After removing the brake drum, inspect the brake shoes. If the lining is worn down to within 1 / 32 in. (0.8mm) of a rivet, the shoes must be replaced.
This figure may disagree with your state's automobile inspection laws.
If the brake lining is soaked with brake fluid or grease, it must be replaced. If this is the case, the brake drum should be sanded with crocus cloth to remove all traces of brake fluid, and the wheel cylinders should be rebuilt. Clean all grit from the friction surface of the drum before replacing it.
If the lining is chipped, cracked, or otherwise damaged, it must be replaced with a new lining.
Always replace the brake linings in sets of two on both ends of the axle. Never replace just one shoe, or both shoes on one side and not the other. When replacing the brakes, it is a good idea to replace one side at a time so that you always have an example to refer to if you get confused during reassembly.
Check the condition of the shoes, retracting springs, and hold-down springs for signs of overheating. If the shoes or springs have a slight blue color, this indicates overheating and replacement of the shoes and springs is recommended. The wheel cylinders should be rebuilt as a precaution against future problems.
REMOVAL & INSTALLATION
See Figures 1 through 11
- Loosen the lug nuts on the wheel to be serviced, raise and support the car, and remove the wheel and brake drum.
It is not really necessary to remove the hub and wheel bearing assembly from the axle, but it does make the job easier. If you can work with the hub and bearing assembly in place, skip down to Step 12.
- Remove the four hub and bearing assembly retaining bolts and remove the assembly from the axle.
- Remove the return springs from the shoes with a pair of needle nose pliers. There are also special brake spring pliers for this job.
- Remove the hold-down springs by gripping them with a pair of pliers, then pressing down and turning 90°. There are special tools to grab and turn these parts, but pliers work fairly well.
- Remove the shoe hold-down pins from behind the brake backing plate. They will simply slide out once the hold-down spring tension is relieved.
- Lift up the actuator lever for the self-adjusting mechanism and remove the actuating link. Remove the actuator lever, pivot, and the pivot return spring.
- Spread the shoes apart to clear the wheel cylinder pistons and remove the parking brake strut and spring.
- If the hub and bearing assembly is still in place, spread the shoes far enough apart to clear it.
- Disconnect the parking brake cable from the lever. Remove the shoes, still connected by their adjusting screw spring, from the car.
- With the shoes removed, note the position of the adjusting spring and remove the spring and adjusting screw.
- Remove the C-clip from the parking brake lever and remove the lever from the secondary shoe.
- Use a damp cloth to remove all dirt and dust from the backing plate and brake parts. See the warning about brake dust in the drum removal procedure.
- Check the wheel cylinders by carefully pulling the lower edges of the wheel cylinder boots away from the cylinders. If there is excessive leakage, the inside of the cylinder will be moist with fluid. If leakage exists, a wheel cylinder overhaul or replacement is in order. Do not delay, because brake failure could result.
A small amount of fluid will be present to act as a lubricant for the wheel cylinder pistons. Fluid spilling from the boot center hole, after the piston is removed, indicates cup leakage and the necessity for cylinder overhaul.
- Check the backing plate attaching bolts to make sure that they are tight. Use fine emery cloth to clean all rust and dirt from the shoe contact surfaces on the plate.
- Lubricate the fulcrum end of the parking brake lever with brake grease specially made for the purpose. Install the lever on the secondary shoe and secure with C-clip.
- Install the adjusting screw and spring on the shoes, connecting them together. The coils of the spring must not be over the star wheel on the adjuster. The left and right hand springs are not interchangeable. Do not mix them up.
- Lubricate the shoe contact surfaces on the backing plate with the brake grease. Be certain when you are using this stuff that none of it actually gets on the linings or drums. Apply the same grease to the point where the parking brake cable contacts the plate. Use the grease sparingly.
- Spread the shoe assemblies apart and connect the parking brake cable. Install the shoes on the backing plate, engaging the shoes at the top temporarily with the wheel cylinder pistons. Make sure that the star wheel on the adjuster is lined up with the adjusting hole in the backing plate, if the hole is back there.
- Spread the shoes apart slightly and install the parking brake strut and spring. Make sure that the end of the strut without the spring engages the parking brake lever. The end with the spring engages the primary shoe (the one with the shorter lining).
- Install the actuator pivot, lever and return spring. Install the actuating link in the shoe retainer. Lift up the actuator lever and hook the link into the lever.
- Install the hold-down pins through the back of the plate, install the lever pivots and hold-down springs. Install the shoe return springs with a pair of pliers. Be very careful not to stretch or otherwise distort these springs.
- Take a look at everything. Make sure the linings are in the right place, the self-adjusting mechanism is correctly installed, and the parking brake parts are all hooked up. If in doubt, remove the other wheel and take a look at that one for comparison.
- Measure the width of the linings, then measure the inside width of the drum. Adjust the linings by means of the adjuster so that the drum will fit onto the linings.
- Install the hub and bearing assembly onto the axle if removed. Tighten the retaining bolts to 128 ft. lbs. (51 Nm).
- Install the drum and wheel, tightening the lug nuts to 100 ft. lbs. (136 Nm). Adjust the brakes using the procedure given in this section. Be sure to install a rubber hole cover in the knock-out hole after the adjustment is complete. Adjust the parking brake.
- Lower the car and check the pedal for any sponginess or lack of a hard feel. Check the braking action and the parking brake. The brakes must not be applied severely immediately after installation. They should be used moderately for the first 200 miles of city driving or 1000 miles of highway driving, to allow the linings to conform to the shape of the drum.
See Figure 12
- Raise and support the vehicle safely.
- 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 0.030 in. (0.76mm) less than the inside drum diameter for each wheel.
- Install the drums and wheels, aligning the previous marks.
- Carefully lower the vehicle.
- Tighten the wheel nuts to 100 ft. lbs. (140 Nm).