Brake Drum

Inspect the inside of the brake drum for scratches and uneven or abnormal wear.
Repair minor damage or replace if damage is excessive.
Measure the inside diameter of the brake drum using Brake Drum Micrometer or equivalent.

Fig 1: Measuring Inside Diameter Of Brake Drum
The standard inner drum diameter is 7.87 in. (200 mm) .
The maximum diameter is 7.91 in. (201 mm) .

Fig 2: Illustrating Brake Drum Diameter

CAUTION: Be sure to check the drum-to-shoe contact after repairing or replacing the brake drum.
Check the brake linings for peeling, cracks, or extremely uneven wear.
If the brake lining thickness is less than 0.04 in. (1.0 mm), replace the brake shoes.