Retracting the brake piston back into the cylinder is an important task in disc brake servicing. On many rear disc brake designs, this task is accomplished in the same manner as on the front brakes; the piston is simply pushed back into the cylinder. On other designs, however, the piston must be simultaneously pushed and rotated back into the cylinder. A brake reset tool is a special brake tool that is used to perform this task. Each auto manufacturer has a different brake design, and each produces a specific reset tool suitable for its own design. Aftermarket brake reset tool kits are also available that have a set of adapters that allow them to work on most different designs.
Instructions
- 1
Park the vehicle on a firm and level surface. Do not set the parking brake. Securely block the front wheels to prevent accidental vehicle movement. Partially loosen the lug nuts of the rear wheel to be serviced, and jack the car up. Support the car securely on a jack stand. Completely remove the lug nuts, and pull the wheel off.
2Remove the two caliper bolts. Lift the caliper up and off the disc. Hang the caliper out of the way using a bungee cord, taking care not to damage the flexible brake hose.
3Remove the brake pads from the caliper by sliding them in toward the middle of the caliper until they release. If retaining clips are present, pry them off the caliper bracket with a screwdriver or pull them off with pliers. Do not damage the clips during removal so that they can be reused during reassembly.
4Retract the piston using the brake reset tool. The tool consists of a threaded spindle that passes through a metal plate. The spindle has a handle on one end and a keyed face on the other end. Place the keyed face against the piston face, and match the protrusions of the tool face to the indentations in the piston face. Depending on the design, the tool may have pins or ridges that insert into holes or grooves on the piston face. Place the metal plate of the tool against the inner surface of the outer caliper frame. Rotate the tool handle to advance the spindle while simultaneously rotating the piston. Continue until the piston is fully retracted into the cylinder. Take care not to damage the rubber piston boot. When using an aftermarket tool, you must first fit the adapter that corresponds to your specific piston face before using the tool.
