Hope someone can give me some ideas. I have a vibration that starts at about 65 mph and gets worse as I increase speed and never have gone abovet 100 in case it falls apart. Shifter starts getting noisy and by 75 mph you can feel it in the butt. I've had the car since 74 and everythings original with 70K on it. I had the half shafts and drive shafts checked and were OK. Trany was rebuilt due to leaks and was fine after that many years ago. This has been this way for about 7 years but now it's starting to bother me. I only put about 2K a year one it. Someone told me it could be the front balancer on the engine. If I push the clutch in at 70 it still vibrates but is better. Had the wheels checked but still there. Anyone have any guesses of where to go to next.

Were the wheels and shafts checked for balance, or just a visual inspection? Just asking because wheel balance came to mind first. Make sure wheels are spin balanced, it's much more accurate than static balancing(if anyone even does static anymore ). Any new sounds to go along with the vibration?

|UPDATED|7/5/2003 9:10:48 PM|/UPDATED|

vettman,
I would like to add to privategods troubleshooting tips.
Jack up the car and check for any movement in the wheel bearings by grabbing the tire top + bottom, then side to side trying to see if there is any freeplay. (this will also allow you to check for freeplay in the ball joints and tie-rod ends on the front end.) Slowly rotate each wheel by hand and feel for any roughness. They should feel smooth. Check the "run out" on the rotors. No more than .005" run-out. Slightly warped rotors may cause a high speed vibration. That's my .02 cents
Good Luck! Sarge

by pushing in the clutch at speed and the vibration continues make me think that its driveline related...ie driveshaft to the tires. try rotating the tires and seeing if it makes any difference. also check tire runout, i have see radials that have high spots in the tread area from belt seperation, they will balance fine but will cause problems

Most of the replys already covered what I thought it might be. I will mention one more thing, and God forbid it is not that. If your frame is bent or warped from a previous accident, the car will not track true down the road. I hope that is not it, but I thought I would mention it any way. Jimmie

could just be a bad tire, sure your ujoints are good ,transmission mount rubber , engine mount rubber ,
bad shock that usly just whell hop,I'm going with tire or ujoint shaft ballance,................

Check for a separated tire on the rear. Put the car on a lift and spin the rear tires. If the tread "wobbles" that indicates a separated tire.

go to a alignment shop that specilizes in corvettes..get a 4 wheel alignment. thats the first thing i did when i bought mine. check the # of shims behind the front "A" arms. there should be the same # on each side. also there is a adjustment for the rear alignment, but there are limits on this you may be up to the limit but need more movement. check A arm bushings. i replaced all 8 before my alignment was done.

Thanks for all the support on my vibration. I now have made a list of the items that you have mentioned and my car is going to a brake and alignment shop this Monday. I have given the list to be checked. I bought new OEM rims last year thinking this would take car of the issue since two rims were slightly out, but still had the vibration. I'll let ya know what the outcome is. This has now become a issue of don't stop until it's fixed but hide the bill from my wife. This is my child not hers. She does like driving it but thinks I spend too much time cleaning and polishing it. Oh yea on the one reply the car has never been in a accident. If the list doesn't cure the vibs I'll be back for more ideas. Thanks to everyone for helping me in my frustration.

Some brands of tires start to create vibrations as they wear down. I spent 2 years tracking down a vibration which would start at about 65 mph and get scarey at 90 mph. Wierd thing was it was less in neutral, but still there (rear driveline disengaged reduced it enough to seem like it was going away, but in fact it was only lessening it). I did the 4 wheel alignment thing at the best vette shop in Md. I had all 4 tires rotated and dynamically balanced (they still had about 50% wear left on them). I also rebuilt the rear suspension (it needed new Ujoints too). New tires finally did the trick. This was on my C4 BTW. Damn tires were the problem all along! Go figure! ~Juliet