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2-9
PART 2 - 2 - Brake System
Section
Page
1 Description and Operation
2-9
Dual-Master Cylinder Brake System
2-9
Disc Brakes
2-10
Hydraulic Self-Adjusting
Brake System
2-12
Booster System
2-14
Parking Brake
2-14
2 In-Vehicle Adjustments and Repairs
2-15
Brake Shoe Adjustments
2-15
Front Brake Drum
2-16
Rear Brake Drum
2-16
Brake Shoes and Adjusting Screw
2-16
Disc Brake Shoe and Lining
Replacement
2-17
Disc Brake Caliper Assembly
2-20
Front Wheel Hub and Rotor Assembly-
Disc Brakes
2-20
Disc Brake Rotor Splash Shield
2-20
Proportioning Valve
2-20
Standard or Rear Wheel Cylinder
Repair
2-21
Wheel Cylinder Replacement
2-21
Section
Page
Backing Plate Replacement
2-21
Hydraulic Lines
2-23
3 Removal and Installation
2-23
Dual-Master Cylinder-
Standard Brakes
2-23
Dual-Master Cylinder-
Power Brakes
2-24
Pressure Differential Valve
2-24
Booster Unit
2-25
Brake Pedal—Manual Shift
Transmission
2-25
Brake Pedal—Automatic Transmission
2-26
Parking Brake Control Assembly
2-26
Parking Brake to Equalizer Cable
2-26
Parking Brake Equalizer to
Rear Wheel Cable
2-26
4 Major Repair Operations
2-28
Brake Drum Refinishing
2-28
Rotor Refinishing
2-28
Brake Shoe Relining
2-28
Dual-Master Cylinder
2-28
Disc Brake Caliper
2-29
1
DESCRIPTION AND OPERATION
Disc brakes are available as op-
tional equipment for the front wheels.
The dual-master cylinder equipped
hydraulic brake system employs sin-
gle anchor, internal expanding and
self-adjusting drum brake assemblies
on the rear wheels of vehicles with disc
brakes, and on the front and rear
wheels of all others.
A vacuum booster is available as
optional equipment.
DUAL MASTER CYLINDER
BRAKE SYSTEM
The dual-master cylinder brake
system has been incorporated in all
models to provide increased safety.
The system consists of a dual-master
cylinder, pressure differential valve
assembly and a switch. The switch
on the differential valve activates a
dual-brake warning light, located on
the instrument panel.
The dual-master cylinder brake
system is similar to a conventional
(single) system, two master cylinders
are combined in a singal cast iron
casting (Fig. 1). One portion actuates
the primary (front) brake system and
the other actuates the secondary
(rear) brake system (Figs. 20 and 22).
Hydraulic fluid leakage or failure of
one of the systems does not impair
the operation of the other portion of
the dual-brake system. A dual-brake
warning light signals a failure of
either the front (primary) or rear
(secondary) brake system.
On power disc equipped vehicles,
the dual-master cylinder has the mas-
ter cylinder outlet port for the rear
(secondary) brake system located on
the bottom of the master cylinder
body. A master cylinder hydraulic
system bleed screw is located in the
outboard side of the master cylinder
casting. The front (primary) brake
system outlet port is located on the
outboard side of the master cylinder.
On power drum and standard drum
equipped vehicles, the rear (secon-
dary) and front (primary) brake sys-
tem outlet ports are located on the
outboard side of the master cylinder
casting. A bleed screw is not used on
the master cylinder for power drum
and standard drum equipped vehicles.
A code letter is stamped on the
end of the master cylinder body cast-
ing for easy service identification.
Code letter A or P identifies the
power disc brake master cylinder,
code letter T identifies the standard
drum brake master cylinder.
A brake pressure differential valve
assembly (Fig. 2) incorporating a
hydraulically
operated
mechanical
switch is utilized to operate a dual-
brake warning light, located on the
instrument panel.
Brake tubes are connected from the
dual-master cylinder front (primary)
and rear (secondary) brake systems
to the pressure differential valve (Fig.
2).
The pressure differential valve is
mounted vertically on the frame side
rail within the engine compartment.
The primary (front) brake system
outlet tubes are connected to the
ports located in the upper side of the
differential vavle assembly and the
secondary (rear) brake system outlet
tubes are connected to the ports lo-
cated in the lower side of the dif-
ferential valve assembly.
Hydraulic pressure for both rear
wheel brakes is provided from the
single secondary (rear) brake outlet
line, located opposite the secondary
system inlet port of the differential
valve. On disc brake equipped vehi-
cles, a proportioning valve is included
in the system and is connected to
the differential valve through inlet
and outlet tubes. The brake hose
bracket serves as a junction point for
the individual brake lines that lead
to the wheel cylinders of right and
left rear brake components.
When the brake pedal is depressed,
both the primary (front brake) and
secondary (rear brake) master cylin-
der pistons are moved simultaneously
to exert hydraulic fluid pressure on
their independent hydraulic system.
The fluid displacement of the dual-
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