GM Service Manual Online
For 1990-2009 cars only
  1. Replace the brake shoe and the lining assemblies whenever the thickness of any lining is worn to within 0.76 mm (0.030 in) of the shoe.
  2. Replace the riveted brake shoe and the lining assemblies whenever the lining is worn to within 0.76 mm (0.030 in) of any rivet head.