Brake Shoe Replacement
Brake shoe linings are made from different heat resistant materials mixed with compounds such as brass, ceramic, and graphite materials. The lining can be either riveted or glued to the shoe. These materials have replaced the asbestos linings manufactured in the past. Please note that asbestos is a hazardous material. NEVER breath brake dust. Assume that every brake system you are working with is hazardous (It is!) and dispose of any brake dust properly.
When the brakes are applied the primary shoe is forced into contact with the brake drum by the piston of the wheel cylinder. The rotating brake drum then drags the primary brake shoe along with it in its forward rotation. This forward motion wedges the shoe into the drum and transfers to the secondary shoe which is also forced into the drum with help from the wheel cylinders piston. Brake shoe anchors are attached to the backing plate and allow for the brake shoes to come into full contact with the drum while providing an anchor for the momentum.
It is the lining of the primary and secondary shoes coming into contact with the rotating drum that causes the friction necessary to bring the vehicle to a stop. This friction is transformed energy and produces great heat. In fact a brake shoe can easily reach 450° F from a 55 MPH stop. As brake shoe temperatures increase the overall performance and effectiveness of the shoes will suffer. They also wear faster. The primary and secondary linings are often made from different materials and it is important not to mix up the two. Notice where the lining is fastened to the shoe before installing. The primary shoe faces the front of the vehicle and usually has a shorter lining and the secondary faces the rear.
