See Figure 1
- Measure the combined thickness of the brake shoe rim and lining. The minimum leading brake shoe rim and lining thickness specification is 1 / 8 inch (3.0mm). The minimum trailing brake shoe rim and lining thickness specification is 7 / 64 inch (2.8mm).
- If any of the measurements fall below the minimum specifications, replace the brake shoes.
- Thoroughly clean all parts. The brake lining should show contact across the entire width and from heel to toe; otherwise, replace. Clean and inspect the brake support plate and the automatic adjuster mechanism. Be sure that the adjuster mechanism has full movement throughout it adjustment range and that its teeth should be in good condition. If the adjuster is worn or damaged, replace it. If the adjuster is serviceable, lubricate the moving parts with high-temperature grease. Check the brake springs. Overheating indications are paint discoloration or distorted end coils. Replace parts as required.
REMOVAL & INSTALLATION
See Figures 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16
- Raise and safely support the vehicle.
- Remove the rear wheels and the brake drums.
- Be sure the parking brake pedal is in the released position. Create slack in the rear parking brake cables by grasping an exposed section of the front parking brake cable, pulling it down and rearward. Maintain the slack in the brake cable by installing a pair of locking pliers onto the parking brake cable just rearward of only the rear body outrigger bracket.
- Remove the adjustment lever spring from the automatic adjustment lever and front brake shoe (leading brake shoe).
- Remove the automatic adjustment lever from the front brake shoe (leading brake shoe).
- Remove the brake shoe-to-brake shoe lower return spring.
- Remove the tension clip that secures the upper return spring to the automatic adjuster assembly.
- Remove the brake shoe-to-brake shoe upper return spring.
- Remove the rear brake shoe (trailing brake shoe) hold-down clip and pin.
- Remove the trailing brake shoe, parking brake actuating lever and parking brake actuating strut from the brake support plate.
- Remove the automatic adjuster assembly from the leading brake shoe.
- Remove the leading brake shoe hold-down clip and pin. Remove the leading brake shoe.
- Remove the parking brake actuator plate from the leading brake shoe and install onto the replacement brake shoe.
- Thoroughly clean and dry the backing plate. To prepare the backing plate, lubricate the 8 brake shoe contact areas and brake shoe anchor, using suitable grease.
- Install the leading brake shoe into position on the brake shoe support plate. Secure the leading brake shoe by installing the brake shoe hold-down clip and pin.
- Install the parking brake actuating strut onto the leading brake shoe and then install the parking brake actuating lever onto the strut.
- Lubricate the shaft threads of the automatic adjuster screw assembly with anti-seize lubricant. Install the automatic adjuster screw assembly onto the leading brake shoe.
- Install the trailing brake shoe onto the parking brake actuating lever and parking brake actuating strut.
- Place the trailing brake shoe into position on the brake support plate and install the brake shoe hold-down clip and pin.
- Install the brake shoe-to-brake shoe upper return spring.
- Install the tension clip that secures the upper return spring to the automatic adjuster assembly. Be sure the tension clip is positioned on the threaded area of the adjuster assembly or the function of the automatic adjuster will be affected.
- Install the brake shoe-to-brake shoe lower return spring.
- Install the automatic adjustment lever onto the leading brake shoe.
- Install the actuating spring onto the automatic adjustment lever and leading brake shoe. Check to be sure the automatic adjustment lever makes positive contact with the star wheel on the automatic adjuster assembly.
- Once the brake shoes and all other brake system components are fully and correctly installed, remove the locking pliers from the front parking brake cable. This will remove the slack and correctly adjust the parking brake cables.
- Make sure there is no grease on the brake shoe linings, then install the brake drums.
- Adjust the rear brakes, then lower the vehicle and check the brakes for proper operation.
- Install the wheel and lug nuts. Torque the lug nuts, in a star pattern sequence, to 95 ft. lbs. (129 Nm).
- Road test the vehicle. The automatic adjuster will continue to adjust the brake shoes during the road test.
See Figures 17 and 18
Normally, self-adjusting drum brakes will not require manual brake shoe adjustment. However, in the event of brake shoe replacement, it is advisable to make the initial adjustment manually to speed up the adjusting time.
- Raise and safely support the rear of the vehicle securely on jackstands.
- Disconnect the parking brake cable (for the wheel that is being serviced) from the parking brake cable equalizer. This step is necessary to gain access to the star wheel adjuster. If this is not done, the cable and spring inside of the brake drum will be in the way of the star wheel.
- Remove the rubber plug from the rear brake adjusting hole, in the back of the rear brake backing plate.
- Make sure that the parking brake lever is fully released.
- Insert Special Brake Adjusting Tool C-3784 or equivalent, into the adjusting hole on the backing plate and against the star wheel of the adjusting screw. Move the tool handle upward until a slight drag is felt when the vehicle's road wheel is turned.
- Insert a small (but strong) thin rod through the adjusting hole. Push the adjusting lever out of engagement with the star wheel. Be careful not to bend or distort the lever or spring. While holding the lever out of engagement, back off the star wheel just enough to ensure a free wheel with no brake shoe drag.
- Repeat this procedure on the other rear wheel.
- Install the rubber plug back into the adjusting hole.
- Connect the parking brake cable(s) to the equalizer.
- Lower the vehicle.
- Carefully road test the vehicle and check for proper brake system operation.