dhirocz

I have a serious traction problem in my '94 Z28. I've upgraded all the worn out parts and still have a pretty significant problem. Getting on to the questions...

1. Is there any problem with running C5 wheels (18's/17's) that would affect weight transfer to the rear? The stance is good but it's higher in the back because of the 18's and I'm afraid my weight transfer is suffering because of it. I'm considering 17's in the back now if I can find a place to widen my rear wheels. That is, if front C5 wheels will fit in the back. Not sure of the backspacing.

2. I upgraded from the ****ty decarbons all around to the adjustable QA1's on the front, still with eibach prokit springs. Should I consider a rear upgrade as well? The rear seems pretty soft. The front was as hard as a rock. I like the ride height though.

3. I've been running EMT tires now for awhile and have noticed a harsh ride. I've replaced everything but I still have a vibration at 75MPH. Is it possible or have any of you seen front hubs go bad?

Thanks in advance.

Injuneer

How much higher than stock is it sitting? Why is it higher than stock? With the correct size tires, it will sit exactly as stock.

What kind of traction are you looking for.... straight line or general road use, including cornering?
The QA1/Eibach Pro-Kit combination is horrible for the rear. It results in a poorly controlled, very "chopy" ride, sort of like a slammed S-10 rolling down a bumpy road. Personally, I feel the deCarbons are a fairly decent street shock. The QA1's are only good for straight line traction, no better than the deCarbons on the street. For straight line traction the QA1's work well with stock springs.

The EMT's may be part of the traction problem. They work well on an IRS 'vette, but who knows how they work on a solid axle car? And for straight line traction, the sidewalls are going to be too stiff.

dhirocz

It looks like it's about 1" higher in the back. I guess that would make sense. It doesn't have any additional clearance in the wheelwells. It's just higher. I have no clearance issues with my 3" true duals. However they are using the stock size corvette tires, p275 40 zr18 rear and p245 40 zr17 front. I have some new BFG KDW G-force T/A's I was going to put on before I deployed. Want to make sure the right parts are waiting on me before I get home =)

I want some cornering, but I also want more straight line traction as well. It already has LCA's and brackets on it with an APHR and the prokit springs front and rear. And it's getting ready for a full front end rebuild as well including hubs (which I hope is my vibration problem)since they have 200k miles on them.

The front was way too stiff while the rear was way too soft. I'm hoping I can adjust the stiffness down some with the QA1's to be a little softer. I dont want to get rid of the eibach's because I like the look and I know that's a poor reason but I expected more. It rides firmer than my iroc with all poly bushings. I'd rather gain cornering ability from swaybars IMO.

Injuneer

The stock tire sizes on a Corvette are really 2" larger in diameter in the back than in the front?????

Front:
245/40-17 = 24.71" = 1" smaller than a stock 4th Gen tire

Rear:
275/40-18 = 26.66" = 1" larger than a stock 4th Gen tire

Certainly explains why the back end sits 1" higher than the front. The preferred tire sizes for an F-Body would be 275/35- or 285/35-18 in the back, and 245/45-17 in the front.

You could stay with 275/40-18 in the back to provide a taller sidewall for straight line traction, and go to a 245/45-17 in the front to cut the height difference to 1" on diameter and 1/2" on ride height.

Severous01

i'm running qa1's on all 4 corners and i dont really have any problems...no wheel hop, no choppy feeling or whatever. i run stock rear ws6 springs with no isolators (i put waterhose over the spring to cut squeaks). i'm running 17" z06 wheels but if you're running the 18" you'll need 275/35/18 or 295/30/18 depending on a width.

decarbons suck...replace them

i'd suggest some nitto 555r tires or i have bridgestone potenza re730s. they dont make the 730s any more but i've heard the s03 is a nice tire. if you can find them firestone firehawk sz50 are some awesome tires and fuzion ZRi has the same tread compound and technology but are only 100 a piece. i run zris in the rear and i love them. i'll be replacing the potenzas soon with fuzions if i can't get a good deal on nittos.

you might think about talking with sam about the spring shock combo. he'll set that up great since he has the revalved bilsteins. he'll get you the right springs to match as well.