jack up veh. support with stands,remove wheels,remove two 13mm bolts holding caliper onto bridge holding pads,there is a tool for winding these pistons into the caliper but sometimes you get away with a good set of long nose pliers into the two indents in the piston,try pressing in and turning,may be a bit tight to get moving but persevere,some motors are wound in a/clockwise some clockwise,assemble with copaslip on all mating surfaces and make sure the lever that connects to your h/brake cable to the caliper returns all the way to its stop when the h/brake is off,good luck
wickham
July 2010