I have had new rear discs and pads fitted less than 500 miles ago, and last night I had a quick blast up to speeds I hadn't done since the discs had been fitted. I have a really bad vibration coming from the whole of the rear of the car. It is ok up to the ton, but over that it steadily gets worse. I had to back off at 125 as the it felt and sounded awful. When braking the discs are fine and the car stops as it should. Might there be a problem with the discs, or should I look elsewhere?. The vibration wasn't present prior to the service. :dont know: