Turn the brake adjuster screw clockwise until the piston is loose enough to remove.
Remove the piston dust seal.
WARNING: USE ONLY AS MUCH COMPRESSED AIR AS NECESSARY TO REMOVE THE PISTON. EXCESSIVE PRESSURE CAN FORCE THE PISTON OUT OF THE CALIPER BORE WITH ENOUGH FORCE TO CAUSE PERSONAL INJURY. NEVER ATTEMPT TO CATCH THE PISTON BY HAND AS IT COMES OUT OF THE BORE.
CAUTION: Do not use a screw driver or any other similar tool to pry the piston out of the bore. Piston damage could result.
NOTE: When removing the piston it is necessary to cover the brake caliper bleeder screw hole and the brake adjuster screw hole.
NOTE: Do not hone the cylinder bore. Pistons are not available for honed cylinder bores. If the rear disc brake caliper bore is scored or corroded, replace the rear disc brake caliper.
Place a block of wood between the piston and the rear disc brake caliper and remove the piston using compressed air.
Remove the snap ring, rear disc brake adjuster spindle, the O-ring, and the brake connecting link. Discard the O-ring.
CAUTION: Use a plastic or wooden pick to remove the piston seal from the rear disc brake caliper bore. A metal tool may scratch or nick the piston seal groove which could result in a leak.
Remove the piston seal from the bore, and discard the seal.
Remove the rear brake operating lever spring.
Remove the rear brake operating lever.
Remove the rear brake operating lever seal.
Assembly
CAUTION: When assembling the rear disc brake caliper it is necessary to lubricate the piston and all the internal rubber components using High Performance DOT 3 Motor Vehicle Brake Fluid C6AZ-19542-AB or equivalent meeting Ford specification ESA-M6C25-A, DOT 3.