Parking Brake System: Testing and Inspection

CABLE INSPECTION
Check the parking brake for free operation. The brake lever must return to the released position without sticking or binding. If a problem is present, check the cable toutings for kinks or binding.

LINING INSPECTION
Replace the brake shoe and the lining assemblies whenever the thickness of any lining is worn to within 0.76 mm (0.030 inch) of the shoe. For riveted shoe and lining assemblies, replace when the lining is worn to within 0.76 mm (0.30 inch) of any rivet head.

DRUM INSPECTION
Any time the parking brake drum is removed, thoroughly clean and inspect it for cracks, scores, deep grooves, and out-of-round.

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

INSIDE DIAMETER CHECK
Measure the inside diameter of the 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.

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