I have been Autocrossing today and I am getting a lot of rear wheel chatter whilst racing. It has been doing it for a while but it has got considerably worse.
When I corner and the load lightens on the inside wheel it starts to chatter or skip really badly when driving on the edge just before the back end brakes loose.

Any ideas what may be causing this, I hear it might be the bearings. I am going to rotate my tire front to rear and will check the wheels feel secure and have no play. Any ideas on what else to look for or what might causer the problem.

The car is stock with Mazdaspeed (lightweight) wheels. I have about 1.2-1.5 degrees of camber on the rear and running Star specs. I have also re-drilled the sway bars to shorten them a little bit.

 

Install a set of progress sways
Done.

 

I think the problem is more than that as I had a guy who also owns an Rx8 drive it today and he really wasn't happy with the chattering.

I have just flushed the oil in the rear diff and reduced the camber to less than 1 degree on the rear so I can get as much tire on the ground as possible. I will see how it drives at Autocross tomorrow.