GM A-body guys and suspension guru's come on in!

[Goatman]

I have decided to start work on the front of my car. I picked it up this afternoon. Its going to be a 70' GTO (right now just a frame and body shell).


So, this is going to be a daily driver with a LS-X based motor and trans. Right now, I have the stock control arms that have been rebuilt with supposedly poly bushings. I never liked them, as they make too much noise. I have a set of polygraphite bushings on my work truck and love them. The rear of the car will be pretty much stock, but I'm going to narrow the frame rails and mini tub the car for bigger tires.

What is the best suspension I can put under the front of my car (handling wise)? I'm talking steering box, control arms, spindles, etc. I'm not interested in open heim joints in a daily driver, nor do I have an unlimited budget.


Let the opinons start rolling!

[sinned]

ATS spindles and steering box. SC&C ball joints and upper arms. Del-a-lum lower bushings. Circle track spring adusters and any of the easily available 9.5" circle track springs (750# would be a good starting point for a street car).

When you do the rear work are you looking at custom suspension or just enhancing what you have?

[Goatman]

Pretty much just aftermarket control arms, springs, and a sway bar.


What is SC&C?

Use the stock lower control arms with Del-alums?

Where would I find the circle track stuff?

[sinned]

www.scandc.com (http://www.scandc.com) , Marcus will check in soon enough

Yeah, stock arms with the Del-a-lum or some other Teflon bushing

www.speedwaymotors.com (http://www.speedwaymotors.com) for spring adjusters and springs. Search that site for "hidden adjusters"

[Goatman]

OK, so my search for adjusters turned up nothing, but I did find the "TRU-COIL™ FRONT RACING SPRINGS - 5" X 9.5". I'll check around some more when I get a few minutes. I have to go to work this morning!



Anyone else have anything to add? Sway bar stuff?

[PT Goat]

Here's the setup in my '65 GTO: AGR variable ratio PS box (I think they call it their "resto" box), Hotchkis 1.25" hollow bar, Hotchkis Biltsteins, Eibach springs, SC&C Pro-Lite upper arms, and reinforced stock lower arms with del-alum bushings. I am using my stock spindles with a Baer serious street setup, so that I can run basically stock 15" rallye wheels for a sleeper look.

[sinned]

hidden spring adjuster (http://www.speedwaymotors.com/p/3389,712_Adjustable-Hidden-Spring-Shim.html)

[shep]

Depending on the size tire you want to run in the rear a mini tub may not be necessary 11.5 wheels fit in the stock wheel wells.

[Goatman]

I was thinking about that. With my drag 70', I basically ran a 29x10.5Wx15 slick by just beating the wheelwell against the frame and trimming the quarter lip back. The tire did rub a bit.


But, I want the car to sit fairly low to the ground and I have to replace the wheel tubs anyway (rotted on the bottoms), so I figured it wouldn't be that much more work.


What's the widest tire you can fit without interferrence (stock)?

[protour_chevelle]

nitrorocket has 315's but his car is not slammed by any stretch. I have 295's that I can slam and clear.

-Matt

[Goatman]

How does your car handle? Do you ever wish you had more tire, or are the mods you've done "enough" for what you do with the car?

[protour_chevelle]

How does your car handle? Do you ever wish you had more tire, or are the mods you've done "enough" for what you do with the car?

I have no clue how it handles lol. Last year I ran the car with the new powertrain, 255/50/16 rubber on all 4, and higher spring rates and lowered 3" front 4" rear. It handle better then stock but nothing breath taking.


More tire is all relative really. Alot of tire will not always help handling/straight line.

BUT with that said. Nitrorocket destroys 315's(but they are a smaller sidewall) with his 1000rwhp. I killed my 255's with that 50 series sidewall from a 1st gear roll over 2nd gear drop into 1st...

How low do you want to go?

-Matt

-Matt

[Goatman]

Not sure. Your car looks low enough, although its hard to tell from that pics in your sig...

[nitrorocket]

Here is a shot of my 315's, they do not rub at all. These are the only current pics I have since I lowered it last month. Keep in mind that a 315 is only 25.5" tall, that is very short. I need a 3.08 gear just to go anywhere!

Matts car must just about be on the bump stops up front!

https://static1.pt-content.com/images/pt/2007/02/100_6859-1.jpg

https://static1.pt-content.com/images/pt/2007/02/100_6852-1.jpg

[Derek69SS]

ATS spindles... SC&C ball joints...The tall balljoints aren't necessary with the tall AFX spindles, just use stock replacement balljoints if you go that route. If the AFX spindles aren't in the budget, you can keep your stock spindles, and run the tall balljoints.

[Marcus SC&C]

True Derek,lots of folks like to use the stock height PC Series ball joints just because they`re stronger and smoother though.

We like to address the geometry problems these cars had (too low roll center,backward camber curves,bigtime bumpsteer etc. etc.) right off the bat to establish a good solid foundation for any other handling parts you may want to add rather that leaving the problems and trying to cover them up with add ons. Any of our StreetComp packages can do that,some more than others. The StreetComp-AFX and Stage 2-Plus are the top choices. The AFX uses American Touring`s excellent tall aluminum spindles and steering arms. They take C5 brakes with no brackets or adapters. They also require 17" or larger wheels. For folks that don`t want to run 17" wheels or maybe you`ve already got big brakes you like on your stock spindles you can do a Stage 2-Plus and get very similar performance and geometry gains with the stock spindles and our tall ball joints. The Plus uses our proprietary SevereDuty X Tall upper ball joint. All our packages include our fully adj. tubular upper arms. Combine this front setup with a set of the correct springs Eibach or the proper circle track springs and adj. are both good choices. Good shocks, Bilsteins for fixed rate or Varishock for adj. rate would be my first choices. Out back a set of Currectrac tubular arms with their enclosed urethane race greasable joints on the frame side will help eliminate binding and wheel hop but because the joints were designed for 4x4 offroad use they shrug off dirt, water etc. and they don`t squeak. :) A Lee 12.7 600 series steering box would be my top choice but any faster ratio box will be an improvement over what you have. It`s a great time to own an A body you can do anything from mild to wild these days with no downsides. Mark SC&C

[USAZR1]

I think trying to run a 11.5" wide wheel under the car would be really,really pushing it. Even a 11" is very snug.

[72 GOAT]

Hey Marcus what is this spring adjuster you guys are talking about and what do you think about the Hotchkis TVS kits?

[Goatman]

Nitro, what do you have for a suspension?


Thanks Marcus. How do your arms perform in the elements? I'm trying to stay away from exposed heim joints due to their potential for premature failure in a street environment.

[Blown353]

Hey Marcus what is this spring adjuster you guys are talking about and what do you think about the Hotchkis TVS kits?

Spring adjuster, used in conjunction with 9.5" springs:

http://www.speedwaymotors.com/p/3389,154_Adjustable-Hidden-Spring-Shim.html

Hotchkis TVS kit: Poor geometry. While it does one thing good (changes the FVSA for a better camber curve) it's built upon the B-body spindles which slow the steering ratio & increases bumpsteer on the A-body platform.

For a true bolt on kit you aren't going to do any better than Mark's Tall BJ/Stock Spindle package or the ATS AFX spindle package.

If you want to custom fab everything then the sky is the limit, including longer a-arms and more backspacing on the wheels to cut down on scrub radius.

The stock rear sway bar mounting method on these cars is far from optimal, I believe Mark is working on a solution for that too that adopts a sway bar setup similar to a 3rd gen F-body (sway bar mounted to the axle via u-clamps and has endlinks going up to the frame.) That's the RIGHT way to do it.

[72 GOAT]

The TVS system I am referring to does not include the spindles or the Upper and lower front control arms, it consist of sport springs (front and rear), rear upper and lower control arms (the uppers are double adjustable), front and rear hollow extreme sway bars, tie rod sleeves and trailing arm braces. As far as the spring adjuster what does it do, what is its purpose? Thanks Dave.

[Tony@AirRideTech]

With our StreetChallenge kit on this Chevelle we pulled 1.12G ( you can actually view all of the Race Pack G2X data on our site http://www.ridetech.com/streetchallenge/trackdata.asp) at Putnam Park road course...and.... the street manors are so good that we drove it back to the shop without needing a back brace. Proof is in the pudding :poke: https://www.pro-touring.com/forum/attachment.php?attachmentid=15657&stc=1&d=1171495528

[Goatman]

Tony, I'm interested in hearing more....

[Blown353]

Tony, what tires were used to achieve the 1.12G number?

[shep]

The spring adjusters are needed because the circle track springs are so short. The adjusters go on top of the spring and you can set the ride height with them.

[Tony@AirRideTech]

Tony, I'm interested in hearing more....

That car was set up with our StreetChallenge package which actually came to fruition because I was being bombarded with " Well sell me exactly what you had on that car".
The Front of the Street Challenge kit uses tubular upper and lower control arms to replace the factory arms. We use double adjustable (meaning you can adjust the dampening rate of both bound and rebound of the shock ) Shockwaves. Inconjunction with that stuff we are also using our Musclebar sway bar.
The rear system comes with new tubular upper and lower control arms to replace the OE stuff.... then we use our F9100 billet endplated tapered sleeve airspring to replace the coil spring and of coarse.... a double adjustable Shock for tuning and a rear sway bar.
The compressor system in that car is the ARC4100E2. That is all 1/4" lines and fittings, our Ride Pro Valves, new E2 Electronics and control system, 5 gallon tank and two of the Thomas "Mil Speced" 327 compressors.... and of coarse remote controls to screw with the drunks in front of Denny's at 2:00 AM. The only upgrade to the compressor system would be to add the LevelPro electronics which I highly recommend if you are planning on "driving" this thing... it takes the thought out of everyday driving and always inflates up to its proper ride height on start up regardless of load, passengers, or how many beers are in the cooler in the trunk. With this system you still have full manual control that will automatically override the ride height feature just as soon as you push one of the inflate / deflate buttons on the control panel.
The only item on that car that we had on there besides our kit were a set of the FatMan's taller drop spindles. The A bodies handle awesome in that configuration. I got in that Chevelle at the autocross in Nashville and within the 20 minutes that I was able to play around, I already had it into the mid 14's. This is also the same identical set up on Bret's GSX which if I remember right was the fastest car on street tires down at the Pigeon Forge event last year. Now....If actually read through all of this jargon and your brain is still intact and functioning.... you need to get a beer and take a noodle break :rolleyes:

[Tony@AirRideTech]

Tony, what tires were used to achieve the 1.12G number?

The tires were Michlin Circuit R (S7-compound) 325/18 rear and 285/18 front....Just kidding...:rotfl: no telling what we would have done with something like those on there. The tires we were running were BF Goodgrich Comp TA KDW... and I think we had a 245 front and a 275 in rear. Keep in mind, those are street tires not R compound tires and they really were not that wide of tire...... :)

[Derek69SS]

The only item on that car that we had on there besides our kit were a set of the FatMan's taller drop spindles.What did you do about the FatMan spindles bumpsteer issues?

Was that 1.12 G peak or sustained?

[Marcus SC&C]

Goatman, they hold up really well in the elements. The only thing the plating on the arms doesn`t seem to like is road salt. One of our test cars has 4 Pennsylvania winters on it where the arms were heavily crusted with road with salt for months at a time. The coating just takes on a dull look. Powder coating is an option if you plan to use your GTO as a snow plow. :eek: BTW this car has the "race arms" on it with the greasable bushings and over 50,000 miles on them with no measurable wear yet. We haven`t had much luck with heims in real street applications either. We have a big drawer of them in different brands and sizes that wore loose enough that they rattled or buzzed on street cars and had to be replaced. We save them for offroad applications. My general rule of thumb is that if the car has open headers I`m fine with using heims. Low stress applications like swaybar end links are the only exceptions I like to make.
Tony I`ve been pretty impressed by the performance AirRide is getting out of their cars on the track. It goes to show once again that with improved suspension geometry (the FatMan tall drop spindles aren`t the ideal choice but they`re much better than stock,except for the added bumpsteer),higher spring rates (air springs are still springs),good adj. shocks (Varishocks make up the shock part of Shockwaves) etc. etc. these old muscle cars can go toe to toe with the best new performance cars.
If I remember right from your adv. seminar the bags have somewhat of a sweet spot in a particular installed height range. Does getting 2" drop from the FM spindles make it easier to hit the target spring rate/air pressure for track use on those cars,with the Shockwaves? Mark SC&C

[Goatman]

Thanks Mark. One last thing, do you agree with the recomendation of circle track springs along with your setup, or is there a better way that will get me where I want to be?


I had TRZ Chrome-moly control arms on my drag car with HAL coil over fronts on my drag GTO.

[Tony@AirRideTech]

What did you do about the FatMan spindles bumpsteer issues? Delt with it the best we could :confused:, in all actuality, after running the piss out of the cars and putting a lot of miles on it... I would have never had believed the bump steer run out if I had not seen it with myself

Was that 1.12 G peak or sustained?... I guess you could call that average sustained peak.... ha ha ha ha ha ha .... you can actually track all of the downloaded info per lap in that car and track the G pull for the whole coarse.... its actually pretty cool stuff. But if what you were getting at "is that what it spiked to shortly before it ran off the track" ... nope:bananna2:

[Karch]

EMC and Jon Kaase.

[Twentyover]

Attempting to steer this back on topic, or close to that, asking thos of you with some experience, should I be looking at the Std`or Extended spring shim? Using a 600 lb spring in a G body, this is also probably applicable to the A bodies under discussion

[Derek69SS]

On an A-body, it works best to use the tall style shim with a 9.5" x 5" spring... not sure if there's any reason to do it differently on a G-body???

[derekf]

I've removed the bickering. Don't start it back up.

[Twentyover]

I've removed the bickering. Don't start it back up.

gee golly Dad- they started it

[Twentyover]

On an A-body, it works best to use the tall style shim with a 9.5" x 5" spring... not sure if there's any reason to do it differently on a G-body???


Probably not- Are they used in the front and rear both? I saw on Thrasher Steilow was using them in the front to adjust ride height, not just corner weighting.

Probably the worst case scenario woul be needing to cut them back out; or cutting down a lighter spring to get the rate and the height adjustment

[Derek69SS]

On a Chevelle, you can use the short style shims on the rear with a 11" x 5.5" single-pigtail spring... although on my car the ride height was perfect with the 11" springs and no shim installed.

[Marcus SC&C]

Just FYI G bodys use 5 1/2" OD springs. 5" springs don`t fit properly. Mark SC&C

[72 GOAT]

Hey Marcus would you happen to know if I would need to use any shims on my A Body with the Hotchkis TVS system?

[Twentyover]

Well, the spring shims are good for 5 or 5 1/2" OD coils, so I guess I'll investigate them