How to Fit Rear Brake Discs

Rear disc brake service procedures can be complicated due to the rear brakes being incorporated in the emergency brake mechanism. This mechanism takes the form of a dedicated disc brake within the disc casting on some models, while other models have a mechanical emergency brake mechanism built in to the brake caliper. It is important to understand the different types of rear disc brake configurations, and to be able to adjust the service procedure to suit the particular model being worked on.

• 1

  Park the vehicle on a level surface. Put an automatic transmission in park, or put a manual transmission in first or reverse gear. Do not set the parking brake. Securely block the front wheels to prevent the vehicle from rolling. Loosen the lug nuts one full turn. Jack the vehicle, and support it securely on a safety stand. Completely remove the lug nuts, and pull the wheel off.

• 2

  Remove the two caliper bolts. Some models have rubber caps over the caliper bolt heads. If these are present, pry or pull them off. Grip the caliper, and rock it back and forth a few times to spread the brake pads slightly. Lift the caliper off the disc, and hang it out of the way on a wire hook or a bungee cord. Do not kink, or stretch, the flexible brake hose.

• 3

  Pry, or pull, off any retaining clips that hold the brake pads in the caliper. Avoid damaging the clips, so they can be reused. Slide the brake pads and shims out of the caliper.

• 4

  Push the caliper piston into the cylinder with a brake piston retractor. Place the swivel on the end of the retractor spindle on the piston face, and place the metal plate of the retractor against the inner surface of the outer caliper frame. Turn the retractor spindle clockwise to advance the spindle, and force the piston into the cylinder bore. Do not pinch the rubber boot seal between the piston and cylinder.

• 5

  Pull the disc off the hub. Some discs have retaining bolts or screws, which must be removed. On other models, there is a central hub nut that must be removed before removing the disc. If the disc is difficult to remove, the parking brake may be set. If the disc is seized to the hub, firmly tap the center area of the disc with a mallet to loosen it. Do not hit the disc outer rim or the braking surface area.

• 6

  Measure the brake pad lining thickness with a finely graduated ruler. If it is less than the manufacturer-recommended minimum lining thickness, or if the linings are damaged or unevenly worn, replace the pads. The minimum recommended lining thickness can be found in the manufacturer shop manual or the aftermarket equivalent repair manual. Most auto parts store employees can answer your questions, as well.

• 7

  Measure the disc thickness with a brake-disc micrometer at several places around the disc, and compare it against the manufacturer-recommended minimum thickness, as stated in the shop manual. If a shop manual is not available, check the outer rim of the disc, as the minimum allowable thickness is often stamped into the metal of the outer disc rim. Replace the disc if the measured thickness is below the specified minimum, or if it is deeply scored, warped or cracked. Any minor disc damage can be repaired by having the disc machined at a brake shop or auto parts store.

• 8

  Reassemble the brake by following the steps in reverse order. Coat the caliper bolts with brake grease before reinserting them into the caliper mounts. Start the vehicle, and test the brake operation. Replace the wheel, and lower the vehicle.