first thing is change your discs, sorted!if you still have the same problem cheak that your rear wheel bearings have no play in them. if there is play in them belieave me all the problems your haveing will be from there, i know , cus i been there, changed steering rack,wheels, disks,anti roll bar, bushes in the steering colume, no good.by chance found nearside rear wheel bearing was loose , sorted that and it was like a different car, hands free at the ton, 3 yrs trying to sort it, and just a rear wheel bearing loose, amazing!!