77 TA-2nd Gen Suspension suggestions

[EricU]

I am starting a new build on a 77 Trans Am.

The car is a hard top (no T-tops) and in good condition. I would like to build the car as a track car that sees weekend street duty.

I plan on using a LS1/LS6 style engine backed by a 5-speed Tremic, along with 4 wheel discs. I have been thinking of using 17s for the track due the doubling of tire cost going from 17s to 18s. For the street, I don't care what rim diameter as my street tires last a lot longer.

I am looking for suspension suggestions, front and rear. I have tried to do a search on this site, but "second" and "gen" are words that are ignored by the search engine.

Seems that most of the stuff that I find is for first gen camaros.

Any help would be appreciated.

Thanks, Eric.

[zbugger]

First, welcome to the site. Second, there's actually quite a bit of information here that can help you out. How far are you willing to go with the modifications? A good both worlds setup is the Hotchkis TVS kit, primarily for a street car, and the Global West setup for a track car. Then, there's also Lateral Dynamics three link kit for the rear, and I'm not sure when they're coming out with the front stuff. I'm anxiously awaiting that one.

For wheels, 17's are considered pretty optimal, although 18's aren't too far behind. There's still quite a bit that you can do to 2nd gens.

[formula]

Your heaviest hitters for the rear are Global West with their leaf spring setup, lateral dynamics with their 3-link, and air ride technologies with their triangulated 4 link, off the top of my head. All three companies have different suggestions for the front--global west and air ride both have proprietary solutions, and I believe lateral dynamics reccomends using global west stuff. Hotchkis also has their TVS kit, which is much less agressive if you're looking to do a more mild street setup. The best solution depends on what you want out of it, more than anything.

[Marcus SC&C]

Fact is you don`t see much on modifying the suspension on 2nd Gens because they work pretty well the way they are. Stock WS6 TAs pulled .79G on the skidpad on skinny 65 series tires. There`s always room for improvement though. The first thing I`d do is add subframe connectors and new subframe bushings. Next springs and shocks. GW is good source for your application since many makers ignore leaf springs. You`ll benefit from adj. shocks. I suggest Varishock QS1 16 way single adjustable as the best bang for the buck. We`ve found them more durable than QA1s and to have much more consistant adjustments. The front geometry isn`t bad but it could be more aggressive. The alignment specs can also stand to be updated and you probably won`t be able to achieve as much + caster/- camber as you want with stock parts (especially once it`s lowered with springs). The better tubular arms will help with the alignment. If you want to go further we have a Street Comp package that uses our adj. tubular arms and Precision Series tall upper ball joints to also improve the camber curves and roll center location. Finish it off with a set of factory WS6 sway bars or equivalent. They`re great cars. I`ve had 8 of them including a heavily modified `78 TransAm I used to (illegally) canyon race when I was much younger and still stupid enough to do it and get away with it! Mark SC&C

[EricU]

The first thing I`d do is add subframe connectors and new subframe bushings.

Already were on the list, and I should have said earlier that we will be welding in a complete rollbar and I don't mind hacking on the floor plan for any rear-end suspension mods.

Next springs and shocks. GW is good source for your application since many makers ignore leaf springs.

The GW stuff looks good.

If you want to go further we have a Street Comp package that uses our adj. tubular arms and Precision Series tall upper ball joints to also improve the camber curves and roll center location. Finish it off with a set of factory WS6 sway bars or equivalent.

Your Street Comp package with the adjustable A-arms looks like what I have been searching for. You dont need to relocate the mounting locations?


Also, is there a reason that you don't have a Street-Comp AFX Package? It seems that the ability to add 13" C5 rotors would be a plus, especially with new spindles.

Thanks for all the help already. Looks like a great site!

I still have questions on the rear suspension (as well as the fronts); 4-link vs. 3-link or stay with the leafs?

Thanks, Eric.

[Skip Fix]

Global West Del a lum or other solid bushings in the A arms. And NO solid bushings aren't that harsh on the street.

1 1/4" TA front sway bar. A deisel S-10 front spring around 700lbs/in. Rear TA springs and a 5/8 factory rear bar. Bislteins, konis Tokicos.

Look at some of the circle track suppliers also. tehy stil use seom second gens in Hobby Stock classes, and the front subframes in some of the other classes.

1 negative camber as much postive caster as you can get.

Then some sticky tires. Road race slicks are a real kick!

[Mean 69]

We recently have done a ton of homework on the front suspension for the second gen F body cars (we already have THE solution for the rear suspension), and will be introducing one of the key pieces during the PT dinner at SEMA. It'll be a prototype, and some small changes will be made to it, but the design will be the basis for not only this platform, but many others to follow in the near future (hint, it's a control arm, but with some functional differences relative to what is currently on the market). This piece will be followed by a coil-over conversion kit with new lower control arms, and other supporting pieces (anti-roll bar, steering pieces). All using the stock frame, and each piece can be added on in a logical fashion for folks that are on a budget and can't spring for the full set at once. What's it going to do?

The stock F-Body stuff is a great step up from the first gen F body, which people naturally compare the setup to. Even though it's better, it really isn't that great at all in stock form. The nice thing is that the fundamental pieces are close enough that smart changes really wake things up. Specifically, the spindle is FAR sturdier, taller, and has a really nice scrub radius for an older car. The control arms are pretty long, and the ratio of lengths of upper to lower are pretty good too. It's a front steer car, which in itself is not a big deal relative to the rear steer configuration, but it has pretty decent steering geometry. The frame is pretty solid too (as is the first gen, in contrast to what many folks think).

The main downfalls are the roll center migration issues dynamically, it moves all over the place in bump/roll situations which results in some funky feedback and behavior of the car. Worst though, perhaps, is everyone's favorite: camber gain, especially in turns (which is really where it is important anyway). Take a look at a good head-on shot of a second gen hard in a turn, and look at the orientation of the front wheel, flopped the wrong way (there's a great shot of a second gen in one of the recent Super Chevy's that illustrates this perfectly, can't recall which issue it was though). Also, due to the stamped upper control arm, it is really difficult to get a good performance alignment out of the car due to interference with the frame brackets. These issues can be improved pretty nicely with some not terribly invasive changes. And yes, increased positive caster from a dimensional change is one of the things that can be done easily with a new upper control arm, for instance, but there is a bit more to it than that (currently a trade secret, sorry!).

Other things that should be considered are a PROPER seam welding of the front subframe. The setups will need to be fixtured, locked down with the mounting points plumb and square before hitting it with heat, don't just weld thing thing and expect it to stay straight afterwards. On my own car, the factory welds were generally horrible, and though there was no evidence of any fatigue cracking, etc, it just didn't look too healthy. I'd guess that there will be greatly varying levels of weld quality, I happened to get a pretty bad one. If you are going to do a cage, RUN DOWNBARS TO THE FRAME!!!!! This is for any car, full frame or not, but certainly with a uni-body it is a big help.

For the rear, clearly we are biased, but we feel strongly that the Lateral Dynamics 3-Link setup is by far the cream of the crop. Yes, it does require a bit of cutting of the car, just like a lot of other kits do, or mini-tubbing, etc, so it's not going to be for the bolt on crowd. And yes, you CAN use a rear seat, but it will require some modifications to the stock unit, or a simple one can be made from any decent uphoulstery shop in a snap. The second gen cars have "friendly" rear wheel houses too, so a mini-tub job it not terribly difficult to do with just some simple sheet metal, you don't need to buy a set of tubs for the car, but going more than about 2 1/4" or so inboard will require some more sheet meatal work due to the internal structures of the car. Regardless, it is WAY easier than doing a first gen, with or without formed tubs, and should be near the top of the list of things to modify on the car. We are just finishing up a 3-Link install and mini-tub job in our shop on a customer car.

Second gen F Body cars rock. There are tons of them out there and are still a lot more affordable than some of the more "popular" cars such as the first gens. We are hoping to make many of their owners WAY happier with the performance handling aspects, very soon.

Whatever you decide, best of luck, and enjoy the journey, it's a gas.

Mark

[Lowend]

I'm curious to see what you guys are cooking up... I'm hoping for a true a-arm captured upper spring mount so we can use more conventional coilovers.

I generally agree with pretty much everything you have to say... Expect the camber gain... When I see camber gain on these cars its almost always due to the a-arm bushing being worn out. The actual geometry could certainly be made to produce more camber loss, but I don't know about actual camber gain in the stock geometry.
My car at an auto-x below.



No camber gain here!!

Now get me a bit more positive castor, kill the bumpsteer, get me a conventional captured coilover setup (without having to cut the frame), and I'll follow you into the desert

[Lowend]

I got off on a tangent
Eric
I would say your biggest thing to do for a track car (assuming everything on the car is mechanically sound) is brakes, more specifically front brakes. The factory 11" rotor and 1-piston caliper is fine for the street. But if you plan on doing 30 min lapping sessions, you'll need better hardware. My personal favroite is the Baer "track" system. It comes with a 13" rotor and a 4-piston PBR caliper; basically the same setup you would find on a Corvette ZR1 or Grandsport. It fits great, and works great. Order without the crossdrilled rotors.
Note, you need a 17" wheel to fit this

[Marcus SC&C]

Fun thread. We started working with and modifying the suspensions on these cars about 18 years ago. A sharp eye looking at the photos page of our site will note a 2nd Gen with fully adj. true road race IRS with coilovers,inboard 6 piston Alcons etc. It also had totally revised front suspension geometry (even the parts that look stock aren`t even close) and scratch built steering built from NASCAR and road race components. We did that car 5 years ago. Fact is that car`s like that go way past the point of diminishing returns though.
The geometry change of our Stage 1 package is based on the 1970 factory Chevy high performance manual recomendations for road racing the "new" 2nd Gen Camaro. Interesting that even when brand new GM knew the frontend would perform better with a few mods. They modified the subframe,mounts and upper A arms (like a more complicated Guldstrand mod) to raise the RC,reduce lateral migration (which while poor by modern standards is much less than most contemporary GM cars to begin with) and improve - camber gain. We left the subframe and mounts alone and duplicated the modified geometry with our Precision Series tall ball joints and adj. arms. Of course both would have been illegal for TransAm racing but we don`t have to play by anyone`s rules. It`s simple,inexpensive and very effective.

Someone asked about an AFX spindle package. It`s coming! It`s on the agenda right after SEMA. Expect even better suspension geometry ,weight savings,quicker steering ratio and bumpsteer about as good as it gets. Naturally the brakes start at 13" C5 dual piston PBRs and go UP from there. A nice perc is that the Baer 13" GT system for stock spindles uses smaller than C5 (C4) dual piston (not 4 piston) calipers while the less expensive ($1695 vs. $895) AFX 13" package uses larger C5 calipers. Or swing by your local GM dealer,pick up a full tilt ZO6 6 piston monoblock / 14" setup and bolt it right on. The ground work is done we just have to tweak a few things and do final testing yet. We have a `79 Formula Firebird with a healthy 455 to test it in. It`s a tough job but somebodys gotta do it. :3gears: Mark SC&C

[Mean 69]

Lowend, just to clarify, "camber gain," or rather re-state what I actually meant. What I meant was "negative" camber gain, meaning as the car rolls, the relative negative camber increases, to help better plant the tire in hard cornering. Clearly the "best" geometry is the one that makes the tires the happiest, and depending on not only which type of tire you use (street, R-Compound, slicks), but what brand too. A Toyo is different than a Nitto, which is different than a Goodyear, etc. Today's tires respond very differently than the tires that were available when these cars were new (or heck, even relative to tires of ten years ago or less!).

Increased caster is coming. How much would you like? How about if you could make pretty large changes, on the car? Without affecting the length of the upper control arm side to side, if there is a tweak in the frame, etc?

To your question about the coil-over, it's going to be nearly impossible to create a system that doesn't require cutting the frame, or rather in our case, modifying the stock upper control arm mount. You won't have to cut it off completely, but it will require some surgery. The alternative would be to use a far shorter spring package, but in our critical eyes, limiting suspension travel defeats the benefits of a greatly improved spring and shock potential. You have to pick your battles I guess! Traditional coil springs, with the right shocks also work very well, as it's clear you know already.

That's a great shot of the car, nice to see you enjoy it in that fashion. Sounds like there will be some neat alternatives from a few of us in the near future, which is good news for everyone.

Cheers,
Mark

[Skip Fix]

So do the tubular upper control arms have the arc from the cross shaft to the ball joint area that the factory ones do to clear the frame?

It would be great to dial in camber AND alot of caster. Right now with factory stuff and factory frame you have to split the difference.

[Lowend]

No sweat - I assumed that you meant (-) camber gain... As you can see with my car the outer tire is (-) cambered more than the inside on this car. Front suspension geometry is stock, but there is a lot of cool stuff on that car.
As far as castor goes... My shop once tweaked the front on a C4 vette and pulled 22 deg of + camber out of it. That was too much; but 21 deg may have been fine :D

What I'm really hoping is that someone will come up with a pushrod front suspension setup so we can have horizontaly mounted (easy to access) conventional coilovers. I'm not saying that would be easy or cheap.

[Marcus SC&C]

Skipfix I don`t know what Mark (the other Mark) and his crew have up their sleeves (although I`ll bet it`s pretty clever) but our arms do not have a bend in them. There are several reasons for that. Once the car is lowered and especially combined with our taller ball joints the bend is not only unnecessary but undesirable. The arms are most rigid in a flat plane and of course if the adj. sleeves were bent they couldn`t adjust anymore. The beautiful thing about the adj. arms is that you can achieve just about any alignment you like. We`ve tested as much as +12 caster and -4 camber with them. Naturally I`d suggest much more mild specs especially for a street car but it`s nice to know you`ve got no practical limit to what you can do. The other nice thing is that while adjusting them you`re moving only one suspension pickup point per side. With solid arms and shims you`re moving 2 and often 3 points per side which has a big effect on the overall geometry. The fact that they still use a cross shaft allows you to use shims to offset minor differences in the frame etc. if you like to or keep a set of shims just for autocross etc. so you really have the best of both worlds.
As for - camber gain for our purposes here (ProTouring) we`re just shooting for sound geometry,not "perfect" (there is no such thing anyway). Interestingly the camber gain and in fact much of the geometry output of a 2nd gen with the GM recomended mods or our Stg.1 is remarkably close to a 93-02 Z-28. Differences are measured in 10ths of a degree and fractions of an inch. It`s no wonder a properly modified ProTouring car drives and handles just as well (or even better than!) many modern performance cars.
Lowend,an inboard coilover pushrod setup would be really cool but if you want it I`m affraid you`ll have to build it yourself or get a shop to do it for you. We have a customer with a JBL "Cobra" with inboard coilvers,very slick. We`d be happy to do it in our shop but I don`t think it would be viable as a kit. We have a nice neat bolt in coilover conversion from VariShock http://www.scandc.com/varishocks.htm if you want to take the easy way out. We`ve had great feedback from them. Mark SC&C

[Mean 69]

So do the tubular upper control arms have the arc from the cross shaft to the ball joint area that the factory ones do to clear the frame?

Yeah, the arms for this car will have a curved feature to them, i.e. as viewed from above, in order to clear the frame control arm bracket when you adjust fore-aft, and/or when you stack a bunch of shims in the setup to dial in a BUNCH of camber. One of the really irritating things I deal with on my 69, using aftermarket tubular arms, is that the arms hit the frame bracket when I put about 1.4 degree negative camber in the alignment, that's all I can get, and even that is really close. The front curved tube is the culprit. I could actually stand even more static camber (track setup), but can't adjust it because of the arms. We'll be fixing that issue here pretty soon too.

Funny, we were going to do a pushrod suspension system, as much to "show off" a bit as well as slightly improved function. We still have the design drawn up, but I doubt we'll ever use it, outside of some of our own cars internally. It's actually pretty cool, you can set the system up so as to get a true rising rate wheel rate in bump, or falling, basically anything that you want, by manipulating the geometry of the bellcrank (we already have a bit of experience with bellcranks for the other end of the setup). They are trick, but a heck of a lot more useful on very light cars where unsprung mass is "really" critical, it's important on our cars but the darned things are so much heavier relative to a "real" race car. It's also nice on the open wheel cars because you can get all of the springing media out of the aero flow. Gets a lot more expensive too.

Mark

[TLWiltman]

This IS a really cool thread. This kind of interest is what brings cool stuff to the aftermarket.

This piece will be followed by a coil-over conversion kit with new lower control arms, and other supporting pieces (anti-roll bar, steering pieces). All using the stock frame, and each piece can be added on in a logical fashion for folks that are on a budget and can't spring for the full set at once.

I'm curious to see what you guys are cooking up... I'm hoping for a true a-arm captured upper spring mount so we can use more conventional coilovers.

I think what I'd like to see is a coil-over setup that:
-is height adjustable with minimal fuss (spanner wrench adjustment, perhaps?)
-uses standard "race shock" style mounting (rod ends mounted in double-shear)
-uses off-the-shelf coil-over springs
-the upper mount also gussets/reinforces the UCA mount.

[EricU]

Someone asked about an AFX spindle package. It`s coming! It`s on the agenda right after SEMA. Expect even better suspension geometry ,weight savings,quicker steering ratio and bumpsteer about as good as it gets. Mark SC&C

Mark,

Do you have any customers running your 2nd Gen front suspension in the Nor-Cal area? I run most of the Nor-Cal NASA weekend and mid-week events in my CTS-V (which has NO roll cage or race seat, which is why I am building the TA).

Also do you know when you expect the 2nd Gen AFX spindle package? I plan on starting with the front suspension, engine conversion (LS1/LS6) and five-speed. Then work from there.



And one more question, what are the advantages/disadvantages of a coil over?

I know my questions are on the "rookie" side, but I just got bit by the road race thing about a year ago and I am not looking to reinvent anything that you guys have already figured out!

Thanks for all your help, Eric.

By the way, I was planning on blowing off SEMA this year, but I might have to stop in for one day after this thread!

[wick]

Mark, what front and rear springs would you recommend when using your control arms and ball joints. I want my '73 455 TA to handle better than stock. I have Rancho front and rear bars for it and I am about ready to change the springs.

[barch1968]

I have a 79' in the works and it seems the 3-link is definitely a good set up but what about HTH Truck arm set up? Anyone have any experience or comments?

barch

[MonzaRacer]

Hey guys i just got to ride in a Second Gen with air ride set up(not sure of parts list but WOWOWOWOW. This car rocks, it has a 502, 6 spd 3.73 posi and it flat was a blast out on country roads. well lets see this car can top out at over 150 in very short space in time and scare the crap out of a fella if it didnt have good binders.
I know its all air ride Technologies and this stuff is so awesome with some good stiff A Arms and sway bars wheels/tire and superior binders.
Lets just say WOOHOO!!!!!!!!!!!!!!!
Lee Abel