Press on the brake pedal a few times to use up the vacuum assistance, then I unbolt the calipers, and I suspend the caliper in a bucket (I raise the bucket on a few bricks so that the caliper can rest on it inside).
Then gently press the brake pedal a few times and at some point the caliper piston will pop out. Then undo the brake hose, inspect for cracks and take the caliper to your bench.
Clean it with brake cleaner, and make sure that the inside of the caliper where the piston lives is clean and free of any rust. Remove the o-ring from the old piston and slide on the new o-ring. Lube up the inside of the caliper with a little fresh fluid and slide in the piston. Fit all the new rubber seals, etc that come with the caliper kit, but remember to use lots of hi temp anti seize compound on the slider pins.
Refit the caliper to the hose, put back on car, refit pads and bleed the fluid. Repeat on other side
It's pretty easy to do, the tricky part is to get the piston out without squirting fluid everywhere.
