- Verify that the parking brake lever is in the fully released position.
- Raise and safely support the vehicle.
Perform the following steps on each rear drum brake assembly:
- Remove the tire and wheel assembly from the vehicle.
- Remove the brake drum. Refer to Brake Drum, removal & installation.
Using a brake shoe gauge, Special Tool C-3919 or equivalent, measure the inside diameter of the brake drum.
Place the other side of the brake shoe gauge on the brake shoes as shown.
- Adjust the shoe diameter to the setting on the gauge. To adjust the shoe diameter, turn the adjuster-screw star-wheel using a screwdriver inserted through the adjusting hole in the rear of the shoe support plate. Once the tip of the screwdriver contacts the star-wheel teeth, move the handle of tool downward using the support plate as a pivot to adjust the shoes outward.
- Once the shoe diameter is set, reinstall the brake drum.
- Turn the drum. A slight drag should be felt while rotating the drum.
- Install the tire and wheel assembly. Tighten the wheel mounting nuts to 100 ft. lbs. (136 Nm).
- After adjusting both rear drum brakes, lower the vehicle.
- Apply and release the parking brake lever one time after the adjustment process is completed so the parking brakes can readjust themselves to the new brake shoe adjustment.
- Road test the vehicle stopping in both forward and reverse directions. The automatic adjuster will continue to adjust the brakes as necessary during the road test.
Removal & Installation
- Before servicing the vehicle, refer to the Precautions Section.
- Remove the rear wheel assembly.
- Locate and remove the rubber plug from the top of the brake support plate (backing plate).
- Insert a brake adjuster tool or similarly shaped pry tool through the automatic adjuster access hole and engage the teeth on the adjuster quadrant. Then rotate the quadrant so the teeth of the quadrant are moved toward the front of the vehicle. This will back off the adjustment of the rear brake shoes.
- Continue moving the quadrant toward the front of the vehicle until it stops moving.
- Remove the drum from the hub assembly.
- Remove the actuating spring from the adjuster mechanism and the trailing brake shoe.
- Remove the upper return spring from the brake shoes.
- Remove the lower return spring from the brake shoes.
- Remove the brake shoe retainer and the pin attaching the leading brake shoe assembly to the brake support plate.
- Remove the leading brake shoe and the adjuster mechanism as an assembly from the rear brake support plate. The adjuster mechanism cannot be separated from the leading brake shoe until the brake shoe and the adjuster mechanism is removed from the support plate.
Remove the trailing brake shoe retainer and pin attaching the trailing brake shoe assembly to the brake support plate. Remove the trailing brake shoe assembly.
NOTEOn this vehicle, the parking brake actuating lever is permanently attached to the trailing brake shoe assembly. Do not attempt to remove it from the original brake shoe assembly or reuse the original actuating lever on a replacement brake shoe assembly. All replacement brake shoe assemblies for this vehicle must have the actuating lever as part of the trailing brake shoe assembly.
- Remove the parking brake cable from the parking brake lever. Do not remove the lever from the brake shoe.
Remove the automatic adjuster mechanism from the brake shoe by fully extending the adjuster. Rotate the adjuster out to release it from the brake shoe.
- Thoroughly clean all the 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 the quadrant (toothed part) of the adjuster is free to rotate throughout its entire tooth contact range and is free to slide the full length of its mounting slot. Check the knurled pin. It should be securely attached to the adjuster mechanism and its teeth should be in good condition. If the adjuster is worn or damaged, replace it. If the adjuster is serviceable, lubricate if lightly with high-temperature grease between the strut and the quadrant. Check the brake springs. Overheating indications are paint discoloration or distorted end coils. Replace parts as required.
- Inspect the brake drums for cracks or signs of overheating. Measure the drum run-out and diameter. If it is not to specification, reface the drum. Run-out should not exceed 0.006 inch (0.15mm). The diameter variation (oval shape) of the drum braking surface must not exceed either 0.0025 inch (0.064mm) in 30° rotation, or 0.0035 inch (0.089mm) in 360° rotation. All brake drums are marked with the maximum allowable brake drum diameter on the face of the drum.
Lubricate the 8 brake shoe contact points with high-temperature grease.
NOTEThe trailing brake shoe assemblies used on the rear brakes of this vehicle are unique to the left and right side of the vehicle. Care must be taken to ensure the brake shoes are properly installed in their correct side of the vehicle. When the trailing shoes are properly installed on their correct side of the vehicle, the parking brake actuating lever will be positioned under the brake shoe web.
- Install the parking brake cable onto the parking brake lever and install the trailing brake shoe and attaching pin.
- Install the automatic self-adjuster on the leading brake shoe by rotating it inward to attach. Install the leading shoe and adjuster assembly to the brake support plate.
- Make sure the leading brake shoe is squarely seated on the brake support plate shoe contact areas, and install the brake retainer on the retainer pin.
Install the lower return spring.
NOTEThe upper brake shoe return spring and adjuster mechanism actuating spring are unique to the side of the vehicle they are used on. The springs are colored for identification. The left side springs are green and the right side springs are blue.
- Install the upper return spring (blue, right side; green, left side) on the leading brake shoe first, then on the trailing brake shoe.
- Install the self-adjuster spring on the trailing brake shoe first then attach it to the adjuster.
- Install the rear brake drums.
- Install the wheel and tire. Torque the lug nuts in a star pattern sequence to about 45 ft. lbs. (61 Nm), then repeat the pattern and final torque to 100 ft. lbs. (136 Nm).
- Adjust the rear brakes by depressing the brake pedal. Brake shoe adjustment will occur the first time the brake pedal is depressed, pushing the rear brake shoes against the braking surface of the rear brake drums. Brake shoes should now be correctly adjusted and will not require any type of manual adjustment.
- Road test the vehicle to check for the proper brake operation.