GM Service Manual Online
For 1990-2009 cars only
  1. Remove the brake drums. Refer to Brake Drum Replacement in Drum Brakes.
  2. Use a depth gauge in order to measure the thickness of the brake shoe lining.
  3. Replace the brake shoes if the brake shoe lining is less than 0.76 mm (0.030 in) from the brake shoe or any one of the brake shoe rivets.