Power Brake Booster Explanation

POWER BRAKE BOOSTER DESCRIPTION
The booster assembly consists of a housing divided into separate chambers by two internal diaphragms. The outer edge of each diaphragm is attached to the booster housing.

Two push rods are used in the booster. The primary push rod connects the booster to the brake pedal. The secondary push rod connects the booster to the master cylinder to stroke the cylinder pistons.
POWER BRAKE BOOSTER OPERATION
The atmospheric inlet valve is opened and closed by the primary push rod. Booster vacuum supply is through a hose attached to an intake manifold fitting at one end and to the booster check valve at the other. The vacuum check valve in the booster housing is a one-way device that prevents vacuum leak back.

Power assist is generated by utilizing the pressure differential between normal atmospheric pressure and a vacuum. The vacuum needed for booster operation is taken directly from the engine intake manifold. The entry point for atmospheric pressure is through a filter and inlet valve at the rear of the housing

The chamber areas forward of the booster diaphragms are exposed to vacuum from the intake manifold. The chamber areas to the rear of the diaphragms, are exposed to normal atmospheric pressure of 101.3 kilopascals (14.7 pounds/square in.).

Brake pedal application causes the primary push rod to open the atmospheric inlet valve. This exposes the area behind the diaphragms to atmospheric pressure. The resulting pressure differential provides the extra apply force for power assist.

The booster check valve, check valve grommet and booster seals are serviceable.

POWER BRAKE BOOSTER REMOVAL
NOTE: LHD shown in graphics. The removal and installation procedures and torques specs are the same for the RHD.

1. Remove the master cylinder.
2. Disconnect vacuum hose from booster check valve.
3. Remove retaining clip that secures booster push rod to brake pedal and slide the rod off the pin.
4. Remove the nuts (Fig 2) #1 attaching booster mounting plate to the front cowl panel.
5. In engine compartment, slide booster and mounting plate out of the cowl panel and remove the booster assembly from engine compartment.
6. Remove booster mounting nuts (Fig 3) #2 from the mounting plate #1.
7. Disconnect the clutch pedal from the clutch M/C if equipped.
8. Remove the booster from the mounting plate (Fig 3) #1.

POWER BRAKE BOOSTER INSTALLATION
NOTE: LHD shown in graphics. The removal and installation procedures and torques specs are the same for the RHD.
1. Clean the booster mounting surface.
2. Install the booster on the mounting plate (Fig 3) #1.
3. Install the booster mounting nuts (Fig 3) #2 that attach booster to mounting plate. Tighten booster mounting nuts to 25 N.m (18 ft. lbs.).
4. Install the booster assembly (Fig 2) #2 with the mounting plate to the front cowl.
5. Install the booster mounting plate nuts (Fig 2) #1 that attach the mounting plate to the front cowl.
Tighten booster mounting plate nuts in an X pattern to 18 N.m (159 in. lbs.).
6. Connect vacuum hose to booster check valve.
7. Install master cylinder.
8. Lubricate the pedal pin and bushing with Mopar multi-mileage grease. Then slide the booster push rod onto brake pedal pin and secure with retaining clip.
9. Reconnect the clutch M/C to pedal if equipped.
10. Top off master cylinder fluid level and bleed base brakes.