How to Change Rear Disc Brakes Without A Brake Piston Wrench

Disc braking technology has supplanted the drum brake as the dominant type of brake used on automobiles, and with good reason. Disc brakes perform better, and the simplicity of disc brake design makes them easier to service as well. On the rear brakes, however, there remains the problem of how to incorporate the emergency brake system, and this problem has been addressed in different ways. Some models incorporate a dedicated drum brake mechanism. Others employ a mechanism in the disc brake piston, and this brings additional complications when retracting the piston during servicing. With a little ingenuity, however, this task can be accomplished without the use of expensive special tools.

Instructions

1

Park the vehicle on a firm and level surface. Put automatic transmissions in the "park" setting and put manual transmissions in either first or reverse gear. Leave the parking brake off. Securely block the front wheels to prevent accidental vehicle rolling. Loosen the lug nuts of the rear wheel to be serviced about one full turn each and jack the car up. Support the car securely on an axle stand. Completely remove the lug nuts and pull the wheel off.

2

Remove the two caliper retaining bolts. Grip the caliper and rock it back and forth a few times to spread the brake pads slightly and then lift the caliper up and off the disk. Hang the caliper out of the way using a wire or bungee cord, taking care not to stretch or kink the flexible brake hose.

3

Slide the brake pads out of the caliper. If retaining clips are present, these can be pried off the caliper bracket with a screw driver or pulled off with pliers. Take care not to damage clips during removal so that they can be reused during reassembly.

4

Screw the piston back into the cylinder. First place the spindle swivel of a large "C" clamp on the face of the piston and hook the frame end of the clamp on the back of the caliper. Tighten the clamp to put firm pressure on the piston, but do not attempt to force the piston back into the cylinder. Grip the outside of the protruding piston with channel lock pliers and rotate the piston clockwise to screw it back into the cylinder. Be careful not to pinch or damage the rubber piston seal. Retighten the C-clamp after every rotation of the piston in order to keep firm pressure on the piston face. Continue rotating the piston in this manner until you can no longer get a good grip on the piston with the channel lock pliers.

5

Measure the thickness of the brake pad linings with a finely graduated ruler. Replace the pads of the lining thickness is less than the manufacturer's specified minimum, or if the linings are damaged or unevenly worn. Measure the thickness of the brake disc about one half to three quarters of an inch from the rim, at eight points equally spaced around the disc. Replace the disc if the thickness is less than the manufacturer's specified minimum, or if the disc is cracked, deeply scored, glazed, or otherwise irreparably damaged. Minor damage can be repaired by having the disc machined at your local auto parts store.

6

Remove any retaining screws or bolts from the disc and pull the disc straight off the hub. If the disc is seized, tap the center part of the disc firmly with a hammer or mallet, taking care not to hit the braking surface or outer rim of the disc. Some discs have threaded holes near the center. Bolts can be threaded into these holes and tightened to jack a stubborn disc off the hub. Of course if the old disc is in good shape there is no need to remove it.

7

Clean all parts with brake cleaning fluid. Be sure to catch all used fluid in a catch pan and dispose of used fluid in accordance with local regulations. Install a new disc if needed, taking care to thoroughly clean the hub before installing the new disc. Liberally lubricate the caliper bolts with brake grease and then reassemble the caliper with new pads and shims if needed and reinstall the caliper. Reinstall the wheel and lower the car.

8

Repeat the procedure on the other rear wheel. Start the car and pump the brakes a few times to reset the pistons and parking brake adjusters. Test the brake operation before driving.