....Fair statement? Probably, at least for the majority. But you are far less likely to get any technical questions from them anyway.

Not intended as a disparaging comment in any way, but this is the sort of thinking that drives many OE suspension decisions. Just that the aftermarket bag customer is a little more discriminating than the lowest common denominator new car buyer (has a non-zero pulse and a semblance of solvency).

It's more from the hard-core, or those who anticipate having to deal with knowledgeable hard-core customers, that the questions will come, and I think it's also fair to say that this forum includes enough people from that extreme that such questions should absolutely be expected.

Norm

[Damn True]

Adding a couple psi in air pressure won't change the height of the car very much, but will slightly change the spring rate. The adjustable shocks can help this too.



Really?

Since you have thus far dodged every specific question I've asked I'll use some hypothetical numbers for the math as a means of demonstrating the reason for my question.

Now again, the stuff I am using is not as you say "theroy" this is GAS LAW. These are not open for interpretation, they are incontrovertible fact.

Based on:


F = PxA
and
Boyles law: P1 x V1 = P2 x V2
Lussacs law: P1/T1 = P2/T2
Charles law: V1/T1 = V2/T2

Combined gas law: (P1 x V1) / T1 = (P2 x V2) / T2



So if you have air bag with a dia of 5" operating @ 104.7psia @ 70*f you have a "spring" exerting a force of 2055.78lbs.

Now, if you increase the temp. to say 100* (not unreasonable on a warm day, under a running car) with no other changes that "spring" force jumps to 2171.63lbs.

Since you have two at each end of the car the net increase is 115.8lbs in your effective spring "rate". Now to me, having a spring rate that is dynamic and can easilly change by over 100lb based only on a small change in environmental factors is pretty big deal.


Now, you are giving 5" uncompressed height vs 2.5" compressed. Again using 100psia @ 70*f we are looking at 229.4psia compressed. Which of course means this "spring" is, as we all know, highly progressive. How much? Well @ 229.4psia this spring would exert a force of 4054.26lbs!

How are you controlling that w/o position sensative damping?

This is not even taking into account the effect of Charle's law on Lussac's and Boyle's which makes the math REALLY tough, and would further increase the rate of progression and overall "spring" force.

The point of all of this is that I'm trying to figure out, if you guys have figured out how to control this. If you have, great, show me how. If you have not taken the above into account, the result is that you have a system that cannot possibly be controled at extremis and that would be incabable of using the entirety of it's travel.
Perhaps that is why your systems do not use a bumpstop?

[MarkM66]

to call it a "30 year old" suspension is really accurate. The suspension on g/28 was typical of your average "upgraded" suspension.

I guess IMO, a 30 year old suspension is just that. A bunch of worn parts. :drive1:

[Norm Peterson]

That's the problem with testing.. the people that are doubtful will always want it done a way different from how you did it. We tested, took stuff off, put stuff on and tested.. there is no way we could do some of the tests people want, it's just not practical.Understood. The bank of knowledge concerning anything "new" has to start at, ummm, the beginning. Next time anybody runs a comparison or three (and publishes/posts their findings) we'll have a little more.

Norm

[Damn True]

I agree :jump: Airride is badass


There is some solid tech.
Bravo!

[Steve1968LS2]

I guess IMO, a 30 year old suspension is just that. A bunch of worn parts. :drive1:

:doh: I meant to say INaccurate.. lol.. ok, I'm an idiot.. (freudian slip??)

[USAZR1]

Ok,that sounds fair enough. Do you think that Air Ride designed their parts for racetrack useage? No.
Since they didn't design them for such useage,should they have tested them to the infinite extreme like some think they should?
Even if they had done so, ultra hardcore guys turn their nose up at the technology and wouldn't buy it,anyway. Right? So,why should companies like ART try to appeal to you? You're a tiny part of the market and they are having trouble keeping up with demand for their products as it is.
The reason I asked that is it seems like if you don't want the extreme cutting-edge racetrack technology on your car,it somehow marginalizes you on this site,to some people. Last time I looked,this isn't CC. Not trying to stir the pot but the majority of us on this site are interested in real-world useage,not the racetrack. Air Ride works well for the former,probably not the latter,,yet.

[TonyL]

I found some interesting info on the airsprings here. (http://www.goodyearindustrialproducts.com/airsprings/engineering.html)

Since it's all engineering stuff, perhaps you can make heads or tails of it. (requires adobe acrobat.) Lots of charts and graphs and junk.

[Travis B]

so, where is theat solonoid located? on the actual bag or the manifold near the compressor?


we usually mount them near the compressor and tank to limit the amount of lines running everywhere

[USAZR1]

There is some solid tech.
Bravo!

Sorry we're so unworthy,True. :hail:
Lighten up,ok.

[Travis B]

There is some solid tech.
Bravo!


this coming form the guy who started this thread

https://www.pro-touring.com/forum/showthread.php?t=9510

and here I thought maybe you had actually had a couple cars that could preform

:rolleyes:

[MarkM66]

:doh: I meant to say INaccurate.. lol.. ok, I'm an idiot.. (freudian slip??)

I was wondering if that was just a typo. And to think you write for a living, j/k... :seizure:

[Damn True]

Not to beat the horse, but you want to discuss theoretical physics more than you want to see if the system is safe or capable.


Addressing the laws of physics and how those results effect the performance of the system is paramount in determining if the system is in fact, safe and capable. That's what engineers do.

Id also like to know what steps have been taken to address corrosion protection inside the system.

As you know when compressed air is cooled it drops below it's dewpoint and any humidity beyond saturation is condensed out of suspension. That dirty, oily air makes an awesome electrolyte and if there is any dissimilar metals in the system you are looking at corrosion in short order.

[Damn True]

this coming form the guy who started this thread

https://www.pro-touring.com/forum/showthread.php?t=9510

and here I thought maybe you had actually had a couple cars that could preform

:rolleyes:


What would be your point?

The intent of that thread was to tap into the knowledge base of people who have completed top to bottom projects as a means of planning my work so as not to waste time/money. As explained in my request I have built a number of off-road vehicles and AMA road-race bikes as well.

So the fact that I have not yet completed a PT vehicle means I cannot ask pointed questions about components for a potential build?

Whatever.

[Damn True]

we usually mount them near the compressor and tank to limit the amount of lines running everywhere

Do you normally vent to Atm. inside the trunk or do you run a drain line that dumps somewhere under the car?
Is there a flow control on the outlet side of the valve?

[Travis B]

Do you normally vent to Atm. inside the trunk or do you run a drain line that dumps somewhere under the car?
Is there a flow control on the outlet side of the valve?

we usually use a dryer in line that can be found on pretty much any OEM vehicle w/airride that eliminates the corroision and moisture problems that COULD occur overtime. I work at Ford so we use them off of a lincoln TC. We usually vent the air into the trunk(bascially let it run out of the valve into the trunk) I did do a truck earlier this year that vented trough the bed floor towards the ground.

[Travis B]

What would be your point?

The intent of that thread was to tap into the knowledge base of people who have completed top to bottom projects as a means of planning my work so as not to waste time/money. As explained in my request I have built a number of off-road vehicles and AMA road-race bikes as well.

So the fact that I have not yet completed a PT vehicle means I cannot ask pointed questions about components for a potential build?

Whatever.


just thought it was a little strange that a engineering genious like your self need to ask what steps to take his car apart and rebuild it in!

[Damn True]

Ok,that sounds fair enough. Do you think that Air Ride designed their parts for racetrack useage? No.
Since they didn't design them for such useage,should they have tested them to the infinite extreme like some think they should?
Even if they had done so, ultra hardcore guys turn their nose up at the technology and wouldn't buy it,anyway. Right? So,why should companies like ART try to appeal to you? You're a tiny part of the market and they are having trouble keeping up with demand for their products as it is.
The reason I asked that is it seems like if you don't want the extreme cutting-edge racetrack technology on your car,it somehow marginalizes you on this site,to some people. Last time I looked,this isn't CC. Not trying to stir the pot but the majority of us on this site are interested in real-world useage,not the racetrack. Air Ride works well for the former,probably not the latter,,yet.



Totally understand your point here and agree with much of it. My interest in the air-ride stuff is not for my Camaro. As I said earlier my wife-to-be and I are considering also building a '65 Chevelle (vert...ick) for her. My opinion of air suspension thus far has been that it is a show-car specific item. Usefull for rolling around fairgrounds and loading/unloading from trailers.
I have been shown, partially through this site, that it may have a level of usefulness beyond my stated, admittedly prejudiced original opinion.

Because I have experience in engineering air sprung suspension systems in other applications I have been exposed to the aforementioned limitiations of said systems. I have seen how those limitations have been adressed in other applications and am interested in how ART has, or has not adressed those fixed issues.

Someone remind me why am being made to justify having a question?

[Damn True]

we usually use a dryer in line that can be found on pretty much any OEM vehicle w/airride that eliminates the corroision and moisture problems that COULD occur overtime. I work at Ford so we use them off of a lincoln TC. We usually vent the air into the trunk(bascially let it run out of the valve into the trunk) I did do a truck earlier this year that vented trough the bed floor towards the ground.



Not familiar with OEM air systems. Is that dryer a simple mist separator, deliquescant or dessicant?

[Travis B]

Not familiar with OEM air systems. Is that dryer a simple mist separator, deliquescant or dessicant?

dessicant-im pretty sure ART doesn't even recommend them just something we have done on our most recent cars

[Damn True]

just thought it was a little strange that a engineering genious like your self need to ask what steps to take his car apart and rebuild it in!

Again, just looking to see what others have done. Always cheaper to learn from other peoples mistakes than your own. My grandfather taught me that.

If you like I can walk you through the entire dissasembly, overhaul, engine retrofit, reassembly and test flight process for an HH-60J or HH-65A helicopter.

Never claimed to be a genius (but at least I can spell it:doh: ). Thing is there are some incontrovertible facts that effect how a pneumatic system functions that I am familiar with as a result of working with other air-sprung systems. I'd like to find out how/if ART adressed these issues.

[Damn True]

dessicant-im pretty sure ART doesn't even recommend them just something we have done on our most recent cars


I'm sure then that you recomend an annual replacement of the dryer? The stuff does reach a saturation point at which it no longer functions unless you run it through a recirculation cycle which would be awfully complex for what you are doing.

[Travis B]

Never claimed to be a genius (but at least I can spell it:doh: ). .[/color]

:hammer:


I'll leave the helicopters to you

[Travis B]

I'm sure then that you recomend an annual replacement of the dryer? The stuff does reach a saturation point at which it no longer functions unless you run it through a recirculation cycle which would be awfully complex for what you are doing.

well we don't drive the cars that much or have them for that long really....usually build them and sell them!

[Steve1968LS2]

Addressing the laws of physics and how those results effect the performance of the system is paramount in determining if the system is in fact, safe and capable. That's what engineers do.

Id also like to know what steps have been taken to address corrosion protection inside the system.

As you know when compressed air is cooled it drops below it's dewpoint and any humidity beyond saturation is condensed out of suspension. That dirty, oily air makes an awesome electrolyte and if there is any dissimilar metals in the system you are looking at corrosion in short order.

My point was that you could also observe that the system is indeed "safe and effective" without knowing a lick about physics..

Good question on the shock.. I would imagine there is some sort of anti-corrosion coating. I would think ART would be able to answer this..

[Damn True]

I found some interesting info on the airsprings here. (http://www.goodyearindustrialproducts.com/airsprings/engineering.html)

Since it's all engineering stuff, perhaps you can make heads or tails of it. (requires adobe acrobat.) Lots of charts and graphs and junk.


Yeah, that is usefull stuff. Looks like my math above was right :pat: despite the use of hypothetical figures. One of the things those charts do is illustrate the progresivity of an air spring. What they don't do though is explain how to control it.

I know how it has been done in other applications, wondering how Darren's boys adressed the issue.

[darren@ridetech]

Wouldn't changing the air temperature also change the air pressure? So if you have 104 psi in the air spring at 70* then you would have more like 120psi in the air spring at 100* Bottom line....with a given air pressure you will have a given spring rate and height.

[TonyL]

Just a question to you True, doesnt a conventional coil spring's rate also increase similarly with compression? Or am i missing something?
(break it down for me, cus I admittedly dont know all that much about suspensions at all,honestly.)

I used to own a Lincoln Mark eight. it had an airspring setup on it (factory) and it was your basic strut shock. Also having worked around big rigs that also use airsprings (albiet huge ones) They also used standard shocks. They (the shocks on my car) seemed more than adequate, preidctable and safe.

Im guessing perhaps, that all that ART is offering is a spin off of Ford's system. Which has proven itself for years.

What im getting is that True thinks there is some inherent flaw in the design of the system that will lead to a failure or some unexpected feedback from the car?

[Norm Peterson]

. . . doesnt a conventional coil spring's rate also increase similarly with compression? Or am i missing something?
(break it down for me, cus I admittedly dont know all that much about suspensions at all,honestly.)The quick and dirty answer is that "it can, but doesn't have to". That would be the difference between single-rate (or linear rate) springs and progressive ones. The picky answer is that in the first bit of compression from the free length the end coils of even a single rate spring are progressively bottomming out against the seats, which does stiffen the spring slightly. It stiffens again if you compress it to the point where adjacent coils close up. But over the working range a single rate spring will only gain load as it is compressed. Progressive rate springs are intentionally wound to permit adjacent coils to bottom out against each other in a gradual manner as the spring is compressed. As the number of completely independent ("active") coils is reduced, the rate goes up.


What im getting is that True thinks there is some inherent flaw in the design of the system that will lead to a failure or some unexpected feedback from the car?Helicopter experience might make you exceptionally wary of situations that might arise where there is no backup for a forseeable failure that might involve vehicle control. Call it due diligence.

Norm

[Damn True]

Just a question to you True, doesnt a conventional coil spring's rate also increase similarly with compression? Or am i missing something?
(break it down for me, cus I admittedly dont know all that much about suspensions at all,honestly.)

Yes and no. There are progressive and linear rate coil springs. If the wire in the coil is wound with equal spaces between coils, and if the winding itself is equal in diameter from top to bottom then it will be linear. When you see a spring that has some coils closer together at one end, or if the spring is cone shaped rather than a cylinder, it is progressive.


What im getting is that True thinks there is some inherent flaw in the design of the system that will lead to a failure or some unexpected feedback from the car?

Not really a flaw. But an inherent characteristic of air-sprung suspension. If your compression ratio is such that you have a highly progressive force curve you run into a huge problem in damping the system. It's a limitation of speed sensative damping. The solutions are to employ a very low compression ratio (and accept a very softly sprung ride which you can band-aid with excess damping) or position sensative damping.
You can also design a suspension linkage that features a force curve that is complimentary to the progressive nature of an air spring. But that really only applies in the design of a from scratch system. the fact that we are talking about suspension bits that are to be retrofit into an existing linkage prohibits that.

[Damn True]

Wouldn't changing the air temperature also change the air pressure? So if you have 104 psi in the air spring at 70* then you would have more like 120psi in the air spring at 100* Bottom line....with a given air pressure you will have a given spring rate and height.


Yes, that is Lussac's law and actually, the result is 110.62psia.

The thing is, with a given pressure you don't have a fixed rate or height. It is infinitely dynamic based on ambient temprature relative to the temp at which the bag was filled.
Unless you have a pressure controller that constantly monitors the temp/pressure in the bag and holds it at a constant temp (do you?) your rate and height will be in constant change. As I showed in the math a page or two back, those changes can be significant.

Where that becomes a problem is when you take into account that we are dealing with a progressive spring that changes in rate. The damping of the shock is static. Which means at some point you have a spring that is too stiff to allow full travel, and you lose the ability to effectively damp the spring.

[darren@ridetech]

There is a control panel in the car that allows you to monitor the air pressure in each air spring. For now you will have to manually change the air pressure. We are however working on a leveling system that will have a height sensor on each corner that will automatically do that for you.

Below I have pasted an email from Bret Voelkel (guy that signs my check) along with some results from tests that he has been performing.

[TonyL]

where'd it go?

[Travis B]

I saw it....but now it's gone!

[darren@ridetech]

sorry, the chart got all strung out when I posted it. I will put it in a PDF and attach it. Give me a couple...

[darren@ridetech]

Here we go....

[Damn True]

Ok, F=PxA.

I got that, thanks. But, how do you control a very progressive spring with a speed sensative shock?

[TonyL]

im guessing that since the spring isnt subjected to the complete range of motion, that its progressiveness isnt as big a factor? Am i thinking right? Instead of looking at the extreme ends of the graphs, look in the middle, where the spring is operating?

[darren@ridetech]

Yes, I would say that during normal operation you would see maybe 2" of compression and 1" rebound at the wheel. Would you agree? Depending on the motion ratio this will be cut in half at the Shockwave on most independent suspensions, which are the ones that we use the more progressive SKW1000.

[Tony@AirRideTech]

TonyL....... you are correct :)

[darren@ridetech]

I have been looking for some similar test results on a good progressive coil spring. Anyone know where I can find some? Maybe we will just order one....

[Damn True]

Ive not seen published force curve results on coil springs. That dosen't mean they don't exist though. Thing is, that if you have a 700lb linear spring it's rate will be 700lb until you start getting into coil bind, and if you have selected the correct free length you should'nt be getting coil bind.

[Tony@AirRideTech]

Ive not seen published force curve results on coil springs. That dosen't mean they don't exist though. Thing is, that if you have a 700lb linear spring it's rate will be 700lb until you start getting into coil bind, and if you have selected the correct free length you should'nt be getting coil bind.

I think we may all be surprised what some testing may result in the consistancy of "quality" steel springs. Darren, I think we ought to try to get some in here in house and play with them..... :drive2: