What is the best way to compress the rear caliper brakes, I am thinking a C clamp to force it shut, but before I do that, what is the proper way that anybody may know? I already have my brakes apart.

 

theres a special caliper tool to do this but it can also be done with just a pair of needle nose pliers. there are 2 little indents in the piston, just put the points of the pliers in there, push, and twist clockwise