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.