QUOTE(davep @ Oct 4 2021, 10:53 AM)
Often, when the rotors wobble (also called run-out) there are several factors to consider. If the rotors are old, then warping or uneven wear can be the culprit. Resurfacing the rotors can be done, but turning them on a brake lathe often results in reducing thickness below minimums. Disc-brake grinding was developed by a friend of mine, and Bear Alignment & Brake purchased his design. I remember working in a Honda shop 30 years ago this method was used on new rotors upon installation.
With new and used rotors I have found it best to sand the face and edges of the hub and the inside of the rotor where they mate. ANY surface high spot here will not allow the rotor to spin true. Once cleaned up, spin the rotor on the hub just like lapping a valve. To check the run-out you must have the rotor clamped to the hub just as if the wheel was torqued in place. Mark the high spots. Then index the rotor by one bolt hole, and do it again again and again until all positions have been tried. Figure out the orientation with the minimum run-out. If the run-out is more than the venting clearance, then you might have a problem.
Thank you I will go through this process first then adjust the clearance. much appreciated