Jeredk21

I have made many changes to my 98 c5 to make it more track ready. I still don't like the oversteer issues. I was gonna run a square setup with 18s all around. Will the rear z06 wheels fit on the front of the c5 OK and what size tires do you recommend. I was gonna do Hoosier a6

Bad Karma

Lots of guys the C5Z rear wheels all around, you can't turn the wheel lock to lock without rubbing, but on the track and in most driving circumstances you won't have any issues.

As for fixing oversteer, when are you noticing oversteer and what mods have you done already?

Jeredk21

For suspension I have c6 z51 bars all around with solid end links. I am running pfdat front shocks that are adjustable and z06 rear shocks. Also have the z06 springs front and back and car is lowered on stock bolts. It seems to plow when going into a corner at any speed. I just want this thing to stick. I am moving to slicks and installing ploy bushings, hope that helps. I know it is not going to hold every corner perfectly but I want more than what I am getting. I just ordered a lower splitter, I am gonna try added some down force to the front.

Is square setup the best or should I just stick with 17 in the front. Any other things to try would be appreciated.

Thank you everyone and Merry Christmas

C5ZEE06

Suggest you start by checking f/r alignment specs. Maybe f/r rake too.

Bad Karma

I would definitely check your alignment settings and something odd like having toe out in the rear can really bring the car around on you. If you read the sticky about HPDE track car coversion there are some alignment recommendation in that post.

I would give your shocks a once onver to make sure that none are leaking. Getting into the adjustable shoick setting is where you need to know what you are doing so that the car handles the way you want, if the settings are off it can give you some odd driving characteristics.

One of the biggest modifications that made a difference to my car on track was replacing the sway bars. I installed a set of Van Steel adjustable front and rear bars and the heavier bars helped with turn in and helped plant the car, it roates nicely now, but is also very predictable.

Another thing to check on is tire condition and your hot pressures. I've driven on older tires where the rubber wasn't up to snuff and there wasn't really a transition to loss of traction, it just happened. I've also run pressures too high when hot and the got a greasy feeling to them.

Bill Dearborn

Plowing on the front is understeer not oversteer. Your problem may be not driving the corner properly for the car or having the front end too stiff in relation to the rear. Sometimes all it takes is a change in the type and timing of driver inputs to get the car to snap around a corner. It's easier to try changing your driving than it is to change parts so you should think about what you are doing with the car as you approach a corner and while in the corner. What are you doing with your hands and feet during the sequence from initial brake application to full power corner exit.


Stock C5s w a stock alignment have a fair amount of trailing throttle oversteer (backend coming around). Are you getting any of that? What happens when you lift quickly in the middle of a corner and then reapply throttle? Are you able to yaw the car doing that?


Bill

brkntrxn

I'd also recommend against going to A6s. From the sounds of it, I would say you may still have some things to learn about driving and setup. A6s will mask that at a high price and short life.

chetly

Yep, sounds like your car is pushing then going into snap oversteer. Just by going up to 18x10.5 with 315s will help with the push. It might even cause the car to be loose. You could fix that by adding a smaller rear sway are or larger front bar.

I'd also look into getting a full set or shocks. Having matched shocks will help with taking away any variables in shock tuning which could lead to mishandling of the car. Id look into the DRM bilsteins or even a set of Koni's from forum sponsor Sam Strano. Front sway bar could be sourced from Sam as well and is adjustable. I'd also recommend following the SCCA STU builds happening. A lot of good info there and sounds like a direction you might be taking your car wether you know it or not.

As others have said, I'd stay away from the Hoosier A6's. All that's going to do is magnify the handling issues you are already having.

Jeredk21

Thanks for all the info. I did mean understeer, not oversteer. Now that I have a harness in my car I can really feel the car moving as I drive. If I tap the brakes the car seems to correct a little and I can stomp the gas and get the rear to push a bit. I am just not getting the grip I would want. I was running brand new falken azenzis 615k's. They are really great tires and I regularly check pressures. I want to also say I am running in the top of my class with good times I just want more. I am gonna add aero to my car. I know I need a track alignment I am just not sure on what settings to choose. Also it has a slight amount of rake anyone have thoughts on stance height.

froggy47

I would forget the aero until you have a neutral handling car (to you liking). Too many things changing at the same time. A square set up should NOT understeer, as you are already taking away grip from the rear, which should result in oversteer if anything. If you are not running a track alignment - as you last post says, start there. Get a track alignment & then "play with alignment" a while until you know what the alignment changes will result in. Then start with more mods. To add aero to change handling with a stock or near stock alignment is .... You need to do things in a logical order.

Nonetheless congrats on the fast times in your class. Your driving skills are compensating for a marginal car setup.

Jeredk21

Thanks froggy, I watch all your YouTube videos. I know I need to just do one thing at a time, I just have car sitting all winter so I go a little overboard

Bad Karma

Totally agree. Like I said start with what's in the build thread in the sticky for alignment and play with it. I bought a multiyear alignment package through NTB and I bring in my own specs. I've gone throw a few realignments before i found one I was happy with. One felt good through mid turn and on corner exit, but was squirmy under braking, and didn't turn in a crisply.

Then there is the amount of street driving to track driving you do on how aggressive you want to be on camber and toe. I ended putting more wear on the outside of the tires from track driving than I was wearing the inside from street driving, so last go around I went more aggressive and the car feels the best it has (also dropped right height a few turns of the bolts as well).

To really dial in a balance you like that works for your driving style and driving mix, you are going to have to play around with it. Finding a shop that can get you an alignment package to last you a few years and that is willing to align to your specs, and start experimenting.

I also second how good the DRM Bilsteins are, I have them and the feels great with them on.

For your ride height question, do a search there are so many threads on it you can read through. Most seem to agree you should keep roughly the stock rake for being on track. So if you lower the front bolts 3 turn you should lower the rear 3 as well.

Jeredk21

Would you share your height measurements, also your alignment specs. Mine was already lowered when I got it, I think to the lowest on stock bolts do I have no idea where to start

davidfarmer

Align and scale, then dial in with tire pressure and bar adjustments. If you still have push, you need to stiffen the rear

Corvettes are very neutral from GM, if the balance is severely off then something has been done to cause it