I am a new member with my first Corvette, a 2002 Red Coupe. I love it. Recently I bought a set of new C6 ZR1 style wheels from a speed shop here in Florida. I put new Nitto Extremes, 255/45-ZR17 and 285/40-ZR18, on them. I have had the car at 2 different tire shops trying to get them to stop shaking at 60mph. Has anyone had this problem and how do you tell if it is the tire or the rim? I'm pretty sure which wheel is causing the problem, but I'm not 100% and the shop bills are piling up.

 

Wheel bent or tire out of round? Did they check for that?

 

Start with the rims.

 

Could be your wheels are bent/out of round or the tires have a problem. A good shop should be able to pinpoint the problem.

 

Why keep taking them to different shops? If they vibrated after the first balance I'd return to the shop and explain the issue. Request a rebalance or a refund. If they can show you the wheels and tires balance on their machine you may need to look else ware for the cause of the vibration. Good luck.

 

 

Check to make sure the sheet metal "speed nuts" are not still holding the brake rotors on (usually two per wheel). If they are some wheels will not seat flat on the rotor hub. Causes a lot of shaking. Have a look and good luck.

If the brakes have never been done on your car you can almost be certain the speed nuts are still holding the rotors on. On the back of the factory C5 wheels of all variations there is a reveal cut into the rims that allow them to go over the nuts. If you still have the original wheels just look at the back of the lug nut holes. You will see the machining work done. Many aftermarket and perhaps factory wheels from other later versions of the car may not have this feature.

My CCW wheels did not have the relief cut into them and I had exactly the same issue until John at CCW asked the question about the speed nuts. The man knows his stuff.

Worth pulling a wheel off to have a look. Again good luck.

 

x2

 

I had the same issue with my C6 ZR1 wheels on my C5, I took the car to a reputable shop and they performed a Road Force Balance and the problem was solved. Not all shops do that so make sure they have the proper equipment. Good luck and hope the issue is resolved soon.

 

You just came up with an interesting possibility. Sure would make for a terrible ride (at 60mph).

 

A "balance" problem will come in and out as speeds change. So- it might be smooth at 55, vibrating at 65, smooth again at 75.

An out of round issue (either wheel, wheel to hub/rotor, or tire) will start at a certain speed (when you notice it) and continue to get worse as speed rises. Vibration at 65, worse at 70, still worse at 75, etc.

No amount of balancing can fix an out of round wheel, tire, or combination of wheel and tire. Of course, a cheaper wheel is more likely to be out of round, but any wheel manufacturer will have every wheel tested for out of round before it leaves his factory. It's just that a cheaper wheel will have a larger allowable tolerance so fewer wheels get rejected- higher tolerances, that's one reason they can sell for less.

Now- a possible saving grace:

The wheel AND tire are never perfect. If you have the "high spot" of the tire at the "high spot" of the wheel, the out of round is magnified. You can rotate the two to be opposite each other, and negate the effect.

So:

1. Mark the original position of the valve, on the tire.
2. Dismount the wheel/tire.
3. Run a runout test on the wheel.
4. Re-mount the tire BUT have the tire mounted 180 degrees to its original location. Rebalance.

Test. Most of the time, your problem is eliminated. You still have an out of round situation- but it's hidden by the suspension.

If you use the car on the track, though, don't buy cheap wheels!!!

 

When your checking for the metal clips on the rotor / stud, do a good inspection on the wheel hubs. There should be little or no lost motion if you do a push / Pull test on the wheel/s and check for loose HUB BEARINGS.

BC

 

Ditto!!!

 

http://www.motorweek.org/features/go...orce_balancing
I had to look it up. Interesting. I doubt if the tire shops I use have that equipment.

 

I found those and removed them. The shops both say the tires are balanced. They drive the car and say they cant feel the vibration. It is a big enough vibration that I feel it without any problem. I wasn't there when it was taken to the last shop but I will be there tomorrow when I take it back. I talked to the shop manager yesterday while the car was there and explained it only happens between 58 and 65. I guess I will have to take him for a ride.
Thanks for your input.

 

I have never heard of that type of balancing. I will look around town for a shop that does that. The last shop doesn't do it, I just asked.
Thanks.

 

I dealt with the same issue, over and over on a set of chromed Speedline stars that some dirtbag on Craigslist sold me. They actually zeroed out, but a sharp tech at Discount Tire noticed that a couple of them were out of round, by simply lifting the safety shield and watching the tire spin- You could see the slight wobble. An out of round condition can happen to soft, spun-cast wheels like the Speedlines when you hit 'em hard enough on potholes, and cause a side to side that balancing won't fix. Got rid of the soft and bent Speedlines, and put on a set of GM (forged Alcoa) polished stars that I sourced from SVT Bone for a great price. Now? Car is like a Cadillac at 75 with the cruise on.

 

Did it make a difference?

 

Thanks for the link. I watched the video. It explained why Road Force Balancing is needed and how its done. Hope it works

 

They were only on the front. My new wheels do not have the indention to allow for the star nuts. I couldn't tell if it made a difference removing them. I think my biggest problem is still in the right rear. I will try Road Force Balancing that one and see.
Thanks.