Out-of-Round or Tapered

An out-of-round or tapered drum prevents accurate rear brake shoe adjustment and is likely to cause excessive wear of other brake parts due to its eccentric action. An out-of-round drum can also cause severe and irregular tire tread wear as well as a pulsating brake pedal. When the drum exceeds the specification limits in taper and/or out-of-round, refinish the drum to true up the braking surface. Out-of-round as well as taper and wear can be accurately measured with an inside micrometer and extension rods. When measuring a drum for out-of-round, taper, and wear, take measurements at the open and closed edges of the machined surface and at right angles (90 degrees) to each other.