GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Aveo 🢒 General Information 🢒 General Information 🢒 Brake Drum Surface and Wear Inspection

Caution: Refer to Brake Dust Caution in the Preface section.

Thoroughly clean and inspect the brake drums for cracks, scores, deep grooves, or an out-of-round condition.

    • A cracked drum is unsafe for further service and must be replaced. Do not attempt to weld a cracked drum. Smooth out any slight scores.
    • Heavy or extensive scoring will cause excessive brake lining wear and may require refinishing the drum braking surface.
    • If the brake linings are slightly worn but are still reusable and the drum is grooved, polish the drum with a fine emery cloth but do not refinish the drum. Eliminating all grooves in the drum and smoothing the ridges on the lining would remove too much metal and lining. If left alone, the grooves and ridges match, and satisfactory service can be obtained. If the brake linings need to be replaced, refinish a grooved drum. A grooved drum, used with a new lining, will not only wear the lining, but also will make it difficult, if not impossible, to obtain proper brake performance.
    • An out-of-round drum makes accurate brake shoe adjustment impossible and is likely to cause excessive wear of other parts of the brake mechanism. An out-of-round drum can also cause severe and irregular tire tread wear, as well as a pulsating brake pedal.
    • The extent to which a drum is worn or out-of-round can be measured accurately with an inside micrometer fitted with the proper extension rods. When measuring a drum for wear or the radial runout, take measurements from the inside edge to the outside edge of the machined surface at 90 degree intervals around the circumference of the drum.

Inspection Procedure
  1. Remove the brake drum. Refer to Brake Drum Replacement .
  2. Clean the drum.
  3. Inspect the drum for cracks or damage.

    4. Object Number: 1241951 Size: SH
  4. Measure the inside diameter of the drum.

    5. Specification
    The maximum inner diameter of the drum is 201 mm (7.91 in).

  5. If the inner diameter of the drum is greater than the specification, replace the drum.
  6. Measure the radial runout of the drum.

    7. Specification
    The maximum radial runout of the drum is 0.04 mm (0.002 in).

  7. If the drum exceeds the maximum radial runout, refinish the drum.
  8. Install the drum. Refer to Brake Drum Replacement .