Drum Brake System: Testing and Inspection

BRAKE LININGS & SPRINGS

Inspect brake linings for excessive wear, damage, oil, grease or brake fluid contamination. If any of the above conditions exists, brake linings should be replaced. Do not attempt to replace only one set of brake shoes. They should be replaced as an axle set only to maintain equal braking forces. Examine brake shoe webbing, hold-down and return springs for signs of overheating indicated by a slight blue color. If any component exhibits overheating signs, replace hold-down and return springs with new ones. Overheated springs lose their pull and could cause brake linings to wear out prematurely. Inspect all springs for sags, bends and external damage and replace as necessary.
Inspect hold-down retainers and pins for bends, rust and corrosion. If any of the above is found, replace as required.

BACKING PLATE

Inspect backing plate shoe contact surface for grooves that may restrict shoe movement and cannot be removed by lightly sanding with emery cloth or other suitable abrasive. If backing plate exhibits above condition, it should be replaced. Also inspect for signs of cracks, warpage and excessive rust, indicating need for replacement.

ADJUSTER MECHANISM

Inspect all components for rust, corrosion, bends and fatigue. Replace as necessary. On adjuster mechanism equipped with adjuster cable, inspect cable for kinks, fraying or elongation of eyelet and replace as necessary.