Surface Finish

Normal, light scoring of drum surfaces less than 1.5 mm (1/16 inch) deep is not detrimental to brake operation. Smooth out any light scores. Heavy or extensive scoring will cause excessive lining wear, and resurfacing the drum braking surface might be necessary.

If the linings are slightly worn (but still usable) and the drum is grooved, polish the drum with a fine emery cloth; do not refinish it. Eliminating all drum grooves and smoothing the lining ridges would require removing too much metal and lining. If left alone, the grooves and ridges match and satisfactory service can be obtained. If brake linings are to be replaced, refinish a grooved drum. If a grooved drum is used with new lining, it will wear the lining, making proper brake performance difficult to obtain.