I have the JCW front brake calipers on my R53 MINI. I recently changed my brake pads getting ready for a track day next week and have noticed since the swap that the right caliper isn't sweeping the entire disk on the passenger side. (I can see the rust on the disk after it rains overnight isn't being swept clean.) The car is braking in a straight line, but the right side is about 100 degrees hotter than the left after my hour long commute in the morning. When I changed the pads, I pressed the pistons back into the caliper on both sides. And the passenger side piston appears to be retracting as the there is some movement of the caliper on the carrier and the rotor spins as freely as the otherside. Any thoughts?

 

obviously the pads and rotor aren't fully seated to each other. Either the rotor or pads aren't flat.

I have a feeling that it would self correct after a good while when the pads wear to fit the rotor. Maybe not the best situation though.