CORTVET

My 04 vert is basically factory stock, down to the factory tires.

I replaced my stock rotors with the GM drilled and slotted rotors at my dealer. Now I have a very slight vibration at 80mph. I did not have this vibration before the work was done. You can feel it and see the steering wheel shake very slightly. This is not under braking and only at 80ish.

My service advisor doesn't think that it could be a new rotor causing it, he says that the rotors are balanced when they finish them. He suggested turning each of the front wheels 1 or 2 wheel studs over and trying that. He said if that did not solve the problem, they would road force balance all of the tires. He thinks a rim and tire might have been slightly out of balance from the factory and rotating the rim on the wheel hub has magnified a previously undetectable vibration.

Could it be the rotors, or is my service advisor on the right track? Any other possible causes, can rotor replacement effect alignment? Any knowledge on this would be greatly appreciated.

Thanks,

AZC5

yellow01

Personally the first thing I'd do is loosen all the lug nuts and retorque to 100 lb-ft. I know they are supposed to do this, but after getting my car back and removing wheels for another reason, there is NO WAY the lugs were all the same torque. If you don't have a torque wrench I'd buy one...they're invaluable sooner or later.

Since the only thing that changed (correct?) was the rotors one thing immediately comes to mind for me.

Did they completely clean the hub and the back of the wheel of all rust buildup before installing the new rotor? They should, but if they didn't it could cause excessive runnout. The rust doesn't look that thick but can cause mating issues between brand new parts and the rotor.

Certainly, it can be as easy as them being right and the wheels need balancing...but since all that was changed was the rotors and I'm assuming there was no vibration before, the two things I mention above are what I'd check first.

AU N EGL

I would loosen all the lug nuts then re-torque to 100 ft lbs. Take the car out for a drive and do a few relativly hard stops, 40 to 5 mph do two or three and see if you feel that vibration.

If not do a few 80 to 5 mph stops to finishing the rotor bedding process.

Good Luck

laketullochvette

It would be alot of work,but quite possibly they did not clean the face of the hub that the back of the rotor sits against,if there was just a little rust or debris between the rotor and the hub this could cause a vibration.

CORTVET

Update.

Well, I had the dealer pull the rotors off and clean the mating surfaces, it did not fix the problem. It still vibrates. The dealer said 2 of my stock runflats on the drivers side had heavy spots, which was causing the vibration. They also said that it is impossible for it to be a rotor.

Needing to upgrade my tires anyways, I went out an got some 555's mounted and road force balanced on a GSP9700. It took about three tries on each wheel(turning the tire on the rim) but 3 are under 8lbs and one is 12lbs. Which from what I researched is well within specs(20lbs). They were able to zero out all 4 tires and wheels with weights.

I still have the vibration. And I noticed while backing out of my driveway and turning while applying the brakes I get a weird noise that seems to be from the passenger side rear tire area.

I have an appointment tomorrow to have the wheel hub and brake assembly inspected.

What else can this be? Wheel bearing going bad? Incorrect reassembly of the brakes/wheels? I have 8,000 miles on my vette. Any input would be greatly appreciated.


Thanks,

AZC5

BNLspeedaddict

Put the old rotors back on and see if the problem is still there. At least this way you can verify it truly IS the new rotors causing the vibrations. Good luck.

CORTVET

Yea, I just dont know if the dealer still has my old ones. I will mention it to them though. At this point I am willing to try anything.

Thanks,

AZC5

csexton

Good luck and keep us posted!

VMI07

Had the same problem but more severe. I mounted the wheel on the car spun the wheel and hand tightened the lug nuts constantly shaking the wheel. I think all the comments you received are right on except for the fix. The process ensures that the wheel is flat on the hub. Once all had tightened then torque to specifications.

good luck

CORTVET

Update-


It turned out to be one of the front rotors. It was some how out of balance from the manufacturer. I replaced all 4 and the vibration is gone.

Thanks for all of the suggestions.


AZC5