OTC Tools OTC 7317A Disc Brake Caliper Tool Kit. This tool is a “must” item when installing new brake pads on vehicles with 4-wheel disc brakes. Rotate the tool on the parking brake actuator to retract the piston. Works on most GM vehicles with 1-1/2″ brake pistons, most Ford vehicles, Pontiac Fiero, and import vehicles. Includes plate, 3/8″ extension, forcing screw, and adapters.