I love my new C5 Coupe. It has 10,000 miles on it (2001). I have one small issue/question, when I go thru rough road areas or concrete jointing, my rear and front end jump sidways. I am not even hitting the curves hard. In the rain last week I nearly lost it going 45mph on a 55 mph ramp. It only seems to happen when I am turning left. Is this an alignment issue? Any ideas or similar problems?

 

It's your EMTs. Get some better tires, and it will dissapear. It use to annoy me to....

 

Hi Shannon, I would say the same thing. My EMT's have 25,000 on them and they are jumping more with every mile! Mike

 

 

Oh, yeah.... Welcome!


(er, nevermind, you've been here a bit, still... welcome anyway!)

 

i am not so sure switching tires will help all that much. i originally had the stock runflats and switched to new CCW wheels and pirelli p zero rosso tires of sizes 275/30 and 305/30. When I follow a hard line on ramps and go over seams in the concrete I still jump sideways. I think it has more to do with physics that tires. I same thing doesnt happen with other cars I drive simply because I cant corner as fast.

 

Good non-run-flats and 04 z06 shocks will cure problem.

 

Damn, I was hoping I wouldn't have to throw any cash at it, hoping it was some small alignment. Oh well. I will say that I am getting better at managing and anticipating the hop. That may be the best answer short term, and tires long term. Thanks so much guys for your input. As usual CF rocks!

 

I have new Michelin Pilot Sports run flat and Z51 suspension and it still does it. When I watched the speed channel test drive of the new Z06, it looked like the front end of Jeff Gordon's blue Z hopped around a left turn in Atlanta at about 70 mph. I just think that the 50/50 weight distribution allows the front end to get loose around turns with uneven pavement. If the weight of the car is transferred to the back due to acceration the front end will hop around a turn either way. When I enter the same turn and apply the brakes to transfer the weight of the car forward, I can take the same turn better. I never had this issue with my 98 camaro but then again, that car was much heavier and a lot more front heavy than the vette. jmho

 

It is typically referred to as bump steer. I agree with most of the posts above. It is part the EMT's and part physics. The tire is an integral part of the suspension system. The runflats in order to accomplish what they are intended for have an extremely rigid sidewall. A softer, non-runflat tire will flex more in the same situation than a run-flat and consequently transfer less of the impact up thru the suspension. I don't know what suspension option you have on your coupe but a Z51 will probably exhibit more of this than an F45 on touring mode. The age and mileage of your tires will play a part as the more heat cycles the tires have seen the stiffer they may become. With all of that set corner and weight management have a lot to do with it as well. If you are setting up for the corner try to have the suspension as neutral as possible (not hard accelerating, not hard braking) at the point of the bump. This will minimize the weight transfer that will react to the impact. The sporty suspension of the Corvette is just a bit more sensitive to the bumps in the road than that of the typical sedan. I doubt an alignment will cure what you describe.

Paul

 

Wow Paul, thanks man, much much help. I am thinking that this car sat in a garage most of it's first four years. These tires haven't seen any action. I wonder if they aren't alot stiffer than if I were to buy new.

 

Replacing your runflats with non-runflats will save you 24 lbs of unsprung weight, greatly alleviating side-hopping. It won't go away completely, but you will feel much more secure. I recommend Goodyear GSD3s - excellent tires!

 

Awesome, thanks!

 

I believe the problem is the transverse mono-spring used on these cars. The suspensions are just so stiff with this type of setup. My C2 now has a vbp mono-spring set up on it (just like a c4 or 5). Guess what, now it does the same thing as my 01. I don't think there is any way to cure this problem. I doubt very much tires are the answer, may help some but not by much. Just my 2 cents, but I am new to the c5 crowd. sixty4.

 

Mine did that from the day it was new. When I swapped out the Goodyears for Michelin runflats, I don't notice nearly as much.

Jay

 

If you still have the stock runflats, it's as bad as it can get. Better tires will help, either a non-runflat or a softer runflat like the Firehawks will make a big difference. But mostly, the reason for this is there just isn't that much sidewall between the rim and the road. There just isn't enough tire to flex enough to totally absorb the bump. Some tires will be better than others.

 

Could be wrong but I have the firehawks(which are noisey at low speeds) on my 01, and have driven ones with GY run flats. I still feel it is a suspension issue( lack of rebound ) That makes the car hop. I have yet to drive one that does not have this hop. sixty4.

 

Happens on my Z06 if it encounters a bump during a aggressive turn. Sort of hops sideways a bit, sort of reminds me of my solid-axle camaro

 

Thanks for the explanations - it all makes sense to me.

As a newbie C5 owner I noticed and wondered about this too, and dismissed it as just a characteristic of the car. I'll have to put up with it until the remaining 75% of the runflats tread life is gone, but it's good to know this is another of the annoying traits I will be rid of when I get new/different tires.

I can't help but wonder, with so many undesireable traits, what the hell were they thinking when they selected these tires for this car???

 

Try this...
In a corner outside (or inside) tires go over a seam, crack, etc... The adhesion of the total package (all four tires) goes down... car looses grip... jumps sideways until the tires collect themselves and provide grip again...
What you have done is approach the limit of adhesion and then the road (crack, strip, etc...) causes the limit to be exceeded and the whole car jumps. It doesn't happen on your wife's Cadillac cause you are nowhere near the limit with that truck...
The more you drive the Vette, the more you use the Vette... right up to the limit you have never experienced before...
WELCOME!!!!!!!!!!!!
Aint life with a Vette FUN!!!!!!!!!!!!
ZOOOM