- Brake linings that are worn to within 1/32 inch (0.79 mm) of a rivet head or that have been contaminated with brake fluid, grease, or oil must be replaced.
Potential brake shoe problems. Courtesy of Wagner Brake Products.
- Failure to replace worn linings results in a scored drum. When it is necessary to replace brake shoes, they must also be replaced on the wheel on the opposite side of the vehicle. Inspect brake shoes for distortion, cracks, or looseness. If these conditions exist, the shoe must be discarded.
- Do not let brake fluid, oil, or grease touch the brake lining.
- If a brake lining kit is used to replace the linings, follow the instructions in the kit and install all the parts provided.
- The two general methods of attaching the linings to the brake shoes are bonding and riveting.
- The bonded linings are fastened with a special adhesive to the shoe, clamped in place, then cured in an oven. Instead of using an adhesive, some linings are riveted to the shoe.
- Riveted linings allow for better heat transfer than bonded linings.
Drum Shoe and Brake Installation
- Before installing the shoes, be sure to sand or stone the inner edge of the shoe to dress down any slight lining or metal nicks and burrs that could interfere with the sliding upon the support pads.
- A support (backing) plate must be tight on its mount and not bent. Stone the shoe support pads brightly and dress down any burrs or grooves that could cause the shoes to bind or hang up.
- Using an approved lubricant, lightly coat the support pads and the threads of servo star wheel adjusters. On rear axle parking brakes, lubricate any point of potential binding in the linkage and the cable. Do not lubricate nonservo brake adjusters other than to free a frozen adjuster with penetrating oil.
The areas or pads where the brake show will rub or contact the backing plate.
- Reassemble the brakes in the reverse order of disassembly. Make sure all parts are in their proper locations and that both brake shoes are properly positioned in either end of the adjuster.
- Also, both brake shoes should correctly engage the wheel cylinder pushrods and parking brake links.
- They should be centered on the backing plate. Parking brake links and levers should be in place on the rear brakes.
- With all of the parts in place, replace the brake drum.