Caution: Refer to Brake Dust Caution in the Preface section.
- Clean the brake shoe lining contact surface of the brake drum
with denatured alcohol or an equivalent approved brake cleaner.
- Using a brake drum micrometer calibrated in thousanths-of-an-inch, measure
and record the largest diameter of the brake drum at four or more points, equally
spaced around the drum.
Ensure the measurements are only taken within the brake shoe lining contact
area. The micrometer must be positioned the same distance from the outside edge
of the drum for each measurement.
- Compare the largest diameter measurement recorded to the following specifications:
Specification
• | Brake drum maximum allowable diameter after refinishing: 230.50 mm
(9.075 in). |
• | Brake drum discard diameter: 231.0 mm (9.094 in). |
- If the largest diameter measurement of the brake drum is less than the
maximum allowable diameter after refinishing specification; the drum may be refinished,
depending upon surface and wear conditions.
- If the largest diameter measurement of the brake drum is equal to or
greater than the maximum allowable diameter after refinishing specification; the
drum may not be refinished.
- If the largest diameter measurement of the brake drum is equal to or
greater than the discard diameter specification; the drum requires replacement.