There is no adjustment provision on hydraulic disc brakes; they are inherently self-adjusting.
DRUM BRAKE SHOES
See Figures 1 and 2
Drum brakes are self-adjusting, but provision is made for manual adjustment as follows:
- Jack up the rear of the car and support it with jackstands.
- The inner sides of the brake backing plates have a lanced area, oblong in shape. Knock this area out with a punch - you will have to remove the brake drum to clean out any metal pieces that will be deposited by the punch, and you will have to purchase rubber plugs at a GM dealer or auto supply store to plug the punched holes in the backing plates. Many cars will already have the holes punched and plugs installed.
- Turn the star-shaped adjusting screw inside the drum with a brake spoon, until the wheel can just be turned by hand. Do this to both wheels until there is equal drag on each wheel.
- Insert a brake adjusting spoon into the hole, along with a small screwdriver to hold the adjuster lever away from the sprocket. Back off each adjusting screw about 25 notches or to a very slight drag. If you still hear and feel the brake shoes dragging slightly when you turn the wheels by hand, back off another one or two notches. If there is still excess drag on the drums, the parking brake cables could be excessively tight.
- Install the rubber plugs into the adjusting holes. Check the parking brake adjustment.