zeeohsixer

I've read where several zr1 owners have encountered the same shimmy between 70-80 that I have. Chevrolet has a new procedure to reduce or fix the problem. First you've got to have all four tire/wheel combinations to achieve 12 pounds or less via road force balancing. If that doesn't cure it. All four brake rotors are to be balanced with the weights indexed on the wheel in line with the rotor. So far I've had two rotors out of balance by as much as 1.5 ounces. I'm thinking that's gonna make a huge difference. Why are they so out of balance? I'm thinking Italy's quality control has lapsed with the ramped up production of these ceramic rotors. The cooling vents seem rough and poorly bored. Hope this works. I give mine a test drive tomorrow.

Dicecal

Good info, I have the problem with my car. Already took the car in for the road force balance, did not help much. Had the car aligned, and that did help quite a bit. (Factory alignment was way off!) Next I'll go back to the dealer for the rotor balance, gonna drive it for now and see if it gets better as some have reported.

Leroy Amy

Please explain how rotor balance and indexing is done.

Thank You

Torched

Please follow up your post how the outcome is.

pcguy2u

zeeohsixer

Please explain how rotor balance and indexing is done.

Thank You


The mechanics balance the rotor on a regular Hunter wheel/tire balancer as if there were a wheel only configuration. The weights are place on the wheel indexed to the location on the rotor in line and outboard of the rotor.

I'll let you know if it worked as soon as I get a chance to test drive it.

I drive a silver 2011 zr1 by the way.

range96

So, as soon someone removes the wheel/tire and does not know about the indexing you're back to square 1?

Most people with the vibration problem reported that after a couple thousand miles on the tires the problem went away. That means the problem was with the tires.

DannyKing

Had the same problem with mine but totally gone afer the first couple hundred miles

zeeohsixer

Well, it worked! Smooth as a baby's butt. Tires probably contribute but the main culprit is the rotors. They were out of balance. One rear rotor was out 1oz., the other 1.50oz. One front was .25oz. out the other .75oz. It's amazing to me these rotors got by quality control so far out of balance.

OnPoint

Odd deal. Mine's a 2010. 4000 miles. Has never had this issue. Many others have not had it either. Yet several have.

So, apparently a bad batch of rotors that wasn't true/in balance got out.

Reciprocal

I think they all do it potentially, and don't think it's balance as much as harmonics. Bad balance is bad balance everywhere, not just 70-80, There's a natural resonant frequency that gets excited, and since it seems to go away on its own for a lot of people after some break-in, it could be tires or brakes wearing in. I've felt this vibration too, yet at other times at the same speed different day, no vibration.

Dicecal

Has anyone seen the TSB that addreses the new procedure? If so, can you post it? Thanks

YWZ08

I have a late model 2010 and no shake so far.

Torched

racer10

Maybe GM should do a re-certification of all their existing inventory before owners have to discover this quality problem on their own.

Torched

Wishful thinking but this is not the 1st quality control problem right out of the box. I've experienced others with an 08 Z06 I once owned. GM may be reinvented but same old BS passed on to the customer happens a real shame. GM still has a long way to go in customer satisfaction.

racer10

GM will respond if corvette owners stop making excuses for them and stop buying. It is unreal how many corvette owners are willing to accept poor quality in the name of its a corvette and look at all the other wonderful things it can do, therefore I can overlook this problem or even fix it myself.

zeeohsixer

As far as I know this latest fix for the problem has not been published in a TSB. I'm sure it won't be long before it is after a few of us have had good luck with the procedure.

As far as I'm concerned, this procedure is simply a band-aid and all customers who've had this problem should have new certified balanced rotors installed under warranty. Anything less is unacceptable.

racer10

I agree,until then enthusiasts should stop buying any inventory that has a hint of this problem in order to get GM to correct current and future inventory already in or about to be in dealer showrooms and also recall all ZR1 's( as they did for the 2006 Z06 roof adhesion quality problem) and properly eliminate this problem and its possible reoccurence.

racer10

By the way maybe someone should post a You Tube Video of the ZR1Steering wheel vibrating at 75mph.