Brake shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.
REMOVAL & INSTALLATION
Servo Type With Single Anchor
See Figures 1 through 11
- Raise and support the vehicle.
- Remove the rear wheel, drum retaining clips and the brake drum.
- Remove the brake shoe return springs, noting how the secondary spring overlaps the primary spring.
- Remove the brake shoe retainer, springs and nails.
- Disconnect the automatic adjuster cable from the anchor and unhook it from the lever. Remove the cable, cable guide, and anchor plate.
- Remove the spring and lever from the shoe web.
- Spread the anchor ends of the primary and secondary shoes and remove the parking brake spring and strut.
- Disconnect the parking brake cable and remove the brake assembly.
- Remove the primary and secondary brake shoe assemblies and the star adjuster as an assembly. Block the wheel cylinders to retain the pistons.
- Measure the drum as described in this section.
- Apply a thin coat of lubricant to the support platforms.
- Attach the parking brake lever to the back side of the secondary shoe.
- Place the primary and secondary shoes in their relative positions on a workbench.
- Lubricate the adjuster screw threads. Install it between the primary and secondary shoes with the star wheel next to the secondary shoe. The star wheels are stamped with an L (left) and R (right).
- Overlap the ends of the primary and second brake shoes and install the adjusting spring and lever at the anchor end.
- Hold the shoes in position and install the parking brake cable into the lever.
- Install the parking brake strut and spring between the parking brake lever and primary shoe.
- Place the brake shoes on the support and install the retainer nails and springs.
- Install the anchor pin plate.
- Install the eye of the adjusting cable over the anchor pin and install the return spring between the anchor pin and primary shoe.
- Install the cable guide in the secondary shoe and install the secondary return spring. Be sure that the primary spring overlaps the secondary spring.
- Position the adjusting cable in the groove of the cable guide and engage the hook of the cable in the adjusting lever.
- Install the brake drum and retaining clips. Install the wheel and tire.
- Adjust the brakes and road test the truck.
Bendix Duo-Servo type
See Figures 12, 13 and 14
- Unhook and remove the adjusting lever return spring.
- Remove the lever from the lever pivot pin.
- Unhook the adjuster lever from the adjuster cable.
- Unhook the upper shoe-to-shoe spring.
- Unhook and remove the shoe hold-down springs.
- Disconnect the parking brake cable from the parking brake lever.
- Remove the shoes with the lower shoe-to-shoe spring and star wheel as an assembly.
- The pivot screw and adjusting nut on the left side have left-hand threads and right hand threads on the right side.
- Lubricate and assemble the star wheel assembly. Lubricate the guide pads on the support plates.
- Assemble the star wheel, lower shoe-to-shoe spring, and the primary and secondary shoes. Position this assembly on the support plate.
- Install and hook the hold-down springs.
- Install the upper shoe-to-shoe spring.
- Install the cable and retaining clip.
- Position the adjuster lever return spring on the pivot (green springs on left brakes and red springs on right brakes).
- Install the adjuster lever. Route the adjuster cable and connect it to the adjuster.
- Install the brake drum and adjust the brakes.