Problem: Rear drum brake comebacks
Cause: Not following the proper steps to ensure a quality rear drum brake job
Solution: When performing rear drum brakes follow the necessary steps to ensure a quality job and no comebacks. Here are the steps to a quality rear brake job:
1. If new to the drum brake type being service only work on one side at a time and lay the parts out as they came off.
2. If the vehicle is used to tow a boat and is constantly submersed in water you can waterproof the wheel cylinders by applying a coat of silicone to the dust boots as shown in Figure 67.1. Make sure there is a film on the boot to housing sealing surface and the pushrod sealing surface.
Figure 67.13. Clean the backing plate shoe lands. Inspect the shoe lands for excessive wear that would alter the shoe’s position on the backing plate. If shoe lands are worn as shown backing plate replacement or repair will have to be performed.
4. Clean only the surfaces that influence the operation of the drum brake system. Do not perform cosmetic cleaning.
5. Lube all metal to metal contact points with a high quality molylube. Apply only a light film (See Figure 67.2)
Figure 67.26. Before installing the new friction material either wash your hands to prevent contaminating the new friction material or do what is shown in Figure 67.3. The masking tape protects the brake shoes during the installation process and can be easily removed once done.
Figure 67.37. Rough in the adjustment
8. On duo-servo drum brakes (adjuster at bottom) make sure parking brake is fully released by checking strut rod clearance with primary shoe. There should be a small gap between strut rod and primary shoe of approximately 1/8". You should be able to push the strut rod against the anti-rattle spring.
9. Make sure to clean drum's friction surface before installing. if the drums were machined there will be a layer of fine metal dust on the friction surface and new drums are treated with a rust preventative.
