It's been almost two years since I installed 4 wheel disc brakes on my Speedster (74 VW chassis). I have an IRS rear axle and since the brakes were new, the right rear has always had a grab on rotation when applying brakes. As an example, it feels as if you have a warped rotor. Upon measuring the rotor edge runout, we find a 25+/- thousandths difference. Quite a bit when 2 thou is acceptable. The rotor is true, discount that idea. Thinking the hub was bad, I've turned the rotor mounting face to be square to the spline shaft. (With this set of brakes, the rotors bolt onto the back of the hub.) That didn't fix the problem. And I have rotated the rotor on the hub each 72 degree option and still no luck. Here's the dilemma; What I have discovered is that when I install the hub and only snug the castle nut, I get a 5 thou runout. Not bad. As I tighten the castle nut, the runout increases to the 25 +/- thou. The position of the max runout is ALWAYS at 2 o'clock / 8 o'clock no matter which way you install the hub and rotor. Turn hub 90 degrees, max runout in same location. Do I have a worn spacer, bad bearings or does anyone know the magic of the IRS rear assy that I can't figure out? Any thoughts?
craig
