Okay just put these on today and the castle nut goes to far in for the cotter pin to engage the nut correctly, it actually barely captures the nut. I tried backing the nut off to have the cotter pin sit perfect but I can move the rotor back and forth to much. Can I add a washer to space the nut out or is something wrong. My other question is the centering of the caliper in relation to the rotor, wilwood supplies shims but what are the chances that I dont need to use them. The rotors seem centered to my eyes ? I know the shims go between the mount and caliper but does a flat washer or lock washer go behind the bolts.