- Remove the wheel and drum.
- Inspect the shoes for proper thickness. The lining should be at least 1 / 32 in. (0.8mm) above the rivet head for riveted brakes and 1 / 16 in. (1.6mm) above the mounting surface for bonded brake linings.
- Inspect the linings for even wear, cracking and scoring. Replace as necessary.
REMOVAL & INSTALLATION
See Figures 1 through 11
The brake shoes should be replaced in axle pairs. Failure to replace the component in pairs may cause unequal braking action and premature wear.
- Raise and safely support the vehicle.
- Remove the tire and wheel assemblies, then remove the brake drum.
If unsure of spring positioning, finish one side before starting the other and use the untouched side as a guide.
- Using tool J 8049, J 29840 or equivalent brake spring remover and installer, unfasten the primary and secondary shoe return springs from the anchor pin, but leave them installed in the shoes.
- Remove the hold-down springs, and pins using suitable pliers or brake tool.
- While lifting up on the actuator lever, remove the actuator link.
- Remove the actuator lever, lever return spring and the bearing sleeve.
- Remove the parking brake strut and spring.
- Remove the brake shoes, which are held together by the lower spring, after disconnecting the parking brake cable from the backing plate.
- Disconnect the adjusting screw assembly and adjusting screw spring from the brake shoes.
- Remove the retaining ring, pin and parking brake lever from the secondary brake shoe.
- Lift the wheel cylinder dust boots and inspect for fluid leakage.
- Thoroughly clean and dry the backing plate.
- Remove, clean and dry all parts still on the old shoes with denatured alcohol. Lubricate the star wheel shaft threads and transfer all the parts to the new shoes in their proper locations.
- To prepare the backing plate, lubricate the bosses, anchor pin and parking brake actuating lever pivot surface lightly with brake lubricant GM part no. 1052916, or equivalent.
- Install the parking brake lever on the secondary shoe with the pin and retaining ring.
- Install the adjusting screw assembly and adjusting screw spring on the shoe and lining assembly.
- Position the shoe and lining assemblies after attaching the parking brake cable.
- Spread the shoes apart, install the parking brake strut and strut spring. The end without the strut spring should engage the parking brake lever and secondary shoe and lining. The end with the strut spring should engage the primary shoe and lining.
In the next step, the bearing sleeve must be installed between the secondary and lining and the actuator lever. Refer to the accompanying figure.
- Install the bearing sleeve, actuator lever and lever return spring.
- Install the hold-down pins and springs.
- Fasten the actuator link on the anchor pin. While holding up the lever, fasten the actuator link into the lever.
- Secure the shoe return springs, using tool J 8057 or equivalent pliers.
- Adjust the brakes using the procedure located in this section.
- Aligning the marks made during removal, install the brake drum.
- Install the tire and wheel assembly.
- Carefully lower the vehicle, then tighten the lug nuts to 103 ft. lbs. (140 Nm).
- Adjust the parking brake, as outlined later in this section.
The drum brakes are designed to self-adjust when applied with the car moving in reverse. However, they can also be adjusted manually. This manual adjustment should also be performed whenever the linings are replaced.1982-86 Vehicles
See Figure 12
- Raise and safely support the vehicle.
- Remove the tire and wheel assembly.
- Remove the drum, then measure the inside diameter of the brake drum with a drum-to-brake shoe gauge, J 21177-A or equivalent.
- Position the tool on the brake linings, as shown in the accompanying figure, with the setting obtained in Step 3 and adjust the brake shoes so that the lining contacts the inside part of the tool.
- Use a punch to knock out the stamped area on the brake drum. If this is done with the drum installed on the car, the drum must then be removed to clean out all metal pieces. After adjustments are complete, obtain a hole cover from your dealer (Part no. 4874119 or the equivalent) to prevent entry of dirt and water into the brakes.
- Use an awl or an adjusting tool especially made for the purpose to turn the brake adjusting screw star wheel. Expand the shoes until the drum can just barely be turned by hand.
- Back off the adjusting screw 12 notches. If the shoes still are dragging lightly, back off the adjusting screw one or two additional notches. If the brakes still drag, the parking brake adjustment is incorrect or the parking brake is applied. Fix and start over.
- Install the hole cover into the drum.
- Check the parking brake adjustment.
On some models, no marked area or stamped area is present on the drum. In this case, a hole must be drilled in the backing plate:
- All backing plates have two round flat areas in the lower half through which the parking brake cable is installed. Drill a 1 / 2 in. (13mm) hole into the round flat area on the backing plate opposite the parking brake cable. This will allow access to the star wheel.
- After drilling the hole, remove the drum and remove all metal particles. Install a hole plug (Part no. 4874119 or the equivalent) to prevent the entry of water or dirt.
- Install the brake drum and the wheel and tire assembly, then carefully lower the vehicle.
See Figure 12
- Raise and support the vehicle safely.
- Matchmark the relationship between the wheel to the axle flange to insure proper balance upon reassembly, then remove the tire and wheel assembly.
- Matchmark the relationship of the drum to the axle flange, then remove the brake drum.
- Measure the drum inside diameter using brake shoe gauge J 12177-A, or equivalent.
Turning the star wheel, adjust the shoe and lining diameter to be:
0.050 in. (1.27mm) less than the inside drum diameter for each wheel for 1987-90 vehicles.
- Install the drums and wheels, aligning the previous marks.
- Carefully lower the vehicle.
- Tighten the wheel nuts to 100 ft. lbs. (136 Nm).
- Make several alternate forward and reserve stops applying firm force to the brake pedal until ample pedal reserve is built up.