dogfish246

When I got my new tires put on the guy was asking what pressure I wanted the tires at... I told him 41psi, he said "WAIT WHAT??"

I told him fine, 37psi

brownc00

So, what you are telling me is this: The C4 handles good, just don't hit a bump while you are going around a corner because the car will jump all over, get out of shape and generally do bad thing. This is considered normal and I should live it. If I don't want to live with it, I should buy a lexus.

This could be the worst explanation of a problem that I have ever heard. Perhaps I should make a video of my car.

BADDUCK

You probably can never get rid of that side hop. I wouldn't throw money at it. I have a 1989 Z51 which has a much stiffer ride than your car.

Did you ever look up the suspension code? It should be under the console lid.

Tom400CFI

No ****. I'm guess I need to be more clear.

If you're TRACKING your car, setting a class speed record at Bonneville, or trying to break the ZR-1's 24 hour speed record....you might consider customizing your tire pressure for the task at hand. You MIGHT even consider using task specific tires. In competition environments, I think that we can all agree that "ride quality" is not one of the most important criteria. I'm pretty sure that the OP isn't complaining about his harsh ride, while doing 140 down the front straight. Agreed? I'm betting that the OP probably has slightly different critera than you, PLRX.

However, if you're driving to the grocery store, in a 3300 lb car w/9" wide tires on it, you don't need 35 lbs of air to support that load, and avoid excessive side wall deflection. Is that better? Geezus.

brownc00

Sticker says FE1. I'm fine with a "stiff" ride, but the darting around in/out of the lane when you hit a bump just seems kinda not right. Kinda doubt GM designed the car to handle like that.

Tom400CFI

I think that you should:
Get an alignment w/more caster
Try different tire pressure
get better/newer shocks
Stiffen the chassis.
...and then reassess.

PLRX

well we have different point of views and Geezus is not coming down to soften a suspension or to inflate and deflate tires every time I go to the grocery store. That is why I have a DD.

There are a lot of posts in here but the truth is that (all of the above) is not going to soften a Corvette enough for it not to be "horrible over bumps"

Tom400CFI

Fair enough. I don't think the OP has two 'vettes for two different duties either.

I tried lowering air pressure and it does make a meaningfull difference. When I track my car, I set the pressure appropriately. Not a big deal for me.

BrianCunningham

the 18's in the back are not helping you.

I've run 18s, 17's and 16's on my car. The bigger the diameter the lower the sidewall which does not help ride.

base suspension spring help

I went to dual rate coil overs and it's like the car is tranformed.

Had a C6Z06 owner tell me my car rode better than his!

aboatguy

When my vette was new to me its highway manners were attrocious. Tom400CFI is giving you good gouge.

The vette has been my DD for more than 5 years now and it doesn't change lanes on its own. (Ensure you don't have any worn suspension components. 4 wheel alignment, shocks, proper tires/balance and tire pressure. Will make a world of difference)
Now a while back I replaced my polybushing equipped dogbones with sperical ball end trailing arms and they greatly improved the ride quality without degrading the handling. (Bought them for handling improvement and was rewarded with a better ride too....)


So IMO a C4 can be made to handle and behave on bumps (and beleive it or not Louisiana roads have bumps, potholes and uneven sections)Mike

BADDUCK

FE1 is the softest (standard) suspension. The hop when you hit a bump in a turn is a completely different issue than the tracking problem you are calling darting. The darting is caused by improper alignment, loose parts, or both. The hop is characteristic of all these cars. You can dampen it with different shocks, for instance coil over adjustable shocks etc. Also adjusting tire pressure can help with the darting as well.

socalman

I think your problem is you're running 7 year old (too old) C5 rims and tires, I'm also guessing since the size is too large for your car, that they are the stock Run Flats from a C5?

Ditch the tires, size them correctly (275/40/17 and 285/35/18) and you will stop jumping all over the place (along with less than 30lbs air).

Lrod

I have the same problem with my 96 although it has been relived some what when I changed shocks, replaced sway bar bushings and end link bushings(you can't tell they are worn until you remove them) and new tires(Nitto NT555 today). I changed all this stuff over a period of time and each has improved the "Lane Darting" where it's hardly a problem. The steering wheel doesen't vibrate at speed and I'm not white knuckling the wheel anymore. It may not work for all but it's getting better for me.

coupeguy2001

I'm tellin ya, tires made all the difference in the world.......doesn't ride like my C5, but it rides 75% better than with the 16's.
At least change your front tires, especially if you are running the runflats.
If you have runflats, there could be your whole problem.

Rob31

Id like to see a better pic of your avatar

mfi

I had the same prob, turned out to be dry rotted tires which could only be seen from the inside of the tire...get new tires, put in right amount of air...thats a start. And no ..you don't have to spend a fortune on them..mine where a little over $600.00.

brownc00

Thank you everyone for the advice. Yes, these are the original equipment run-flat tires. Is that bad?

I'm thinking I'm going to start with replacing just the front tires and see how that goes. I'll update the post when I get some tires.

BrianCunningham

yes
yes
YES

the way runcr@ps work is the the side wall is stiff enough to hold the car up w/o any air in them.

regular tires 2psi you can actually feel.

coupeguy2001

Nice looking car BTW.
Just keep in mind that with 2 runflats on the back, 2 new regular tires on the front, there will be minimal rear tire sidewall flex, and your car will tend to feel like it has some understeer going around corners....
But.......the bumps will almost disappear with new tires.

AND, IT WILL BE A LOT QUIETER.
Understand that the tires are like any other component. They work together to perform as designed.
If you compromise the design of the car by mixing and matching tires, it will not live up to the design, both in handling and ride. So don't condemn the tires you buy because you didn't change all 4.
Reserve your final judgement till all 4 get changed.

aboatguy

and lots of performance drivers that own cars with runflats end up running non runflats....