BBSDesigns

As a Solo1 participant I am constantly looking for the GTA to handle better. In a world where technology is constantly challenging these old cars I find this challenge an oportunity to surprise fellow competitors with newer cars and show what the old TA can do.
So, this is my current setup & specs:
Car weights 3,150lbs.
470hp/500ft lbs.
Khumo Victorracer V700 265/45/16 rears and Hoosiers slicks 245/45/16 fronts.
Complete UMI adjustable rear arms with solid and poly ends.
KONI adjustable rear shocks.
Stock front suspension with Prothane bushings and links.
Stock GTA's sway bars, front and rear.
Stock new front shocks.
Hotchkis 2" lowered springs.
1 degree negative camber.
0 degree caster.
Custom full subframe connectors.
4 point roll bar.
T-top body.
Hawks Notchback.
Car handles great versus stock.
Still finding it a bit with understeer, probabbly because the front Hoosiers are not fresh and are feeling dry.
Could use some advise by fellow road racers 😊

Base91

iTrader: (1)

Is 0 degrees caster correct? There are a "million" suspension threads to read through so start there.

Colt

What's with your caster and camber? you need the aftermarket upper mounts. I think my static camber is about 3 degrees and about 6 for caster. That's as far as my car goes.

Does that roll bar do anything to make the chassis stiffer? As you know, these cars have about the worst chassis ever built, even more so with your t-top car. Sub frame connectors are not enough.

BBSDesigns

There's nothing wrong with my suspension setting, the car handles super great, no body roll, deflection, etc.. but I'm always open to ideas or suggestions.
The reason I started this thread is with the intention to create an "archive" of road racing suspension settings and or tips, including tires that have worked for anyone of you.
My GTA's subframe connectors are not the average over the counter ones offered by catalog. Mine is more like a chassis that has been joined to the car. The car is so stiff I can lift one complete side without chassis deflection with a jack all the way to the rear or to the front.
The roll bar is also welded to this "subframed chassis".

Colt

are you suffering from understeer or not? how did the car handle with freah tires? Most people don't suffer understeer with these cars if you are running the common race spring rates, so it's interesting that your getting this... or your tires are just shot to hell. Caster does nothing for body roll. All it does is help the tires work more efficiently. if you look at your tires, I'm sure you are wearing them into the side wall. There is no way that you are maintaing an even foot print when you are cornering. This could be contributing to the understeer you are seeing. Furthermore, caster aid's in the centering effect of the steering, which is nice when the car is sliding out of a corner and automatically steers to where your car is going. Show me any serious race car that has zero caster.

also, have you ever had your car on coner scales? I think I saw some other posts about your car and you have a lot of work done in removing weight from the front? Do you know what your weight distribution is? I don't think my knowledge of spring rates would apply to your car if your front to rear distribution is way different. for instance, my car with the battery relocated to the spare tire well is 58% to the front stripped out and with a full tank of gas ready to run. Not good at all.

BBSDesigns

My current front Hoosiers are not in their best shape. In fact they were given to me as a contingency plan due to slicing one of my front Toyo R888 while getting the GTA into the trailer. So the old Hoosiers might be the cause for the slight understeer.
The reason my GTA is having zero caster is because the way the custom subframe chassis was made is inhibiting me to adjust caster, that will have to be taken care of later.

But again, my intentions with this post was not to discuss suspension setups for me alone. Please feel free to share your "winning" suspension combo and tire setup so that we all road racers can have an archive in which we can get info and tips to get better handling for our cars.

Here are a couple of shots of my GTA, you can see the extensive front weight reduction and some details of the custom subframe chassis(black square vertical tube shown near the jack, silver color plate near the shock absorber mounting plate)

Good day!

BBSDesigns

BTW, correct edit; Just realized that is not "0" degrees. From what I recall seeing on the screen last Saturday during the alignment session it has about 4 degrees of caster, I

was wrong.

83 Crossfire TA

iTrader: (2)

Typically a good place to start is with the anchient Global West Alignment specs for these cars:
.................Caster...............Camber..................Toe .Total
..................(deg)................(deg)......................(in)
...................L....R................L....R.......................
Street .........+4...+4.5........ -.5...-.5..................... 3/32
Hard Street...+5...+5.5........-1.....-1 ..................... 3/32
Drag Racing...+4...+4 ...........0......0...................... 1/32
Road racing...+6...+6.........-1.75...-1.75................
ShortCourse......................................................1/8out
Long Course......................................................1/16in

and as long as you maintain close to stock geometry they don't change much, the toe in settings change depending on total deflection in the bushings and things (as you get less deflection you end up needing less toe in/more toe out to achieve the same results).

I suspect that your car is significantly lighter than stock, and it isn't so much that your alignment is OK as it is that you have a lot more tire/weight than most of us do so it not being optimum doesn't matter as much.

As far as spring rates and shock/strut dampening, a lot of that depends on the weight that is on them, and without that (and then some experimenting) I doubt anyone could guess what is going to work best on your car.

Colt

Hes not asking how to setup his car.. hes asking what we are running. I'm not sure I want to share my super secret setup yet!

RubberDucky

iTrader: (4)

Still helpful to me. I'm trying to prep my car for road race and needed to know where to start.

BBSDesigns

I totally respect the desision to not to share the record breaker, track master, winning combo some may have, but the idea behind the post is for all of us 3rd gen owners is just to help each other and try to get the best out of our rides. Maybe someone with a very good combo might shed some light and others will follow. Personally any 3rd gen owner is a friend, the enemy ride in Mudstains!!!! Jajaja

paul_huryk

With that staggered tire setup, you are going to get some automatic mechanical understeer, some of which can be tuned away.

My suggestion is to upsize your front tires to the same size as your rears. Or even change the wheels and tires to a wider combo that is still legal (if it is allowed). Can you run a 275-40-17 on the car?

Colt

I would be really disappointed if i were to publish my setup and then tomorrow, a company like detroit speed or hotchkis turns my setup into a kit and starts selling it. I would have done all of the hard work for them without so much as even a hat tip to my development work. But i dont know, i dont ever expect our cars to have the following that 1st and 2nd gen cars have even though Detroit speed recently started selling 3rd gen parts, which are a rip off imho.

BBSDesigns

I can basically use any wheel/tire combo I like, but at a price on penalty points thus probabbly increasing my current category AA to probabbly "U" Unlimited. That dosent really bothers me, I just want to race, but I did install a pair of Toyos 255/50/16 in the front and they rubbed inside the fiberglass fender well eventually braking a piece of it. I'm not sure if the 275's you mention will rub, unless I get them at a smaller diameter.
So Paul, anything you would like to share about your road racing setup?😊

Colt

I'm running 275/40r17's all the way around on my car and dont have any serious rubbing issues. The only time it rubs is near full lock, and that only happens in tight parking spaces. I have about 1/4" of clearance between the strut and the wheel.

83 Crossfire TA

iTrader: (2)

Colt, I'm pretty sure that everyone at this point wants to know what your setup is.

I used to have a pretty competitive setup but it was dirt simple, '83 TA (WS6), cut stock springs, rear isolators on front, hose on rear spring tails, ended up with a ride height just under 26 on the front and just over in the rear, koni yellows and some hoosier G60 15 bias rr tires. A lot of chassis stiffening (all global west), 32mm solid front bar, the rear bar got changed around depending on how short/long the course was (heavier for longer/faster courses or rr), Stock boxed pieces in the back (with fresh rubber bushings, even on the endlinks/sway bar, I found that it wanted to over steer with anything stiffer), del-alum bushings in the front...

My newer 3rd gen (an 87 TA) is going to be very different, but I haven't had much time to play with it. In between I ran an '87 Formula 350 that was an f-stock car all it's life, nothing on that but koni yellows, 36mm front bar and eibach pro springs (don't know if that's legal in f-stock but I bought it that way from a long time racer that bought it new for that, it even came with 2 sets of stock wheels with original tires on one set)

Oh, and sort of overlapping some of that (bought it new when I was still running the '83, sold it 2 years ago well after I got the formula and the '87), a '97 WS6... that one got Konis, eventually cut stock springs but was stock most of the time, rod end/poly end double adjustable rear CA and PHR that always lived with some sort of 275/40-17 race tire on the lightweight WS6 rims. That was replaced by an SHO, which I'm hoping to run a few laps in this summer...

BBSDesigns

My staggered setup is one that I was "forced" to do. I REALLY love the GTA wheels and a few years back I found one pair of GTA look alike wheels(I really dont know where they came from, maybe a Vette) that are 11" wide in a 16" dia barrel. So bought the Kumho's and put the on the rear. The unkown brand wheels came also with 2" thick spacers which are necessary to install the wheels, so ended up extending the rear track unintentionally.
I will fetch a set of ZR1's 17" x 9"/11" for the track that should be better, comments?
I just finished a bolt on F40 style adjustable rear wing, so the ugly one it had before is gone! Anyone doing something in the aero department?
I will post pics later when is painted.

BBSDesigns

BTW, I'm talking about the fugly wing shown in this video. Ahhh... I'm so glad is not there anymore!!!

BBSDesigns

Thought I should share the new wing, F40 style!

Colt

Doesn't your car have a lot of understeer already? The wing isn't going to help with that. These cars are known to have tons of oversteer, if you are getting understeer, most likely you are really close to the stock alignment spec which is designed to induce understeer. I do like the wing though!

BBSDesigns

Well I never said "lots", I said slightly and besides the wing is indeed helping to plant power more effectively to the ground, stabilize the car and definitely noticeable helping with oversteer. It also adds intimidation points which are never too much
Thanks!!!

Colt

Here's a pic from my car. You can see the lengths I went through to get the maximum amount of camber and caster from the car. I have a LS1 MC and booster and also Founders upper mounts. I notched a bit from the mount and had standoff's made to raise the reservoir so everything would clear the mount and strut.

BBSDesigns

Wow! That seems to be A LOT of camber!!!

Colt

Actually, even with the MC partially in the top mount, its not a whole lot. One of the problems with strut type suspensions is that they can be camber limited, these cars are no exception. I cant remember off the top of my head what my camber is, but I think its only about 2°, ill have to check my records to be sure but i'm working out of the country at the moment.

plum92_camaro

With all due respect, I don't believe this. There's no way 600# hotchkis front springs and stock struts are enough to give you "no body roll" unless you aren't driving hard enough. Some stock springs have higher spring rates than Hotchkis. I have konis and have run 850# front and now 1000# front weight jacks and still have SOME body roll.

I run 4 Toyo R888 255/50R16's on my car, no issues. Great tire! The Toyo's and going to 1000# front springs cut 2.2 seconds off my run time. Could probably get a couple more tenths.

I agree with what Paul said. Square tire set up, not staggered. Tune the oversteer out.

rb85TA

I personally would rather a tid bit of understeer vs. ANY oversteer. But, I also plan on driving mine on the street.

Tibo

iTrader: (15)

I also have the LS1 booster and master cylinder with founders mounts. With full adjustment I don't think my mounts touched the cylinder. I did end up having to notch and box in the strut tower brace mounts to allow full movement of the strut mounts. Is your camber positive or negative? Is your subframe setup similar to fueled soul's? Inner and outer connected?

SCCAjunkie

I'd just like to know who is still running "Solo1", since it hasn't existed for 10 years...

kairles

iTrader: (2)

I used the hard street specs and its a night and day difference. Also if you have stock strut mounts thats basically the max for caster and camber. Thanks for posting these.

Colt

The camber is negative. If the car had positive camber, it would be worthless. I have looked into connecting my subframe to the k-member, and i dont think i can do it on my car. I dont recall the exact reason, but it might have been my oil pan kickouts were in the way. I just looked up fueledsoul's car and I dont need sub frame connectors like that. I have a cage.

Also, i think those camber specs from global west are worthless. Just max out the caster and camber and you will still not have enough.

Here is an image of my car.

gojoe

I too would like to know what everyone else has been able to do. I go autocross, currently in CAM T.

Below is a list of what I run...
1991 Z28 Camaro (Stock TPI 350 and Auto)
-Koni Yellows
-Eibach sport springs I think (1" lower advertised) cut rears for more reduction and removed stock isolators for garden hose
-2"hub centric/wheel centric spacers all around
-275/35-18 Continental DW's up front on C6 style 9.5" rim
-295/35-18 (200 treadware) on C6 10.5 rim (tried this on the front on my friends stock height car and worked fine) 315/30-18 on the way for the back (I really think its going to work).
-Big brake upgrade on front (2010 newer Camaro setup)
-UMI control arms out back including panhard (solid) and LCA Relocation brackets
-Del A lum front bushings
-and, True Track limited in stock rear (recent but am liking)

Rolled fenders front, tried the back but your need a big hammer to accomplish.

Not sure how my car would do against others here but I do win CAM T almost every time I compete and there is some bad *** cars that show up every now and then.

Considering my Z-28 runs side by side my 2013 Chevy Malibu 2.0 Turbo (four door family car) in a drag race, I think this car does well.

Placed 5th in PAX times out of 20 competitors last month. What beat me was a couple of C5 Vettes on R-Comps and a 350Z on Pilot Sort Cup 2's and of course some Miata's.

Damn it. Very short courses here and not many big cars.

Tibo

iTrader: (15)

^^
I would ditch the staggered wheel setup. Corvette may use that setup but the corvette is an entirely different animal. What rear brakes do you have? And are you now using an adjustable proportioning valve? It the torque arm still the stock setup? Torque arm as an adjustable tubular piece mounted off the tailshaft could really help on launch and breaking.

racing28x

Springs: Front- 5.5" 1000# Ground Control
Rear- 9" 200# Ground Control
Weight jacks on all four corners
Shocks/Struts: KYB GR2
Tires: Sumitomo HTR Z III in 245/45-17 all the way around
UMI rear control arms and adjustable panhard

Notes: The car is a full interior and stock drivetrain car. It out handles its braking and power capabilities. I've driven it half way across the country on an open-road rally, and on a paved roadcourse. It rides very nice on public roads, and has very neutral handling (front & rear brake away almost equally). Right now the alignment is within the factory specs. My only complaint is that without any subframe connectors or cage my chassis flex is absurd, which leads to very unpredictable things mid-corner if I hit a mild bump at speed.

gojoe

Tibo, have you been down this road? Your insight is uncanny.

Stock rear drums, no proportioning valve and the stock torque arm is in place, been waiting to switch to manual.

But I think your are completely right, swap out the toque arm for an adjustable piece and I think the back will start sticking and start pushing the front.

Maybe then I will understand why you say to ditch the staggered setup.

By the way... just got the 315/30 18 on 10.5 and they fit much better than I thought. No prob's. Makes me want to try 335 (crazy).

actarnoff

iTrader: (1)

I don't think anyone is running enough camber here. These are strut cars with almost no camber gain, and not to mention lowered. I'd find a way to get -3 or more.

BBSDesigns

Here is an update in my GTA.
I am now running Z06's 18x10.5 wrapped with Hoosiers R6's 295/30/18 on all four corners. Still running Hotchkis springs(front & rear). Added an adjustable front splitter. Added carbon fiber T-tops for a weight reduction of 30lbs on the roof. Still using PepBoys default suspension settings.
The verdict:
Now that I am pushing the car with more confidence the body roll is very noticeable. Also the added rear traction is squating the rear. Understeer is under control, much better. Front tires are getting beat on the outside, I need some degrees of camber ASAP. Dont know exactly how much time I cut to my lap times in the previous event(didnt had a transponder, track time event) but now I am as fast or comparable to a SCCA ITR BMW M3 full road racing car that runs locally.

BBSDesigns

BBSDesigns

BBSDesigns

In the pictures you can see the body roll and rear squating. Time for stronger springs.

83RDRACR

When did this thread turn into a hypothetical drag race thread???? Let's get back on track.

rb85TA

83RDRACR... what are you talking about man?
All I see are pic's of autocross & roadrace car's...
The last post before yours, is talking about body roll & the fact that there is a lot of squat in BBSDESIGN'S car in the pictures he posted above that.
How is any of that equivalent to or addressing drag racing?

Tibo

iTrader: (15)

In this picture the front wheels look to sit back an inch or two from normal, is anyone else noticing that? Has the K member been changed or altered? I've heard that the Spohn units move the front wheels back like this but I didn't find any mention of a spohn piece.

rb85TA

Lol, I seen it too... but I'm thinking that it's more of an optical illusion, due to the weight transfer/squat.
JMO

BBSDesigns

Most of the pictures were taken while exiting the corners, that's just acceleration, the weight transfer to rear, a bit of steering input and an optical illusion.

BBSDesigns

What technique/method are you guys using to limit the suspension extension travel??? And how much are you allowing to extend???

rb85TA

That's exactly what I was saying BBSDESIGN'S ����

rb85TA

I don't have any suggestions for your questions, my car is still sitting on the stock suspension and old "red" lowering springs.

rb85TA

I am about to tare it apart and install all of the aftermarket parts that I have for it. Along with a generic 350 sbc & "hotrod" 700r trans... just to get her moving on her own power.