- Inspect the brake shoes for wear using a ruler or Vernier caliper. If the lining is thinner than specification or there is evidence of the lining being contaminated by brake fluid or oil, replace all brake shoe assemblies (a complete axle set).
- When replacing shoes, always check the surface of the drums for scoring or wear. The drums should be removed for resurfacing if badly scored.
The Brake Specifications chart in this section contains the manufacturer's specified shoe wear limit. However, this measurement may disagree with your state inspection laws. Always abide by your state inspection law specifications if they disagree with the manufacturer's specifications.
REMOVAL & INSTALLATION
See Figures 1, 2, 3, 4 and 5
- Raise the vehicle and remove the rear wheels.
- Release the parking brake.
- Remove the brake drum.
- Remove the return springs, adjuster assembly, hold-down springs, and brake shoes.
The brake shoes can be removed as an assembly by removing the hold-down springs and releasing the parking brake cable. This allows the brake shoe assembly to be disassembled off the vehicle.
- Disconnect the parking brake cable from the brake shoe.
- Clean the backing plate. A very thin film of lithium grease may be applied to the pivot points at the ends of the brake shoes. Grease the shoe locating buttons on the backing plate, also. Be careful not to get grease on the linings or drum.
- Inspect the wheel cylinder for leaks and replace as necessary.
- Inspect the brake drums, and machine or replace as necessary.
- Reconnect the parking brake cable.
- Hook the return springs into the new shoes. The return spring ends should be between the shoes and the backing plate. The longer return spring must be adjacent to the wheel cylinder.
- Install the adjuster assembly between the brake shoes. (Rotate the nut until the adjuster rod is at its shortest point.) Place one shoe in the adjuster and piston slots, then pry the other shoe into position. Install the hold-down springs and reconnect the return springs.
- Install the brake drums and wheels.
- Adjust the brakes.
- Bleed the hydraulic system, if necessary.
- Apply the parking brake and ensure that the brake shoes do not drag once the parking brake is released.
The drum brakes are self-adjusting and require a manual adjustment only after the brake shoes have been replaced, or when the length of the adjusting screw has been changed while performing some other service.
- Raise and support the vehicle safely.
- Remove the rubber plug from the adjusting slot on the backing plate.
- Insert a brake adjustment tool into the slot and engage the lowest possible tooth on the starwheel. Move the end of the brake spoon downward to move the starwheel upward and expand the adjusting screw. Repeat this operation until the brakes lock the wheels.
- Insert a small screwdriver or piece of firm wire (coat hanger wire) into the adjusting slot and push the automatic adjusting lever out and free of the starwheel on the adjusting screw, and hold it there.
- Engage the topmost tooth possible on the starwheel with the brake adjusting spoon. Move the end of the adjusting spoon upward to move the adjusting screw starwheel downward and contract the adjusting screw. Back off the adjusting screw starwheel until the wheel spins freely with a minimum of drag. Keep track of the number of turns that the starwheel is backed off, or the number of strokes taken with the brake adjusting spoon.
- Repeat this operation for the other side. When backing off the brakes on the other side, the starwheel adjuster must be backed off the same number of turns to prevent side-to-side brake pull.
- Install the wheel and tire assemblies, then lower the vehicle.
- When the brakes are adjusted, make several stops while backing the vehicle to equalize the brakes on both of the wheels.