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Rear Disk Brake Parking Brake Adjustment

Rear Parking Brake and Adjustment

I had the question asked of me.  "What does the rear parking brake look like?"  So when I had it off cleaning out the mud that had gotten into there and readjusting it I figured I would take a couple pics for everyone.

Tire Removed
Tire removed.
Brake drum removed
Brake drum removed, those are the emergency brake shoes that you see.
Inside of rear disk brake drum
The inside of the rear disk is the same as a drum brake.

DESCRIPTION
The parking bake is a hand lever and cable operated system used to apply the rear brakes.

OPERATION
A hand operated lever in the passenger compartment is the main application device. The front cable is connected between the hand lever and the tensioner. The tensioner rod is attached to the equalizer, which is the connecting point for the rear cables (Fig. 60).  The rear cables are connected to the actuating lever on each secondary brake shoe. The levers are attached to the brake shoes by a pin either pressed into, or welded to the lever. A clip is used to secure the pin in the brake shoe. The pin allows each lever to pivot independently of the brake shoe. To apply the parking brakes, the hand lever is pulled upward. This pulls the rear brake shoe actuating levers forward, by means tensioner and cables. As the actuating lever is pulled forward, the parking brake strut (which is connected to both shoes), exerts a linear force against the primary brake shoe. This action presses the primary shoe into contact with the drum. Once the primary shoe contacts the drum, force is exerted through the strut. This force is transferred through the strut to the secondary brake shoe causing it to pivot into the drum as well. A gear type ratcheting mechanism is used to hold the lever in an applied position. Parking brake release is accomplished by the hand lever release button. A parking brake switch is mounted on the parking brake lever and is actuated by movement of the lever. The switch, which is in circuit with the red warning light in the dash, will illuminate the warning light whenever the parking brakes are applied. Parking brake adjustment is controlled by a cable tensioner mechanism. The cable tensioner, once adjusted at the factory, should not need further adjustment under normal circumstances. Adjustment may be required if a new tensioner, or cables are installed, or disconnected.

Parking brake components

DIAGNOSIS AND TESTING - PARKING BRAKE
NOTE:
Parking brake adjustment is controlled by a cable tensioner. Once the tensioner is adjusted at the factory, it should not require further attention. However, there are two instances when adjustment will be required. The first is when a new tensioner, or cables have been installed. And the second, is when the tensioner and cables are disconnected for access to other brake components.

The parking brake switch is in circuit with the red warning lamp in the dash. The switch will cause the lamp to illuminate only when the parking brakes are applied. If the lamp remains on after parking brake release, the switch or wires are faulty, or cable tensioner adjustment is incorrect. In most cases, the actual cause of an improperly functioning parking brake (too loose/too tight/won’t hold), can be traced to a parking brake component. The leading cause of improper parking brake operation, is excessive clearance between the parking brake shoes and the shoe braking surface. Excessive clearance is a result of lining and/or drum wear, drum surface machined oversize, or inoperative adjuster components. Excessive parking brake lever travel (sometimes described as a loose lever or too loose condition), is the result of worn brake shoes, improper brake shoe adjustment, or improperly assembled brake parts. A condition where the parking brakes do not hold, will most probably be due to a wheel brake component. Items to look for when diagnosing a parking brake problem are:

1.
Rear brake shoe wear.
2.
Drum surface machined oversize.
3.
Front cable not secured to lever.
4.
Rear cable not attached to lever.
5.
Rear cable seized.
6.
Brake shoes reversed.
7.
Parking brake strut not seated in shoes.
8.
Parking brake lever not seated.
9.
Parking brake lever bind.
10.
Adjuster screws seized.
11.
Adjuster screws reversed.

Parking brake adjustment and parts replacement procedures are described in the Parking Brake section.

Brake adjustment

 ADJUSTMENT - WITH ADJUSTING TOOL
Adjustment can be made with a standard brake gauge or with adjusting tool. Adjustment is performed with the complete brake assembly installed on the backing plate.
(1) Be sure parking brake lever is fully released.
(2) Raise vehicle so rear wheels can be rotated freely.
(3) Remove plug from each access hole in brake support plates.
(4) Loosen parking brake cable adjustment nut until there is slack in front cable.
(5) Insert adjusting tool through support plate access hole and engage tool in teeth of adjusting screw star wheel (Fig. 68).
(6) Rotate adjuster screw star wheel (move tool handle upward) until slight drag can be felt when wheel is rotated.
(7) Push and hold adjuster lever away from star wheel with thin screwdriver.
(8) Back off adjuster screw star wheel until brake drag is eliminated.
(9) Repeat adjustment at opposite wheel. Be sure adjustment is equal at both wheels.
(10) Install support plate access hole plugs.
(11) Adjust parking brake cable and lower vehicle.
(12) Depress park brake lever and make sure park brakes hold the vehicle stationary.
(13) Release park brake lever.

 This page last updated: 16-Apr-2008

Content and Design © 2002-present WanderingTrail,  Ron Seegert
Common Sense and Safety should always be observed when working on your vehicle or doing modifications. Jackstands, wheel blocks, disconnecting the battery are a few of the basic safety precautions that should be used and may not be mentioned in the write ups on this site. You are responsible for your own installation, these write ups are a helpful guideline and should not be taken as an official installation instruction. My write up may be different from the kits currently out there, so alwasy double check the manufacturers installation instructions when installing anything. I try to keep the site up to date with changes that have occured as I discover them, but may not have the latest unless someone lets me know. If you feel that an install is above your capabilities after reading my write ups, I recommend getting together with a club and getting some help. Only a few times have I needed to employe some actual help from a shop to get something done. Usually welding or A/C work.
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