When replacing the pads on the rear brakes of a 2003 Mini Cooper, I could not compress the piston into the caliper. I turned the piston counter clockwise a number of turns and it came off. It was then that I realized that it had been on a threaded rod (for the park brake). When I installed the piston back into the caliper, it compressed all the way back in without having to be threaded.

I carried on and replaced the pads, bled the system and everything seems to work just fine (parking brake included).

I realize that the system is designed for the parking brake to adjust itself as the pads wear. My question is, by removing the piston, and then simply pushing it back in, does the piston become threaded on the rod once again and the system work as it was designed, or will it no longer work as it was designed to???

Thanks so much