Drum Brake System: Testing and Inspection
INSPECTION1. Inspect disassembled parts.
Inspect the disassembled parts for wear, rust or damage.
2. Measure brake shoe lining thickness.
Fig. 4 Measuring Brake Shoe Lining Thickness:
Using a ruler, measure the shoe lining thickness.
Standard thickness: 6.0 mm (0.236 inch)
Minimum thickness: 1.0 mm (0.039 inch)
If the shoe lining is less than the minimum or shows signs of uneven wear, replace the brake shoes.
HINT: If any of the brake shoes have to be replaced, replace all of the rear brake shoes in order to maintain even braking.
3. Measure brake drum inside diameter.
Measure Brake Drum Inside Diameter:
Using a vernier calipers, measure the inside diameter of drum.
Standard inside diameter: 295.0 mm (11.614 inch)
Maximum inside diameter: 297.0 mm (11.693 inch)
If the drum is scored or worn, the brake drum may be lathed to the maximum inside diameter.
4. Inspect brake lining and drum for proper contact.
If the contact between the brake lining and drum is improper, repair the lining with a brake shoe grinder, or replace the brake shoe assembly.