Drum Brake System: Service and Repair

REAR DRUM BRAKES

TOOLS REQUIRED
^ J21177-A Brake Shoe Setting Gauge

DISASSEMBLY
1. Release park brake.

CAUTION: MAKE SURE VEHICLE IS PROPERLY SUPPORTED AND SQUARELY POSITIONED ON THE HOIST. TO HELP AVOID PERSONAL INJURY WHEN A VEHICLE IS ON A HOIST, PROVIDE ADDITIONAL SUPPORT FOR THE VEHICLE ON THE OPPOSITE END FROM WHICH COMPONENTS ARE BEING REMOVED.

2. Raise vehicle on hoist.
3. Remove rear wheel and tire assembly.





4. Remove brake drum retaining screw.

NOTICE: Do not pry against brake backing plate. This will bend plate.

IMPORTANT: If difficulty is encountered removing drum, the following steps apply.





5. Remove rear drum.
5.1 Insert a screwdriver in access hole and push park brake lever toward outside of drum to release shoes from adjuster.
5.2 Remove brake drum.

NOTICE: Do not over extend spring. Over extending spring will weaken it.

6. Remove upper return spring.





7. Remove upper return spring retaining bracket.
8. Detach adjuster lever and spring.





9. Pull brake shoes apart slightly and remove adjuster unit.





10. Remove brake shoe hold down springs and pins.





11. Remove leading (front) brake shoe and trailing (rear) brake shoe from park brake cable.





12. Disassemble brake adjuster components: adjusting socket, screw, clip, and nut.
13. Clean adjusting socket, screw, and nut in clean denatured alcohol.
14. Inspect adjuster assembly, making sure that adjuster screw threads smoothly into adjusting nut, over full threaded length.

NOTICE: If wheel cylinder is found to be damaged, replace it. Do not attempt to repair wheel cylinder.

15. Inspect wheel cylinder for leakage, cuts or damaged boots. Also, make sure that wheel cylinder is not seized.

ASSEMBLY

IMPORTANT: When replacing rear brake shoes, inspect backing plate for excessive wear at six raised shoe contact pads. Excessive wear at raised shoe contact pads, such as notches or deep grooves, could impede shoe travel.

IMPORTANT: Never replace brake pads on one side of axle only. Left and right side brake pads must be replaced only as axle sets.





1. Lubricate the following components:
^ Adjuster lever surfaces that rub on brake shoe web.
^ Backing plate at the six raised shoe contact pads.

2. Install park brake cable to park brake lever of trailing (rear) brake shoe.





3. Install trailing (rear) brake shoe to backing plate using hold down pin and retaining spring.





4. Attach lower retaining spring and install leading (front) brake shoe, hold down pin, and retaining spring.





5. Slightly pull apart brake shoes and install adjuster unit.
6. Install adjuster lever with spring.

NOTICE: Check that brake shoe is correctly engaged in wheel cylinder at top and anchor at bottom.

NOTICE: Check that adjuster notches properly engage in brake shoe notches.





7. Install retaining bracket and install upper return spring.





8. Using a 165 - 368 mm (6.5 - 14.5 inch) caliper such as Brake Shoe Setting Gauge J21177-A (or equivalent), measure inside diameter of brake drum.





REAR DRUM DIAMETER

IMPORTANT: Refer to "Inspecting and Refinishing Brake Drums". Service and Repair





9. Measure outside diameter of brake shoes and adjust brake adjuster to obtain 0.50 mm (.020 inch) less than the reading obtained in previous step.
10. Install brake drum and retaining screw.
Torque:
Brake Drum Retaining Fastener: 4 Nm (35 inch lbs.)

11. Bleed brakes if new wheel cylinder or backing plate was installed.

NOTICE: Before installing wheels, remove rust or corrosion from wheel mounting surfaces and brake rotors. Failure to do so can cause wheel bolts to loosen in service.

12. Position wheel and tire assembly onto hub.
13. Install wheel bolts and tighten in a crisscross pattern.
13.1 Hand tighten all five wheel bolts.
13.2 Use a torque wrench to tighten wheel bolts using a crisscross pattern.
Torque:
Wheel Bolts (Initial Torque): 63 Nm (46 ft. lbs.)
13.3 Use a torque wrench to final tighten wheel bolts using a crisscross pattern.
Torque:
Wheel Bolts (Final Torque): 125 Nm (92 ft. lbs.)
14. Lower vehicle from hoist.

CAUTION: IF THIS OPERATION IS NOT CARRIED OUT, BRAKES WILL NOT OPERATE PROPERLY DURING INITIAL BRAKE APPLICATIONS.

15. Apply and release brake pedal 20 times to allow adjuster to position brake shoes.
16. Adjust park brake cable.