If you’ve noticed that your car is having trouble maintaining its speed and one of your back wheels tends to get very hot after a drive, the problem may be a seized rear brake caliper. This can be dangerous if not fixed as quickly as possible; luckily, a caliper rebuild is a project that you can do yourself.
Remove the tire over the problematic caliper after jacking up the car and blocking the remaining tires. Strip all pads, springs, shims and pins from the caliper, as well as the outer dust seal.
Place a block of wood approximately the same thickness as two brake pads between the caliper and the piston. Cover the caliper with a shop towel to protect yourself from any fluids or debris, then carefully add compressed air to the caliper via the brake line inlet port. This will cause the piston to pop out.
Clean the piston with a shop towel and inspect it for any rust spots or other defects. Any minor blemishes can be buffed out with moistened 2,000-grit sandpaper; deep gouges or pits will require you to find a replacement piston.
Use your fingers or a soft pick to carefully remove the old piston seal from its groove and discard it. Clean the surface of the caliper bore with wet 600-grit sandpaper, then use hot, soapy water to wash off all dirt and debris from the caliper. Dry the caliper thoroughly after cleaning.
Install a new piston seal, then lubricate the piston with clean brake fluid and slide it halfway into the caliper. Use a screwdriver to push a new dust seal into its groove on the caliper and then push the piston in the rest of the way.
Put the caliper back into its casing on the wheel and tightly secure all bolts and screws, then put the tire back on. Repeat the process on the opposite side; all brake maintenance should be done on both sides of an axle at one time. When both calipers on an axle have been rebuilt and put back together, top off your car’s brake fluid and bleed the system. Be sure to thoroughly check for problems before taking the car out on the road after performing a brake repair.
