Brake Drum Inspection - Surface Finish

Any time you remove the rear brake drums, thoroughly clean and inspect them for cracks, scores, deep grooves and out-of-roundness.

SURFACE FINISH
Slight scoring can be cleaned up with a fine emery cloth. Heavy or extensive scoring causes excessive brake shoe wear. The drum braking surface will need to be machined to remove these scores.
If the rear brake drum is grooved and the brake shoes are slightly worn, the drum should not be machined. Instead, polish the rear brake drum surface with a fine emery cloth. Eliminating all of the rear brake drum grooves and ridges on the brake shoes would require removing too much metal and shoe material. Satisfactory service can be obtained by leaving them alone.

INSIDE DIAMETER CHECK
Measure the inside diameter of the rear brake drum at two or more places around the circumference of the braking surface. The measurements must be made at the same distance in from the edge of the drum. Compare the results with the Rear Brake Drum Diameters.

TAPER CHECK
Measuring a rear brake drum for taper involves taking measurements at the inner and outer edges of the machined surface at two or more places around the drum. These measurements should be equal.