See Figure 1
Adjustment procedures are given here for drum brakes only. No adjustment is possible on disc brakes since they are inherently self-adjusting type. All drum brakes are of the self-adjusting type, also. All that is normally required to adjust the brakes is to stop the car moderately hard several times while backing up. If more adjustment is required, however, or if the brakes have been replace, use the following procedure:
- Raise the rear of the vehicle 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 parts distributor to plug the punched holes now in the backing plats. Many vehicles will already have the holes punched and plugs installed.
Adjustment to tighten:
- Insert a brake adjusting spoon into the hole.
- Turn the star-shaped adjusting screw inside the drum with the spoon, until the wheel has a slight drag. Do this to both wheels until there is equal drag on each wheel. DO NOT make the adjustment over-tight!
Adjustment to loosen and remove the drum:
- Insert a brake adjusting spoon and small prybar to hold the adjusting lever away from the sprocket.
- Back off each adjusting screw until the drum turns freely. If the brake shoes drag with the adjusters backed off all the way, the parking brake cables could be excessively tight.
The pedal travel is measured as the distance which the pedal moves towards the floor from the fully released position. Inspection should be made with the pedal firmly depressed and the brake system cold. Pedal travel should be 2 1 / 2 in. on 1970-74 models, 2 1 / 4 in. on 1975-84 models, 2 3 / 4 in. on 1985-87 models and 3 1 / 3 in. on Hydro-boost systems.
If equipped with power brakes, pump the 3 times with the engine OFF to remove vacuum reserve before checking pedal travel.
- Under the dash, remove the pushrod-to-pedal clevis pin.
- Loosen the pushrod adjusting locknut and adjust the pushrod.
- After the correct travel is established, tighten the locknut.
- Engage the pushrod and secure using the clevis pin.