How to Rebuild & Repair Motorcycle Rear Brake Calipers

Disc brakes afford advantages over drum brakes on the rear wheel of a motorcycle. The brake surface is greater on a disc, or rotor, and heat dissipates faster. Overheating can lead to a compounding reduction of stopping power, known as “brake fade.” Moisture introduced into a brake drum diminishes performance, while disc brakes benefit from wet conditions by cooling quicker. Disc brake calipers are simple structures, but they may be adversely affected by minor discrepancies.


1) Remove the rear caliper from the bike following manufacturer’s recommended procedure. Remove the caliper bleed screw and drain all fluid. Discard fluid according to local regulations or laws. Examine the bleed screw thread bore of the caliper. Replace any caliper that exhibits damaged or missing screw bore threads.

2) Remove the brake pads and any attaching hardware. Remove the piston from the caliper by directing a short burst of compressed air into the bleed screw bore. Continue removal of the piston by hand once it emerges past the dust boot. Remove the dust boot from the caliper.

3) Remove the rubber seal ring from the piston. Examine the piston exterior surface and cylinder bore. Replace any parts that show heavy rust, pitting or scoring. Remove minor defects in the cylinder bore with the proper size and grit bore hone. Clean all parts with denatured alcohol.

4) Remove and replace all rubber parts left in the caliper. Lubricate any guide bushings or boots with a light coat of silicone-based brake lube. Install a new seal ring on the piston and lightly lubricate the entire piston with brake fluid specified for use with your model motorcycle.

5) Install a new dust boot into the cylinder bore and ensure that it is seated. Place a brake pad over the boot and drive it in evenly using a C-clamp. Ensure the boot is completely seated. Position the piston over the center of the dust boot. Apply light air pressure to the bleed screw bore while pressing the piston past the inflated boot.

6) Ensure the piston is fully seated. Install the bleed screw and brake pads into the caliper. Replace the caliper on the bike by reversing the removal procedure. Bleed the caliper according to manufacturer’s recommendations.

Extra Tips:

* Use an air nozzle that allows precise control for piston installation. Distracting noises from the dust boot are common during this procedure.

* Use protective eyewear when using compressed air to safeguard against injury. Never re-use brake fluid or sealing washers on brake hose fittings.

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