Bit of a long one this im afraid....and its starting to really do my head in now...plus i still havent got to the bottom of the problem and its costing me a fortune. About a month ago i had the front and rear brake pads replaced on my S3 for its MOT, trouble is somewhere along the line a previous garage working on my car had forgotten to replace the locking wheel nut back in my car.... the old locking nuts were therefore probably removed with force when the pads were replaced. When i got the car back, even after going through the normal bedding in process, the front brakes developed a judder under braking which eventually got worse and worse. Believing this was an uneven build up of pad material on the discs, i sanded the discs with garnet paper which improved the problem for a few days only for the juddering to return even worse. So i locate a local garage that skims discs on the car and get it booked in. When they connect the machine up to the drivers side disc, the disc is so far out that the machine wont calibrate so the guy at the garage suspects (correctly as it turns out)that the hub is out of alignment. I can only assume that this was done when the locking wheel nuts were forcibly removed previously. So the long shot of all this is that the hub gets replaced, the discs are skimmed successfully whilst on the car (and are now within tollerance), however even after all this, the car still judders under braking. Its now not as bad as before, and the guy at the garage checked and rechecked the skimming machine in case it was faulty....but its stumped him and he has no idea why its still bad...how can this be??? the discs are now true and have been skimmed on the vehicle so surely this would allow for any error in the hub being slightly out. and the pads are nearly new. I currently have 355mm brembo discs on the car and the guy has suggested that i replace the discs, calipers, pads etc for the standard S3 set up to see if this rectifies it. But why would this help? Firstly i cant see that there is anything wrong with the discs and calipers that are currently on the car,and secondly i cant afford to...anyone have any ideas about what else could cause this???