Measure the inside diameter of the drum with an inside micrometer at a number of different positions. Compare it with the specifications listed in the Brake Specifications chart in this section. If the drum is worn past the limit at any point, it must be replaced. Additionally, the diameter should be constant at all points measured. An out-of-round condition may cause vibration under braking.
Mitsubishi gives no limits for machining drums to remove uneven wear other than the absolute maximum diameter (wear limit). If the drum is worn unevenly around its diameter or has wear grooves, you may be able to salvage it by having it machined BUT machining must not increase the diameter past the specified limits. If it does, the drum must be replaced.
| Fig. 1: Use a micrometer or ruler to measure the inside
diameter of the brake drum at several locations around the circumference
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Drums, particularly the larger ones, can crack. Check the inner and outer surfaces and the area around the wheel lug holes for any sign of hairline cracks. Obviously, if any are found, the drum is useless.
