GTA1990

iTrader: (1)

Starting to get a bit older now and appreciate ride quality. I've got a WS6 1990 TransAm with the usual TGO thumbs up suspension mods (koni's, cut moogs, adjustable tubular rear bits, bearing strut mounts etc.) and it does handle well- neutral on some airfield track days I've been on. But after spending more time in todays germany coupe's (330ci, 320CLK etc.) they seem to take the turns just as fast (I'm flattering my T/A!) but are much easier on the daily drive bumps.

My T/A also has SFCs. In very layman/ crude terms, I understand the 3rdgens had some pretty high spring rates to partly overcome the flexible chassis. With decent SFCs installed, I wonder if putting in non-ws6 T/A springs, or even possibly firebird V8 springs (still with the thicker WS6 sway bars and keeping the aforementioned suspension upgrades) would net similar to stock WS6 cornering capabilities but with a slightly more compliant ride.

Appreciate hot-rodding is all trial and error with track/ road time but was curious if anyone had tried something similar or had any thoughts about the theory?

Jeffs82TA

iTrader: (1)

That is what they did on the FE-7-FX-3 and so on vettes, lowered spring rated but went with larger sway bars and adjustable shocks. Worked like a charm.

GTA1990

iTrader: (1)

yeah - seems to make sense

the bigger sways should help the roll associated with the non WS6/ IROC setups and adjustable, firmer shocks, should help control the rebound manners.

Jeffs82TA

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I have a 1990 vette with FE-1 soft ride and purchased a 1990 Z-51/Fx-3/FE-7. While Z-51 was brutal springs in the 84-85 era I am not sure what Z-51 was for 1990, this car also carried the same spring codes as my FE-1 however it's sway bars were much larger then my FE-1. Handling was substantially better with the second 1990 however it's ride was about the same.

By comparison, the 90 FE-7 rear sway bar was about the diameter of my FE-1 front one. But compared to my stock FE-1 rear sway bar the FE-7 sway bar made it look like a paper clip. The front FE-7 sway also noticeably larger then my FE-1.

hope that helps that handling isn't always bone jarring spring rates, side wall tire height is a great factor as well. Look into 83-85 WS-6 spring I had a 84 trans am with it and it actually rode pretty nice and still cornered very well.

Think you are just going to have to find a happy medium.

paul_huryk

The stiffer the chassis, the better the suspension can help keep the tires on the road. BMW and MB have been using super stiff chassis for years, allowing them to run less aggressive suspension setups to get good handling and ride.

Also understand that BMW tries to get their cars to a 50:50 weight balance so that there is no built in over or understeer due to the weight bias toward one end. This helps a lot in terms of being able to not manhandling a car on the track to go around turns (same on the street). Never been a fan of MB handling, even though some of the new cars are very capable.

Before you start changing springs, did you install poly sway bar bushings and end links? They made a huge difference to every thirdgen I put them on vs. stock rubber ones.

Also, did you experiment with different sway bar sizes front and rear? I was running a 36mm WS6 front with a 21mm Z28 rear - changed to an 18mm once I put in a 40lb heavier 12 bolt in.

What type of tires (size, brand, and model) are you running? 275-40-17 is a huge improvement over stock 245-50-16 in the same tire...

Lot of variables to improve handling...

GTA1990

iTrader: (1)

Thanks for the reply. And cheers for some real world info Jeff - I'm really thinking about putting in some non-ws6 trans am springs

Paul - I'm actually looking to maintain (possibly further improve handling) and improve ride comfort by getting slighter softer springs due to the stiffer chassis.

Yep - the car has polybushes (graphite type front ones) and end links. Welded SFCs, wonder bar, strut brace, bearing top mounts, koni yellow shocks, tubular panhard and LCAs with pivot joints to prevent binding, LCARBs << all the usual stuff the 3rdgen.org peeps have tried and tested.

I haven't messed with the sway bars - but would a thinner bar improve street comfort (potholes, rough roads etc.)?

I'm guessing for comfort I'd should stay with 245/50/16s on GTAs

Jeffs82TA

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I switched from 245/50/16 tires on my 97 camaro and went with 275/40/17 and the change in ride wasn't too bad. However the handling greatly improved.

Flip 2

iTrader: (1)

I think if you go smaller with your sway bars you will not like the wallowing feeling on corners.

Scorpner

iTrader: (4)

I agree with using softer springs with stiffer sway bars and have done petty much the same with my V6 Camaro Berlinetta and it holds the road a lot better while maintaining the ride quality it always had. It appears that the sway bar links are stressed more with the softer springs and I’ve switched to poly bushing on the sway bar links to maintain the firmness it originally had when I first did the swap. The (Front) bar I have on that one is a (GM) solid and very heavy, but I really like the feel of it. There are a couple of (front) (GM) stock hollow sway bars that are thicker but more lightweight. The more common one is 34mm and the less common is 36mm. I personally like to get a matched set of sway bars, but a few people like to mix and match. All of the stock rear sway bars are solid BTW.

If you’re planning this out, IMO you want to match the shocks with the springs. I would either switch to Koni Reds from the Yellows; or possibly contact a guy named Strano and talk to him about switching to some Billstein’s optimized to whatever springs you eventually decide on. I’m not sure if he’d do something like that but it’s worth a try.
If you keep the Yellows and switch to softer springs you may end up with a worse ride than you had before. I have Koni Yellows on my V8 Camaro with IROC/WS6 springs and the ride is extremely harsh. I have other springs I was going to try but haven’t gotten around to it yet. There is a possibility that you could obtain a better ride by adjusting the Yellows and/or matching the springs to the Konis. You can also look into aftermarket springs that have variable spring rates. This helps with the ride quality as well as handling since part of the spring is softer which allows for a smoother ride while the other part takes over when cornering.

You could opt for the rubber bushings for the front A-Arms as well. But everything else you listed should be ok as far as comfort goes. I agree with staying with the 16” wheels and keep in mind the stiffness of the sidewalls can affect comfort, but not as much with 16” vs. 17’s or 18’s. I also agree with keeping the lighter weight wheel you already have, the SFC’s, pivot LCA’s to avoid binding, and wonder bar.
I’m no expert on any of this, just throwing a few ideas out there that I’ve picked up over the years.

paul_huryk

Look into Herb Adams - he advocated lighter springs with a heavier sway bar combination. Obviously others have done the same, but he is known for racing second and third gen f-bodies and also for street parts.

I am going to point out the obvious - lack of 245-50-16 stock sized tires in high performance patterns available today. One real option is to go 275-40-17 on the proper wheel.

Flip 2

iTrader: (1)

I have a Herb Adams rear sway bar. Courtesy of a TGO member, btw. I love it, but it is honkin' big. It is 80s stuff, not really politically correct in today's handling mantra. Plus you will have to find a used one, I think. Do not think you can get them now.
It is paired with a 36mm hollow GM, on the front. Combo did wonders for my handling. Had Eibach pro kit springs, at the time. (see sig pic)
You want to make sure you don't go past level with your LCA angle- lousy traction- that hurts handling- if you do.
Lastly, it took some work, and a few tries, to get the BIG Herb Adams bar to fit properly- without binding.

GTA1990

iTrader: (1)

yeah the Herb Adams philosophy seems to make sense for road compromise.

interesting point with the shocks. My rears are on full soft but the fronts a bit below midway - blonde moment; maybe I can get some comfort back by going full soft on the fronts.

LCA angle seems ok. Goes off the line well (standard L98) and no adverse snap characteristics on the track - neutral to mild understeer which is great for the unseasoned driver

I think I'll go for the softer springs. Forgot to mention that I'm running on cut springs at the moment (purely for aesthetics) and will no doubt cut the softer springs to achieve the same ride-height. IN a roundabout way, I'd think a firmer chassis and cut springs (increasing rate) will help counter a softer spring in terms of net overall car softness.

I'm also hoping the softer springs will also help with the rattles...

Roostmeyer

iTrader: (3)

Yes the sway bars are going to be part of street comfort. If they're not binding they should have very little effect on things like frost heaves/expansion joints, but once you get to pot holes that only affect one wheel at a time they will cause an increase in that wheels compliance. I'm not in the mood to flip through a book right now so I'm not going to check this statement, but a larger bar shouldn't cause as much NVH as stiffer springs because only half the bars rate is going to affect single wheel bump.

To keep the handling the same you want to keep the overall amount of roll the same. Four things affect this. CG height, roll center height, spring rates, and roll bar rates.

If you want comparable handling after decreasing the spring rate you need to decrease CG height, increase roll center height, or increase the size of the roll bar.

Drop spindles would help reduce CG and keep the roll center in the same place. You should be fine on factory wheels with them. In back you may need to run weight jacks to keep a low spring rate and lower the back 2" as well. LCA relocation brackets may be needed. Cheaper alternative would be longer ball joints and a bumpsteer kit.

36mm/24mm are the largest factory bars. There are stiffer aftermarket adjustable rear bars. Up front the only thing left would be a custom splined speedway setup which would require some fabrication.

If you don't really care about keeping the roll stiffness and responsiveness the same you can increase front camber to compensate for the added roll and call it a day. You can mark your strut towers and just switch between a track day alignment and a street alignment easily enough. The loss of responsiveness could be made up with more rebound dampening.

Jeffs82TA

iTrader: (1)

Try some berlinetta springs for a v-8 they were cushy riding cars.

83 Crossfire TA

iTrader: (2)

The thing you really need to remember in this discussion is that one of the reasons why really high spring rates work on the fronts of these cars is that it they severely limit suspension travel and keep it in an optimum suspension geometry range- with really stiff springs the suspension only has to work correctly in a very small range.

GTA1990

iTrader: (1)

yep, something to take on board. I do prefer it about 1.5" lower than factory which perhaps compunds the need to have stiffer springs.

I'm gonna go with late, cut, non-ws6 T/A springs. I'll be driving it on the road and track so can report back about what I gained in road comfort and possibly have lost in handling



attached a pic of it back in the day on the edge on corvette 18/19s. Looked great, felt solid, but my god was it a rough ride!

paul_huryk

Absolutely right.

Of course, cars with lightened front ends and or coil overs can run lighter springs and still get that optimal range under heavy cornering.