View Full Version : air suspension article in Hotrod magazine
I can't stand it...I have to make sure everyone picks up the Jan07 Hotrod magazine. Marlan Davis has run a 10 page tech article on air suspension.
I think that Hotrod has GREATLY expanded their definition of "expert" when used in the same paragraph as my name [LOL].
I am obviously biased, but there is a lot of good info there. I was glad to see that they concentrated on the true performance benefits rather than the asthetic aspects of the systems. Also, let me publicly thank Scott Killeen for dropping what he was doing to come down and shoot these pictures for this article.
I also think it is important to note that if it weren't for the interest of the readers [caused in no small part by previous PHR, Super Chevy, and Chevy High articles, as well as direct requests from readers] the Hotrod article would have never happened. Whether anyone beleives it or not...at this level the magazines really don't care who spends what money...they print what will sell magazines. [ask me how I know that]
Interest starts at ground level...YOU guys expressed interest, so the magazines figure that there are many more of YOU guys who would buy their magazine if they addressed these issues. so...THANK YOU!
BretB
11-18-2006, 04:56 PM
Good article. My twin brother and I are building a '69 GTO with your Air Ride suspension front and rear. You can see some buildup pics in the Project Updates section under Project Executioner.
Bill Howell
11-18-2006, 05:00 PM
Way to go Bret. I am waiting for my copy to show up in the mailbox. I went to Books-a-Million today trying to find a copy of Hot Rod and Super Chevy, but neither are out there yet either. I cannot wait to see the article. Did they do an install in the article?
MonzaRacer
11-18-2006, 05:59 PM
High five's to ya man. time will tell but ART and air ride does it right. Over 2 years and some fixing of my measurig mistakes and the truck still rides tight. I just gotta get the couple of pesky leaks fixed and get my "new" compressor (a York/Tecumseh) and brackets touched up looking right.
My truck may be no buck but its been on the road for 4 yrs baring one day with no pinion nut and over 2 of it on ART.
Simple or all the bells and whistles it does the job and I can only hope my 77 Monza sets up as easy too.
Ernest L. Abel
TheMonkey
11-19-2006, 09:30 AM
Bret-
i enjoyed the article as well.
air ride is a serious consideration of mine for a '61 bonneville. the rear should be easy as it is coil spring. the entire front end might be swapped so i'm not sure on that yet.
a couple questions:
if using the LevelPro system, are the algorithms able to be modified and to what extent (for instance, the 20% pressure difference cap)? can the LevelPro system accept one PWM signal from an ECU to accept a ride-height input, or do active systems need to bypass the LevelPro system entirely?
what i'm working on is this: i'd like to design a combo system (pressure & height) that will adjust ride height automatically based on speed (lower at highway speed), and when electronic tranny is put into P to lower the car as well. the active system would be driven by a megasquirt system.
has anyone done something along these lines? any suggestions?
thanks, and great article. congrats.
Scott.
if using the LevelPro system, are the algorithms able to be modified and to what extent (for instance, the 20% pressure difference cap)? can the LevelPro system accept one PWM signal from an ECU to accept a ride-height input, or do active systems need to bypass the LevelPro system entirely?
what i'm working on is this: i'd like to design a combo system (pressure & height) that will adjust ride height automatically based on speed (lower at highway speed), and when electronic tranny is put into P to lower the car as well. the active system would be driven by a megasquirt system.
has anyone done something along these lines? any suggestions?
thanks, and great article. congrats.
Your request is a step above the average questions, I must say...
Since you need VERY specific and technical information I would like you to talk to our electronics guy, Britt Marolf at our shop. [812.482.2932] He is better equipped than I am to accomodate your questions. [In English, that means he is smarter]
In general, I think your project can be accommodated, if not with the current version, then possibly with upcoming versions still in development. I would suggest that you play with a live LevelPro system for a bit to determine what you want in the real world. I had a whole different idea of what really works after living with some of my initial choices for awhile :).
jaybee
11-22-2006, 08:16 AM
That's very Porsche Cayenne! What a cool idea. One question about varying ride height with air pressure, however. If you raise the ride height by increasing air pressure, you're actually doing so by increasing the spring rate. Obviously the reverse is true when lowering the car. By doing so, aren't you increasing the spring rate when you could best take advantage of full suspension travel by reducing the spring rate, and softening the spring when you would really prefer to have a firmer suspension? Maybe my mental picture is wrong, but in my head a car that's lowered with air pressure should behave very similarly to a car with old, saggy springs.
Nine Ball
11-22-2006, 10:53 AM
Congrats on the coverage Bret! I enjoy reading all techical articles, even more now that I write/shoot for GM High Tech too.
Tony
That was a great article. Good reading for sure.
Kurt
Larry Callahan
11-23-2006, 08:48 AM
Congrats Bret! I just got my copy last night. Great article for air suspensions. I can't wait to get me car running and pitch my stock suspension in the dumpster. lol
J2speedandcustom
11-23-2006, 02:22 PM
Great article Bret! 2 of the current cars we are building will be air ride setup. I can't wait to run our 69 Camaro with coilovers up against our customers 69 Camaro with air ride...:twothumbs
67SSDan
11-23-2006, 02:38 PM
Great article Bret! 2 of the current cars we are building will be air ride setup. I can't wait to run our 69 Camaro with coilovers up against our customers 69 Camaro with air ride...:twothumbs
Ooo man, you should definitely bring those cars down to next years 'run through the hills'... I'd like to see that match up myself. Of course.. I realize you're willing to drive all the way from NE just for me.
Dan
That's very Porsche Cayenne! What a cool idea. One question about varying ride height with air pressure, however. If you raise the ride height by increasing air pressure, you're actually doing so by increasing the spring rate. Obviously the reverse is true when lowering the car. By doing so, aren't you increasing the spring rate when you could best take advantage of full suspension travel by reducing the spring rate, and softening the spring when you would really prefer to have a firmer suspension? Maybe my mental picture is wrong, but in my head a car that's lowered with air pressure should behave very similarly to a car with old, saggy springs.
It depends very much on the configuration of the airspring. If you are using a straight sleeve airspring with a straight or reverse tapered piston [smaller at the bottom] then lowering the air pressure would also lower the springrate in about the same proportion. If you are using a double convoluted airspring or a sleeve type airspring with a positive tapered piston [piston is larger at the bottom] then lowering the air pressure can actually increase the spring rate. I know this concept is a little hard to visualize...it took me awhile to get next to it. I amy try to get one of the Firestone engineers to help with some graphic aids to explain.
As with any fine tuning, it is a matter of juggling compromises. In most cases we use a double convoluted airspring in the front and a straight sleeve airspring in the rear to meet the load capacity and suspension travel requirements. The effect of this is that lowering the overall air pressure [slightly] will pick up the spring rate in the front [many times inducing more negative camber as well] and drop it slightly in the back [usually letting the car roll over slightly and bite better].
Keep in mind 2 things here: 1. This is a broad generalization that has not addressed any issues with shock valving, tire pressure or swaybars. 2. We are talking SMALL air pressure adjustments here...no more than 10% up or down. [think adjusting air pressure in your slicks] I tune more by feel and by timeslips than by relying on the gauge. Then I use the air pressure gauge to repeat the performance.
Every car, every track and every driver reacts a bit different..that is why the air suspension is such a valuable tuning tool.
I like these questions...this stuff will end up in our new catalog and on the website...THANKS!
jaybee
11-24-2006, 09:34 AM
Thanks for the explanation. Visual aids would probably help. I'm having a little trouble seeing how it works with the double convoluted spring but believe I understand in the case of the sleeve type with positive tapered piston. I was thinking of the air spring as just like an air cylinder, but as the sleeve comes in increasing contact with the piston it increases the area of the piston, therefore increasing the spring rate even though the air pressure is less. I understand that the airsprings have a design range for air pressures and operating range and that changes in air pressure won't correct for mounting the bag at the wrong height. Of course no spring will correct for improper shock valving or any other shortcoming in suspension design or tuning. Expecting the airspring to do that would be unreasonable.
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