I own a 2002/52 Jaguar XJ8 and for the past 12-18 months have had a recurring problem with juddering when braking at speed in excess of 30mph. I replaced the disk with non-Jag parts and the problem recurred within 3 months. These were replaced by my garage under warranty but again the problem recurred within 8-12 weeks. I then replaced these with genuine Jaguar discs and pads in early August, and once again the problem is recurring. On the last visit to the garage I was assured that all components in the brake system were working properly (callipers etc). I am dealing with a garage that I trust and have had excellent service from them for the past 7-8 years (Specialist Cars of Shrewsbury, by the way). I can't believe there to be such a series of defective parts so feel something else must be the cause. There is some wobble in the steering at around 60-70mph, so I acknowledge the front wheels need balancing. 3 years ago I was rear-ended which resulted in the whole back end being replaced. Since then I have had wheel bearings changed, suspension bushes changed (maybe as a result of the accident). I have not had the tracking checked but can't believe this to be the source of my problem.
The reason is probably bits of dirt between the discs and the hubs that result in the discs running very slightly out of alignment. The answer is to take them off, wire brush and thoroughly clean the facing surfaces, refit the discs, then have them skimmed in situ.
Answered by Honest John on