tertiumquid

I have a 2016 ZO6 A8 Vert. It’s only used on the street and has just over 10k easy miles. I’ve had problems with cracked and bent rims which I’ve pretty well solved by going to forged wheels and Continentals. It handles much better and is a lot quieter. However, it originally had a vibration problem which, given the shape of the wheels and tires, I assumed was the cause. But, even with those changes it still has a vibration that starts around 40 mph on a smooth road and the best way I can describe it is that it feels like an older car with a bad U-joint. Coasting in neutral at that speed with the engine idling does not make it go away and it doesn’t seem to be coming from the front or rear specifically but you can feel it mostly in the seat. The engine runs smooth at all times. It is obviously a rotational problem of some sort and while not terrible, it’s definitely annoying. I previously had a ‘16 Stingray with 18K on it and never had this problem and I’ve read that the ZO6 does normally have a harsher ride but I don’t think that’s the answer.

I have a Range module in it so it’s not the V8/V4 mode issue although that was installed only recently. The converter was drained and refilled with new fluid a couple K miles ago by the dealer and that fixed a hard downshift problem. The vibration occurs in any driving mode from Weather through Track.

In reading through other threads, this seems like it might be a torque converter problem but I would think that coasting in neutral would eliminate that possibility. Or, does this maybe involve the MRC system and might be fixed by the re-flash? Before I drag it to the dealer and go through two weeks of waiting and wondering, does anybody have any other thoughts on what this might be? I love the car but this is getting a little frustrating. Any advice will be greatly appreciated.

djnice

Maybe a bad rear wheel bearing or u-joints in the rear axle.

LagunaSecaZ06

Before doing anything else find a shop that has a Hunter Road Force balancer and is willing to index the tires to the rims based on the road force readings. If this does not solve the problem then look at other potential areas.

tertiumquid

Thanks for the response but they were already run through a Hunter and everything was fine. This problem existed before I changed the wheels and tires, so even with a completely changed wheel setup, the same symptom exists and therefore it has to be something else. I've been a trouble shooter in electronics for 35 years and played with cars for 60 years. The one thing that's always for sure is when the problem is finally found it's usually something simple. The problem is in finding the needle in the damned haystack.