G 2500 3/4 Ton Van V8-305 5.0L VIN M SFI (1997)
Brake Drum: Testing and Inspection
Measuring Inside Diameter
NOTE: 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 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.
Brake Drum Diameters
Original .................................................................................................................................................................................. 330.20 mm (13.00 inch)
Maximum Refinish ................................................................................................................................................................ 331.72 mm (13.06 inch)
Discard ................................................................................................................................................................................... 332.48 mm (13.09 inch)
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.
