I have had my 85D for 13 months. Early on I would hear a loud clunk. Then it went away most of winter. Weather is warming up and the past two days the noise has returned. It is a single that occurs if i accelerate hard. It comes from the back of the car and feels as if the axle was lose and banging into something. Can be either forward or in reverse. Happens less than 30% of the time. Usually I am going under 10 mph and then I hit the accelerator. I was a single clunk and then all good. About 2-3 months into ownership, I took it to SC. Of course the noise did not occur in their hands, nor with driving them in the car. Any ideas?