GM Service Manual Online
For 1990-2009 cars only

Although the drum brakes are of the self-adjusting type, some adjustments for proper shoe-to-drum clearance may be required when brake shoes have been replaced or the drum has been removed for other service.

Adequate adjustment may be accomplished by pressing the brake pedal 3 to 5 times with 30 kg (66 lbs) of pressure after all service is completed.

Check the rear wheels for dragging. After the adjustment is completed, road test the vehicle.