Brakes - Master Cylinder

STANDARD AND POWER

The standard and power brake master cylinders are a sealed type, consisting of a flexible diaphragm located between the fluid reservoir and the vented filler cover. This allows the brake fluid in the system to be sealed from outside air and dust while maintaining normal atmospheric pressure on the fluid in the fluid reservoir.

A Bendix master cylinder is used on the Bendix power brake and can be identified by the screw type master cylinder cover. A Moraine master cylinder is used with all standard and Moraine or Kelsey-Hayes power brakes and can be identified with the bail-type master cylinder cover.

Remove (Fig. 11-16)

The standard brake master cylinder, on 33, 34 and 35 series, can be removed without disconnecting the push-rod and clevis. The hydraulic master cylinder, on all series equipped with power brakes, can be removed and serviced without removing the vacuum cylinder from the car.

  1. Be sure the area around master cylinder is clean, then disconnect the hydraulic lines at the master cylinder. Plug or tape end of line to prevent entrance of dirt, or loss of brake fluid.
  2. On 30, 31 and 32 series, remove the push-rod to brake pedal clevis pin.
  3. Remove master cylinder by removing the attaching nuts.
  4. Drain master cylinder.

Fig. 11-11 Master Cylinder (Moraine)

Install

  1. To install the standard brake master cylinder on 33, 34 and 35 series:
    1. Lubricate push rod with a light film of lubricant, Part No. 567196 to facilitate positioning of rubber boot on push-rod after master cylinder has been installed
    2. Position master cylinder against cowl, push boot onto push-rod and guide push-rod into master cylinder piston cavity.
    3. Install the attaching nuts and lockwashers. Torque nuts 20 to 27 ft. lbs.
    4. From inside car, pull boot along push-rod toward clevis until boot is fully extended. Check brake pedal as outlined under BRAKE PEDAL ADJUSTMENTS (Standard Brake).
  2. To install the standard brake master cylinder on 30, 31 and 32 series:
    1. Position the master cylinder against cowl and install the attaching nuts. Torque nuts 20 to 28 ft. lbs.
    2. Install the push-rod to brake pedal clevis pin.
  3. To install the power brake master cylinder:
    1. Position a new filter on the flange of the master cylinder. (Moraine Power Brake Only)
    2. Position master cylinder so that push-rod enters cavity in master cylinder piston.
    3. Install master cylinder attaching nuts and lockwashers. Torque 20 to 27 ft. lbs.
  4. Install hydraulic line to master cylinder.
  5. Fill master cylinder reservoir with Brake Fluid, Super No. 11 and bleed all wheel cylinders as outlined under BLEEDING OF LINES.

NOTE

If a new push-rod was installed, adjust push-rod as outlined under PUSHROD ADJUSTMENT.

Disassembly (Figs. 11-11 & 11-12)

  1. Standard brake - remove boot from master cylinder.
  2. Remove the retaining ring from the bore of the master cylinder. On 30, 31 and 32 series, remove the push-rod.
  3. Remove the piston primary cup, spring and residual check valve from bore of master cylinder.
  4. On Moraine power and standard master cylinder, remove the rubber valve seat washer from cylinder bore with a wire hook.
  5. Power brake - remove filter from flange of master cylinder.
  6. On 30, 31 and 32 series power brake master cylinder, remove the bleeder valve.

CLEANING AND INSPECTION

  1. Wash all parts in brake flushing fluid and blow out all passages with compressed air. Be sure compensating port is open.
  2. Inspect cups, residual check valve, valve seat washer and secondary seal for a swelling or distorted condition. Replace if damaged. If such a condition exists, the entire system should be flushed (See FLUSHING HYDRAULIC SYSTEM) and all rubber parts in the wheel cylinders replaced.

CAUTION

Do not attempt to hone the master cylinder bore as a means of salvaging the cylinder assembly. Reconditioning of the bore leaves the walls sufficiently rough to cause premature failure of the rubber cups. It also enlarges the bore to the extent that the standard size piston and seals will not fit properly.

Assembly (Figs. 11-11 & 11-12)

  1. Lubricate master cylinder bore and all rubber parts with Brake Fluid Super No. 11.
  2. Install check valve rubber washer against the shoulder inside the master cylinder bore.
  3. Install large end of spring over residual check valve, then install the assembly into the bore (check valve end first).
  4. Install primary cup over end of spring (dish side toward spring).
  5. On all except 30, 31 and 32 series (manual brake) install piston into bore and while compressing spring, install retaining ring.
  6. On 30, 31 and 32 manual brake series install piston and push-rod and while compressing spring, install retaining ring.
  7. Standard brake - install boot over lip of master cylinder casting.
  8. On 30, 31 and 32 series power brake master cylinder, install bleeder valve.

Fig. 11-12 Master Cylinder (Bendix)