|Home||Diplomat Info||Registry||Upgrades||Photos||Links||Farley||Site Tools||Manual||Forum|
The body of the two piece master cylinder (Fig. 1), is made of aluminum and the reservoir is made of nylon.
The two compartments of the reservoir are interconnected to permit equalization of the fluid level.
However, a sufficient quantity of fluid is retained in the reservoir of the unaffected system to permit operation of that half of the master cylinder even if the other half of the reservoir is drained due to a hydraulic leak.
When servicing the aluminum master cylinder:
a. Use extra care not to cross threads when installing brake line tubing to master cylinder, tighten tube fittings to specifications only.
b. The surface of the master cylinder bore is anodized to increase durability and prevent pitting and corrosion. Since honing the bore would remove this coating, aluminum master cylinders should never be honed when being rebuilt. If the anodized coating shows sufficient wear to expose the aluminum surface, replace the master cylinder.
c. The secondary prison does not use an �0� ring seal like the older cast iron ones, also do not use cast iron master cylinder secondary pistons or springs in aluminum master cylinders.
d. The reservoir is keyed to prevent installation in the wrong direction or the use of the wrong reservoir. The cap diaphragms are of a controlled venting design and have a precision slit in each to allow pressure to equalize if required.
The forwardmost outlet tube from the master cylinder is connected to the hydraulic system control valve and then to the rear brakes. This system is referred to as the secondary. The rearmost outlet tube from the master cylinder is connected to the control valve and the front brakes. This system is referred to as primary.
No residual pressure valves are used in master cylinder outlets. During master cylinder bleeding, residual valves should be installed on the outlet ends of both bleeder tubes.
The fluid level in the master cylinder should be checked twice a year. The nylon reservoirs are marked with the words �fill to bottom of rings� indicating proper fluid level. If adding fluid is necessary, before removing the reservoir caps, wipe caps and reservoir clean to prevent dirt and other foreign matter from dropping into the reservoir. If necessary, add fluid to bring level to bottom of rings in reservoir. With disc brakes, fluid level can be expected to fall as the brake pads wear. Only brake fluid conforming to DOT 3 should be used. MOPAR Brake Fluid is a fluid of this quality and is recommended to provide best brake performance. Use of a brake fluid that may have a lower initial boiling point, such as fluid identified as 70R1 or unidentified as to specification may result in sudden brake failure during hard prolonged braking. Use only brake fluid that has been stored in a tightly closed container, to avoid contamination or moisture.
CAUTION: Do not allow petroleum base fluid to contaminate the brake fluid. Seal damage will result.
MASTER CYLINDER REMOVAL
(1) Disconnect primary and secondary brake tubes from master cylinder. Install plugs in the outlets of master cylinder.
(2) Remove nuts that attach master cylinder to power brake unit.
(3) Slide master cylinder straight out away from power brake unit.
Before disassembling the master cylinder (Fig. 1) clean outside of reservoir and master cylinder housing.
(1) Remove reservoir caps and empty the brake fluid from reservoir.
(2) Position master cylinder in a vise. Grasp reservoir and firmly rock from side to side to remove from master cylinder housing (Fig. 2).
(3) Remove and discard master cylinder housing to reservoir grommets.
(4) Install new housing to reservoir grommets into master cylinder housing.
(5) Lubricate reservoir mounting area with clean brake fluid. Place reservoir in position over grommets and using a rocking motion, seat reservoir properly onto master cylinder housing. CAUTION: Be sure that reservoir is positioned properly! All lettering should be properly read from the left side of the master cylinder. Be sure reservoir seats all the way down until the bottom of the reservoir touches the top of the grommet.
BLEEDING MASTER CYLINDER
Before installing the master cylinder on vehicle, it must be bled on the bench as follows:
(1) Clamp master cylinder in a vise and attach bleeding tubes Tool C-4029.
Complete bleeding will require a residual valve on outlet of each bleeder tube. Tool C-4029 is equipped with one residual valve on primary outlet tube. To modify secondary outlet tube use flaring tool C-4047 to flare tube outlet and install residual valve SP-51 95.
(2) Fill both reservoirs with approved brake fluid.
(3) Using a brass rod or wood dowel depress push rod slowly and allow the pistons to return under pressure of springs. Do this several times until all air bubbles are expelled (Fig. 3).
(4) Remove bleeding tubes from cylinder, plug outlets to prevent spillage and install caps.
(5) Remove from vise and install master cylinder on vehicle.
INSTALLING MASTER CYLINDER
(1) Position master cylinder over studs of power brake unit, aligning power brake push rod with
master cylinder piston.
(2) Install and tighten attaching nuts to 200 � 30 in. lbs. (22.59 � 3.38 N�m).
(3) Connect front and rear brake tubes and tighten to 170 in. lbs. (19 N�m).
(4) Bleed brakes using normal procedure, being sure fluid level in master cylinder is maintained. (See Bleeding the Brake System in �Service Adjustments�.)