INSPECTION

Whenever brake drums are removed, they should be inspected for scores, deep grooves, cracks and out of round.

Cracked drums must be replaced. However, cracks running circumferentially at the back corner of drum where the cast iron blends into the steel portion of the drum are of no consequence and drums should not be replaced.

Drum out-of-round can be measured with a dial indicator and extension rod. Out-of-round measurements exceeding .005" front drum and .006" rear drum, (total indicator reading) require turning or replacement of drum.

TURNING DRUMS

If irregularities in the braking surface of the drum cannot be removed with emery cloth or out of round exceeds .005" front drum and .006" rear drum (total indicator reading), the drum should be turned to .060" greater than the original inside diameter; that is, after being turned, the diameter should be 11.060" for all except 30, 31 and 32 series, or 9.560 on 30, 31, 32 and 33 series. Oversize brake linings must be used with turned drums.

REPLACING DRUMS

Whenever new drums are to be installed, the braking surface of the drum must be thoroughly cleaned with lacquer thinner to remove the rustproof coating.

BRAKE LINES

When replacing a damaged brake line, the damaged section should be cut off and repaired with steel brake tubing, listed under Group 8.964 in the Chassis Parts Book. Flare connections must be a double lap. Follow Flaring Tool Manufacturer's instructions for proper flaring of the double lap flare.

Refer to Figs. 11-15 and 11-16 for brake line routing and attachment.

BRAKE LINING

If linings are worn nearly flush with the rivets, new linings should be installed.

When brake lining replacement is necessary, it is recommended that both front or both rear linings be replaced at the same time.

FRONT BRAKE SHOES AND BACKING PLATE

Remove (Figs. 11-17 & 11-18)

1. Hoist car.
2. Remove the hub and drum assembly and the inner bearing inner race from the steering knuckle.
3. Remove the primary and secondary shoe return springs and the actuating link.
4. Remove brake shoe hold-down springs, pins and washers and the adjuster lever and return spring.
5. Spread shoes to clear wheel cylinder links, then remove the primary and secondary shoes as an assembly.
6. Remove the primary to secondary shoe spring and the adjusting screw.
7. If the front backing plate is to be removed, proceed as follows:
   1. Loosen lock tab from anchor pin, then remove the anchor pin bolt.
   2. Remove the brake hose from the brake line.
   3. Remove the wheel cylinder and brake hose from the backing plate.
   4. Remove the plain arm to steering knuckle to backing plate bolts and nuts, then remove the backing plate.

REAR BRAKE SHOES AND BACKING PLATE

Remove

1. Hoist car, remove wheel and brake drum.
2. Disconnect the parking brake cable from the operating lever.
3. Remove the brake shoe return springs, actuating link and guide.
4. Remove the brake shoe hold-down springs, the adjuster lever and return spring and the parking brake lever strut and spring.
5. Spread shoes to clear wheel cylinder links, then remove the brake shoes as an assembly.
6. If necessary to remove the rear backing plate, proceed as follows:
   1. Remove the axle shaft. (Refer to AXLE SHAFT-REMOVE Section 9)
   2. Remove brake line from wheel cylinder, remove wheel cylinder from backing plate.
   3. Disconnect the parking brake cable from the backing plate.
   4. Remove the backing plate.

Cleaning and inspection

1. Inspect linings for wear. If linings are worn nearly flush with rivets, new linings should be installed.
2. Check wheel cylinder for leakage by loosening the boot on 34, 35, 36, 38 and 39 series or by removing the link on 30, 31, 32 and 33 series. If leak exists, remove wheel cylinder for service or replacement.
3. Clean inner surfaces of brake backing plates and all shoe contacting points.
4. Clean exposed portions of parking brake cables.
5. Disassemble the adjusting screw assembly. Clean and inspect as follows:
   1. Check thrust washer and mating surfaces for burrs or excessive wear.
   2. Inspect teeth on sprocket for wear.
   3. Remove all foreign material from adjusting screw and nut. Nut must rotate freely on threads.
6. Check the foot of the adjuster lever for wear. Replace if necessary.
7. Check the override pivot for wear or deformed parts.
8. Check brake drum for buildup of rust and dirt at outer circumference. Remove buildup so that drums can be installed over preadjusted linings. Check drum for cracks and an out-of-round condition.

FRONT BRAKE AND BACKING PLATE - Install

1. If the front backing plate was removed, install as follows:
   1. Position the backing plate on the steering knuckle. Install the two plain arm to steering knuckle to backing plate bolts and nuts. Torque nuts 100 to 140 ft. lbs. on 34, 35, 36, 38 and 39 series and 60 to 82 ft. lbs. on 30, 31, 32 and 33 series.
   2. Install the wheel cylinder. Torque attaching nuts 8 to 16 ft. lbs. Connect brake hose to brake line. Tighten brake line fittings 8 to 12 ft. lbs.
   3. Install the brake hose retainer.
   4. Position a new lock tab over the anchor pin bolt and install bolt.
   5. Align the slot in the lock tab with the boss on the wheel cylinder. Torque anchor pin bolt 120 to 145 ft. lbs. on 34, 35, 36, 38 and 39 series, 80 to 105 ft. lbs. on 30, 31, 32 and 33 series. Bend lock tab down until it contacts the anchor pin bolt head.
2. Lubricate the adjusting screw threads, thrust washer mating surfaces and backing plate ledges with brake lubricant, Part No. 987786.
3. Assemble the adjusting screw.
4. Attach the primary to secondary shoe spring to the shoes, and install the adjusting screw. The primary to secondary shoe spring must not contact the adjusting screw sprocket.
5. Position shoe assembly on the backing plate. Be sure wheel cylinder links are properly positioned in the shoe notches.
6. Position the upper end of the actuating link on the brake shoe guide.
7. Engage the actuating link with the override pivot then position the adjuster lever and re-' turn spring on the secondary shoe. Fasten with the hold-down spring assembly.
8. Install the remaining hold-down springs.
9. Install the primary and secondary brake shoe return springs.
10. Adjust brake shoes as outlined under ADJUSTMENTS - BRAKE SHOE.
11. Install the front hub and drum assembly. Adjust wheel bearings as outlined under WHEEL BEARING ADJUSTMENT, Section 9.
12. If wheel cylinder was removed, bleed brakes.
13. Check fluid level in master cylinder. Fluid level should be no more than 1/4" below the reservoir opening.
14. Check brake pedal travel to be sure it is within specifications, then road test car for proper operation of the brake system.

 REAR BRAKE AND BACKING PLATE - Install

1. If the backing plate was removed, install as follows:
   1. Install wheel cylinder on backing plate. Torque attaching bolts 8 to 12 ft. lbs.
   2. Position backing plate on axel housing and install the axel shaft. Torque the backing plate to axel housing 40 to 55 ft. lbs.
   3. Install the parking brake cable on the backing plate.
2. Lubricate the adjusting screw threads, thrust washer mating surfaces and backing plate ledges with brake lubricant, Part No. 987786.
3. Pull parking brake cables forward and rearward through conduits, lubricate freely with Lithium Soap Grease and return cable to normal position. Remove any excess lubricant.
4. Install the parking brake lever to the secondary shoe.
5. Assemble the adjusting screw.
6. Attach the primary to secondary shoe spring to the shoes, and install the adjusting screw. The primary to secondary shoe spring must not contact the adjusting screw sprocket.
7. Position shoe assemblies on the backing plate. Be sure wheel cylinder links are properly positioned in the shoe notches. Install the parking brake strut and spring.
8. Position the upper end of actuating link over the anchor pin.
9. Engage the actuating link with the override pivot, then position the adjuster lever and return spring on the secondary shoe. Fasten with the hold-down spring assembly.
10. Install the remaining hold-down spring.
11. Install the parking brake cable on the parking brake lever.
12. Install the primary and secondary brake shoe return springs.
13. Adjust brake shoes as outlined under ADJUSTMENTS - BRAKE SHOE.
14. Install the re ar brake drums and wheels.
15. Adjust the parking brake.
16. If the wheel cylinder was removed, bleed brakes.
17. Check fluid level in master cylinder. Fluid level should be no more than 1/4" below the reservoir opening.
18. Check brake pedal travel to be sure it is within specifications, then road test car for proper operation of the brake system.

POWER BRAKES

DESCRIPTION

Four different power brake units are used. The 30, 31 and 32 series use a Moraine or a Kelsey-Hayes brake. The 33, 34, 35, 36, 38 and 39 series use a Moraine or a Bendix brake.

The Moraine vacuum units are identical, with the exception of the mounting and the operating rod assembly, and service procedures for both units will be covered under one write-up.

Internally, all units differ in construction but all units are designed to seal off atmospheric pressure when the pedal is in the released position. The hydraulic master cylinder on the power brake units are similar in construction and service to the standard brake master cylinder. For removal and service of the power brake master cylinder, refer to MASTER CYLINDER.

A vacuum check valve traps vacuum inside the power brake unit, at the highest manifold vacuum available, making possible brake application after the engine has been shut off for several hours or more. If the engine should stall, several applications of the brakes can still be made with vacuum assist. After the vacuum supply is exhausted, brake applications can still be made; however, more effort is required due to the lack of vacuum assist.

MINOR SERVICE OPERATIONS

BRAKE PEDAL OR BRACKET - Remove and Install

The power brake pedal and mounting bracket is attached as shown in Fig. 11-21 or Fig. 11-22.

To install, lubricate nylon bushings and clevis pin with lubricant, Part No. 567196. Torque pivot pin nut on 33, 34, 351 36, 38 and 39 series 10 to 18 ft. lbs. On 30, 31 and 32 series, check and adjust brake pedal height if necessary. Check and adjust stop lamp switch if necessary.

POWER BRAKE UNIT - Remove and Install (Figs. 11 - 21 or 11 - 23)

1. Disconnect hydraulic line. Plug or tape line to prevent dirt from entering the hydraulic system.
2. Disconnect the vacuum line from the vacuum check valve.
3. Disconnect 'the operating rod from the power brake pedal.
4. Remove the four vacuum cylinder unit to cowl attaching nuts.
5. To install, reverse removal procedure. Torque the vacuum cylinder to cowl bolts 20 to 27 ft. lbs. Fill master cylinder with Brake Fluid Super No. 11 and bleed entire system. (See BLEEDING OF LINES) On 30, 31 and 32 series, check and adjust brake pedal height. If necessary.