Truck-arm Rear Suspension

[redss86]

Hey guys, I need some info/ opinions on Nascar style Truck-arm rear suspenions. I am planning on building my own setup buy buying the parts from stockcarproducts.com. I plan on buying the monoball arms along w/ their crossmember. All this I plan on incorporating into a tubular frame that will be for an 86 Monte Carlo SS.

My biggest problem is that I am not totally sure on the correct heights to mount this suspension for optimum performance. The car will be used primarily for street use, w/ the occasional track times. I am wanting this to handle extremely well. Along w/ the heights, I am also curious about the panhard heights, angles, etc...

One other thing is that I am thinking about setting this up w/ a full floater 9". What is the general opinion about this type of rearend? Any big advantages or dissadvantages?



Any and all help is greatly appreciated.

[Poopy]

I'm building one from scratch, so far its been fairly straight forward, although I dont have the greatest grasp on all the suspension engineering aspects involved....but with the truck arm theres only two links and a panhard to screw up, so I'm not overly worried about it!

Good luck!

Heres a couple threads that have been discussed already:


https://www.pro-touring.com/forum/sh...ighlight=truck

https://www.pro-touring.com/forum/sh...ighlight=truck

[JMarsa]

No offense, but I doubt anyone is going to answer your post with a recipe for how to set up you car (I hope I'm wrong). There are people here who are very helpful and folks put alot of work into their projects. There are also vendors and site sponsors who frown on people giving away their liveihood. That said. Research. Here and over at cornercarvers.com (be prepared to know your stuff) and anywhere else you can pick up info, buy some software. People here will help you if you try to figure it out yourself (like RC, IC and all those other terms and calculations). Also, my understanding is that even if you live in NASCAR country the truck arm set-up is like magic, and it only stays MAGIC if everyone and their brother doesn't know the trick.

I'm not trying to be a jerk; I bought a truck arm kit. If I had the brains I'd be trying to do what you are, building my own. I just wanted to make sure you got a reply and give you some insight.


Regards,

--JMarsa

[dennis68]

No offense, but I doubt anyone is going to answer your post with a recipe for how to set up you car (I hope I'm wrong). There are people here who are very helpful and folks put alot of work into their projects. There are also vendors and site sponsors who frown on people giving away their liveihood. That said. Research. Here and over at cornercarvers.com (be prepared to know your stuff) and anywhere else you can pick up info, buy some software. People here will help you if you try to figure it out yourself (like RC, IC and all those other terms and calculations). Also, my understanding is that even if you live in NASCAR country the truck arm set-up is like magic, and it only stays MAGIC if everyone and their brother doesn't know the trick.

I'm not trying to be a jerk; I bought a truck arm kit. If I had the brains I'd be trying to do what you are, building my own. I just wanted to make sure you got a reply and give you some insight.


Regards,

--JMarsa

Actually, there is no magic involved in fabbing your own truck-arm system. It is one of the easiest systems to build. Most guys are just too lazy or don't have the tools necessary to scratch build the system.

[gchandler]

I would just like to say that there is more then meets the eye to the truckarm system. I have been involved in the installation of around 50 kits on all types of car, and I can tell you that suttle nuances of the system are responsible for major changes in how the system functions. I will also say that the system as it appears on the early chevy trucks leaves much to be desired.

As for the floater setup just make sure that you get the heavy duty setup that is designed for a car of your weight as I seem to remember the race floaters being offered in various load ratings. Basically I think that they simply use different steel on teh axle tubes.

I am unable to give you any assistance in figuring out how to package and setup a truckarm system, but I can tell you that the prices that Steve at HTH charges for his kits are quite reasonable when you consider the time and effort that has been put into their design and testing.

[wally8]

Jmarti81,

I'm with Denny, there's not much too it. Sounds like you are going to buy your truck arms which will get past one of the common errors. The arms need to be able to twist to work correctly which is why you wouldn't want to fab them out of tubing.

You can see from the HTH webpage where they mount the crossmember so you can get the right idea of length. After that it's just some spring pads, shock mounts and panhard mounts and a bar. Simple stuff that can be sourced from any number of racing suppliers.

You'll be fine with any of the low cost floaters like those from randy's racemart. They'll hold up fine for your app. Be prepared for some extra weight unless you're going to go the extra mile with light parts.

No offense, gchandler, but giving a response of "There's more than meets the eye" without offering any detail is a fairly worthless bit of information. He obviously knows that, which is why he asked the question..... Since you've installed 50 of them, I assume you might have some tech to offer?......


Wally

[Norm Peterson]

Actually, there is no magic involved in fabbing your own truck-arm system. It is one of the easiest systems to build. Most guys are just too lazy or don't have the tools necessary to scratch build the system.

Easy enough to build, but I'd add 'understanding of the kinematics and desired flexibilities/compliances' to that list if you want to tune it to its potential. I think the kinematics is what the original post was inquiring about.

I don't think it's giving much away to say that the PHB should be level with the car at rest (ideally, loaded as it will be driven), that the height to the center of the PHB should remain a bit above that of the virtual intersection of the truck arms under all conditions, and that the PHB should be as long as practical (especially with the monoball arms).

Norm

[wally8]

Norm brings up a good point; it's good to know the relationships of the parts you're putting together.

However, this is a pretty well developed application and as Denny said, if you leave yourself some adjustment you'll be in the ballpark. From there you can tune once it's on the road. Nothing too magic about integrating a bunch of off the shelf parts. Good advice on the PHB mounting.

There's a lot of theory here and that's definitely good but you can build it and tune it around to work. Rear suspensions are much easier to do copycat engineering on than fronts. Break out the welder and go, I say.


Wally

[redss86]

Thank you guys for the info. The more the better. Don't stop.

About the phb, when it is in the center of adjustment, it should be just above the truck arm virtual intersect point and level parallel to the rearend. Or should it be higher or lower in the adjustment range?

Also on the floating rearend. I was going to go w/ the Stockcar Products BN hubs and snouts. I would probably use the steel drive plates. Would these hubs be able to support the load that I would be putting on them. Remember this in under an 86 Monte Carlo SS. Here is a link to the hubs: http://www.stockcarproducts.com/rear12e.htm

thanks again, jmarti81

[dennis68]

Geoff used to work for HTH so out of respect for Steve he's not going to cough any info. I do think he is playing a bit of the part of Steve however making one beleive that is a fairly complex and difficult system to design. It's a pair of torque arms attached to steel crossmember, all of which can purchased at any number of circle track suppliers (which is where I suspect Steve gets his).

I don't want to sound like I am in any way putting down Steve or HTH, he found a market, thats great. He did not however pioneer some great new design that needs that requires hours of design engineering prior to installation.

Leave yourself some room for adjustment at the crossmember for pivot height and at the PHB for adjustment. Start with a PHB height equal to the centerline of the axle and the arms just below frame rail height.

[BRIAN]

I know I am outsider hear but hey HTH had a good idea and packaged it well. I hear a lot of bad opinions about the set up but have never seen a post in regards to the installation. So maybe they are providing a well thought out piece that justifies the price So why pay DSE $375 for springs you could have made for $225? Because you know it is worked out and is bolt in without any hassle.
On the other hand it does look like fairly easy set up and have thought about it myself. To the suspension gurus are there any mtg points to start as reference or just use where the arms fall on front crossmember. I know most suspensions are based on mtg points. I know you would want the arms to wind up as far out on the rear but are you telling me that is it, just bolt them on and go. Panhard bar is to be level as with any set up. If it is that easy I will give it a shot.
I know most don't like set up but you have to admit it is strong and pretty simple to keep novices out of trouble. Also every mag test with a car equipped has been pretty impressive. Just my ideas.

[dennis68]

The arms determine the crossmember mounting location. Mount the arms to the axle and see where the pivots sit, pretty straight forward.

PS, I won't pay DSE 375 for springs, I won't even pay 225. Why not go straight to the spring builder and spec your own?

[yody]

ummm, dennis how many springs have you had speced to your own?...sounds good. How many hours of research will you have to put in trying to get the right specs? is that worth $100 or a little more? and maybe your specs aren't even all that great? Not everyone has suspension guru friends that are willing to share their secrets and tell us how to make a spring and give us the specs. However I could see how somebody would want to as "fun" i might do that down the road, once the car is finished and i have nothing left to do, but when building a complete car, it takes too long to do stuff like that along with every other darn singe thing. One thing i can throw in here(pretty useless huh!) is that the truckarms are notorious for making a lot of noise...at leasts thats what i hear...there was an entire 2 or 3 page post here about the truckarm, do a search.

[68protouring454]

it would cost you at least 400 for a set of custom leafs, anywhere, anywhere, like others have said, someone who knows little about suspension would be way better off to buy a kit, then to fab his own, ****, there are not to many on here that have raced there cars, so does it really matter?
jake

[Poopy]

Here's where I'm at with the homemade truck arm setup I used part of the GM factory crossmember for the basis of my crossmember:

[gchandler]

A while back there was an article run in chevy high performance about an el camino that we equipped with truckarm as well as the HTH front kit.

Between Steve and myself we installed both the front kit and rear kit in one day and drove the truck in testing the following day. The car had a full interior and was a complete running, driving car when it came into the shop and left in the same condition the following day.

This is what you pay for when you build a kit, ease of installation, proven performance and the work that goes into acheving those.

I no longer work for Steve and my statements about the complexity are not intended to sell kits. I am participating in the information exchange that is the heart and sole of this site. I am a satisfied customer and run truckarm on all of my vehicles.

I am not trying to be coy, there are simply rules about disclosure of proprietary information even after you are no longer employed by someone.

My statements are not intended to sell products, I am simply trying to give an idea about what you are jumping into when you set out to design, build, and install a custom suspension system.

Nothing is as easy as it first appears, remember that a suspension system does not exist in a vaccum, it needs to be incorporated into the chassis of the car that it drives.

[dennis68]

ummm, dennis how many springs have you had speced to your own?...sounds good.

A few dozen, takes a couple tries to get the frequency f to r a close match and get a rate you are happy with.

How many hours of research will you have to put in trying to get the right specs?

yeah, it takes a few hours.

and maybe your specs aren't even all that great?

Better than some guys sitting a few thousand miles away that has no ides what else has been done to the car nor it's intended driving conditions

Not everyone has suspension guru friends that are willing to share their secrets and tell us how to make a spring and give us the specs.

How about simply spending a few hours a night for a couple weeks learning suspension design on your own then you won't friends to tell you what to buy

[MrQuick]

you guys get a room already....
i agree, it looks easy, hell throw a few bracket together and weld here weld there...your done right? Wrong.
It takes a lot to engineer a suspension and have it right the first time. It just won't happen. If I didn't have welding or some minute suspension experience I would be hesitant to try to DIY. How much is it gonna cost when your untested suspension desides to unload itself doing 65 mph down the highway. Please leave the suspensions to the experts...or at least do lotsa home work.

[dennis68]

Psssst, MrQuicky. you need to weld the HTH kit in too.

BTW, holy **** the arms are friken awesome. I'll have some more to post latter in the week. Let me get a dry day to play first, the water is killing me, it just gets all out of shape...no fun at 60MPH with tractor pulling doubles riding my ass.

[MrQuick]

cool, let me know how it all works together... I know but they have done the testing and have honest experience. Carefull is all I wish to add.