Disc Brake Caliper - Rear (Mark VII): Inspection

Clean all metal parts with isopropyl alcohol. Use clean dry compressed air to clean out and dry grooves and passages. Ensure caliper bore and component parts are free of any foreign material.
Inspect caliper bores for damage. Thrust screw bore must be smooth and free of pits. If piston is pitted, scored or chrome plating is worn off, replace piston adjuster assembly.
The adjuster can must be bottomed in piston to be properly seated and provide consistent brake function. If adjuster can is loose in piston, appears high in piston, is damaged or if brake adjustment is regularly too tight, too loose, or non-functioning, replace piston adjuster assembly.
NOTE: Do not attempt to service adjuster at anytime. When service is necessary, replace piston adjuster assembly.
Check adjuster operation by first assembling thrust screw into piston adjuster assembly, pulling 2 pieces apart by hand approximately 1/4" (6.35 mm), and then releasing them.
When pulling apart piston adjuster assembly and thrust screw, brass drive ring must remain stationary causing nut to rotate. When releasing piston adjuster assembly and thrust screw, nut must remain stationary with brass drive ring rotating. If components do not function properly, replace piston adjuster assembly.
Inspect all parts for damage and replace if necessary. Lightly sand or wire brush any rust or corrosion from caliper housing insulator bores.