racinjason424

Hi guys/ gals, I just recently bought my very first C6 and I am fighting a losing battle and I am very disappointed.. The 2012 GS Coupe I bought was spotless inside and out.. 8500 miles, virtually a brand new car.. Until you drove it.. Local city driving is perfect.. Get on the highway and that is where I first discovered the problem.. Once you hit 68+ mph, there is a vibration in the steering wheel that is so annoying for a new car.. It's not a continuous vibration, its almost a whomp, whomp, whomp.. I don't know exactly how to explain it, but its like pulsing or oscilating.. It does is from about 68 on up to well over a hundred.. Seems to get really bad about 75 where I mostly drive.. Sometimes 85-90 is perfectly smooth, other times it shakes also.. Ive had the car up to 135 and it has been smooth, but vibrates at different speeds up and down.. 70-80 seems to be the worst.. Anyway, right after I bought the car, and after I noticed the vibration, I went to discount tire and had the wheels balanced. Didn't help.. I called them back and spoke with the manager and he suggested having it road force balanced.. Never heard of it.. I goggled it and found that my local Chevrolet Dealership did this service. Perfect!! I took the car there right away.. They road forced the tires and it was no better.. They said the front tires were slightly worn on the inside edges and that could be the problem. They also checked the alignment and it was spot on. After they checked and road forced the tires again, the vibration was still there. They recommended new front tires as they were worn 6/32 on the outside to 4/32 on the inside.. I bought brand new GY F1 runflats to replace the OE fronts and had them install and road force again.. This did help, but only about 25% better.. After spending about $2000 and 4 trips to the dealership chasing this problem, I am lost.. They are lost.. Don't know what to do next, but I know something is not right with this car... It has 8500 miles, brand new tires, that have been road forced and it drives worse than my C5 I just sold with 80K miles on it.. I would appreciate any suggestions on what I can check or try next.. Thank you all. Jason

racinjason424

Wheels are also brand new and factory installed. The car came with aftermarket ZR1 wheels, so to eliminate this as a possible cause, I bought brand new GM Grand Sport wheels.. So wheels and tires are brand new.. What else could be out of balance?? Hub? Rotor? Wheel Bearings? Is it possible I need to have a tire and wheel expert other than the dealership re-balance? Maybe they are close, but not close enough? I'm grasping at straws here.... Thanks, Jason

PMD C6

I have the same problem around the same speeds with my Z06.

racinjason424

Have you tried anything specific to fix the problem?

Cyber Greg

See if the dealership can try swapping out the wheels/tires combo one corner at a time with something they have at the shop they know is correct. It's most likely a wheel or tire problem. It sounds like you've tried everything so to totally eliminate the wheels/tires as a possibility this is a way to go.
Do you have MRC suspension? Have the brakes been checked? Has the leafspring been checked?

How is the alignment? Does it track straight? Other than the steering wheel hop, does the car feel smooth or rough?

pcolarossi

How about the wheel bearings or brake rotors?

MARSC6

If it were me I would have the tires balance checked by another shop.

Your problem sounds exactly like a tire out of balance.

fasthwks

I had the same problem with my ZR1, known issue with these and it is out of balance rotors, same speed ranges that you have. I have not heard of these rotors having that issue but just a thought.

MGretz70

Have the exact same issue, but mine just started after getting new rims put on, and have taken it back once already for the problem and still has the vibration. Going back a second time again here shortly. ( Did not have the issue prior to having new rims installed )

VETTE-NV

That sucks. I'm sure it's driving you crazy.

From my experience, I've had several different sets of wheels/tires on the five c6's I've owned and getting them balanced properly has never been a problem.

I did, however, encounter a vibration after I installed Baer rotors on my 2006. It wasn't severe and only showed up between 46 and 50 MPH. The dealer changed the front wheel hubs and it made no difference. I finally upgraded to a set of Z06 brakes and it seemed to go away about 90% but not entirely. I sold the car before solving the problem completely.

Ultimately, it could be many things but if your car is still under warranty, I would make the dealer solve the problem.....even if they have to call in a factory rep to deal with it. Since it seems to be intermittent, I would have them check the torque tube and harmonic balancer.

racinjason424

I tend to agree that the wheels and tires, both being brand new and balanced by two different places, both conventional and road force, may not be the problem.. I've had tons of sports cars over the years, including 4 or 5 other vettes, mustangs and vipers with wide/low profile tires and I've never had this issue.. I think it may be something related to brake rotor, hub, bearing, torque tube or balancer maybe? (something that spins)

Seems to be a common problem though from the responses. I was hoping someone would step forward and say "mine did exactly that and it was this!" Lol..

As much as I hate to leave the car with them to play with, I think the best bet might be to leave it in the dealers hands to check and correct everything under warranty.. The have all the specs, books and resources to do so.. I just wish I could tell them what the problem is so they don't tear the car apart limb by limb doing trial and error..

Thanks for the responses.. Anybody else have any ideas or similar issues/ stories, please chime in. Great technical forum and great group of users. Thanks, Racinjason424

Okconl

Look for bad bushings in the front suspension. OP, shouldn't your car still be under factory warranty?

Quick Silver Z

I vote brake rotor(s).

myfunz

You could have a bent rim.

icntdrv55

The problem you describe could be several things. Certainly, the first item to check is wheel/tire balance, and you've done that. Since you had the wheels checked by Road Force system, I presume that eliminates the possibility of either a bent/out-of-round wheel or a flat-spotted tire, but I'd look hard at that cause again before I spent more money. Lastly, if the 'thump' feels more like it's being transmitted thru the floor/seat/pedals vs the steering wheel, its most likely in the rear, which brings driveshaft/torque tube/rear axle assembly into the mix. Here, I'd suspect that either something is bent or a bad universal/CV joint. Another item to check would be the cushion mounts for the engine and transmission/differential. If one or more of these are worn/torn/loose/broken, it can make a slight imbalance far worse. Good luck!

1968swbbigblock

Rear tires which have not been replaced might be an issue.
The front tires that have been replaced, might have a bad belt even though they are new.
As mentioned above, speed specific typically indicates anything that rotates or is attached to the rotating assembly.
I encourage you to try another shop, some are better than others.
Reset the alignment to Pfadt or similar alignment speciation's as your tire wear 4/32 x 6/32 typically indicates an alignment issue. I know you just had it aligned but if the shop used factory specs with the Good year tires the Pfadt specifications seem to be a better more forgiving alignment specification. It is also helpful to compare the specs that they had after your last alignment vs what they will see today on a different machine.
Consider replacing the shocks as a vibration issue will destroy shocks in short order.

Jim Barker

Aftermarket rims may not have the proper cut inside at each stud to allow the speed nut that holds rotor on to clear the face of the hub and allow the wheel to sit against face right! Most just remove the speed nut and pitch em.

Blazin383

As was asked in one of the previous posts, is the issue manifest through the stearing wheel or thought the floor board or seats? If you feel it through the seat or floor more than the steering wheel, it's likely coming from the back end where you havent replaced or rebalanced tires and wheels. It could be a seperated belt in a rear tire or out of round rear tire. If it were me I think I'd go easy on the high speed runs until I got it figured out.

MGretz70

Those were removed when I got the calipers powder coated and painted the hats on the rotors. Vibration was there prior to taking off the speed nuts and after too.

Jim Barker

[QUOTE=racinjason424;1586619998]Hi guys/ gals, I just recently bought my very first C6 and I am fighting a losing battle and I am very disappointed.. The 2012 GS Coupe I bought was spotless inside and out.. 8500 miles, virtually a brand new car.. Until you drove it.. Local

The fact that new tires on the front helped a little bit and the steering wheel feel is where you feel a problem, still sounds like problem is in the front. Tires are a big problem and there is a max amount of pressure spec that road force should not exceed to make a tire turn true. This spec givin two ways is a problem PSI or Metric kilograms per sq. inch. You need to find out which the tire manufacture uses. And make sure the Mechanic is using or converting to the same reading.

My 2012 GS always seems to take some time to get the tires warmed up and running smooth. They seem to flat spot like the old nylon tires did.