Ford Thunderbird 1967 - Part 2-2: Brake System

2-8
PART
2-2-Brake
System
Section
Page
1
Description and
Operation
2-8
Dual-Master
Cylinder Brake
System
2-8
Disc
Brake
Assemblies
-
Front Wheels
2-10
Self
Adjusting
Brake
Assemblies
Rear
Wheels
2-11
Booster
System 2-12
Parking
Brakes
2-12
2 In-Car
Adjustments
and Repairs 2-12
Front
(Disc)
Brake
Shoe
and
Lining
Replacement
2-12
Disc Brake Caliper
Assembly
2-13
Front
Wheel Hub and Rotor
Assembly
2-14
Disc Brake Rotor Splash Shield
2-14
Proportioning
Valve
2-14
Brake
Shoe
Adjustments
Rear
Wheels
2-14
Rear Brake
Drum 2-14
Rear
Brake Shoe
Replacement
2-15
Rear
Wheel
Cylinder Repair
2-16
Rear
Wheel
Cylinder Replacement
2-16
Rear Brake
Backing
Plate
Replacement
2-17
Hydraulic Lines
2-17
Brake
Hose
Replacement
2-17
Removal
and Installation
2-19
Dual-Master
Cylinder
Power Brakes
2-19
Pressure Differential Valve
Assembly
2-19
Brake Booster
2-20
Brake
Pedal
2-20
Parking
Brake
Control
Assembly
2-20
Parking
Brake
Vacuum Power
Unit
2-21
Parking
Brake
Actuator-To-Control
Assembly
Cable
2-2
1
Parking
Brake
Equalizer-To-Rear
Wheel
Cable
2-21
Parking
Brake
Actuator-To-Equalizer
Cable
2-21
Major Repair Operations
2-23
Brake Drum
Refinishing
2-23
Rotor
Refinishing
2-23
Rear Brake
Shoe
Relining
2-23
Dual-Master Cylinder
2-23
Disc Brake
Caliper
2-24
DESCRIPTION
AND
OPERATION
The
brake system employs
disc
brakes
on the
front
wheels
and
single
anchor,
internal
expanding
and
self-
adjusting
brake assemblies on
the
rear
wheels. The system is powered
by
a
dual-master
cylinder and
a
booster as
standard
equipment.
DUAL-MASTER
CYLINDER
BRAKE
SYSTEM
The dual-master
cylinder
brake
system has
been
incorporated
in all
vehicle
models
to provide increased
ve
hicle
safety. The
system consists
of a
dual-master
cylinder,
pressure
differ
ential valve
assembly
and a
switch.
The switch
on
the differential
valve
act
ivates a dual-brake
warning
light,
located on the instrument
panel.
The
dual-master
cylinder brake
system
is similar
to
a conventional
(single)
brake
master cylinder
system.
In the
dual-system,
two
master
cylin
ders are
combined in
a single
cast
iron
casting
(Fig. 1). One portion act
uates
the
primary
(front)
brake system
and the
other actuates
the
secondary
(rear)
brake
system (Fig.
1).
Hydrau
lic
fluid
leakage
or failure of
one of
the
systems
does not
impair
the
opera
tion
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.
The
dual-master
cylinder has
the
master
cylinder
outlet
ports
for the
rear
(secondary)
brake
system
located
on
the
bottom
of
the
master
cylinder body.
Master
cylinder
hydraulic
system
bleed
screws
are
located
in the
out
board side of the
master cylinder
casting.
The code
letter
A
is stamped on the
end
of
the
master cylinder
body
cast
ing
for
easy
service identification.
A brake pressure
differential
valve
assembly
(Fig.
2)
incorporating
a
hy-
draulically
operated mechanical switch
is utilized
to operate a
dual-brake
warning
light,
located on the
instru
ment panel
to
the right of the clock.
Brake tubes
are
connected
from
the
dual-master cylinder front
(primary)
and
rear
(secondary)
brake
systems
to
the
pressure
differential
valve.
The
pressure
differential valve
is
mounted
vertically
on the frame
side
rail.
The
primary
(front)
brake
sys
tem outlet
tubes
are
connected
to
the
ports located in the
upper
side of
the
differential
valve
assembly
and
the
secondary
(rear)
brake system
outlet
tubes are
connected
to the
ports
lo
cated in the lower
side of
the
differen
tial 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. A
proportioning
valve is
lo
cated in the
secondary
(rear)
brake
system line that
leads
to the brake
hose
bracket
on
the rear
axle
hous
ing. 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.
OPERATION
When
the brake pedal
is
depressed,
both the
primary
(front
brake)
and
secondary
(rear
brake)
master cylinder
pistons
are moved
simultaneously
to
exert hydraulic fluid
pressure
on their
independent
hydraulic
system. The
fluid
displacement of
the
dual-master
cylinders is proportioned
to fulfill the
requirements
of each of
the
two inde
pendent
hydraulic brake
systems
(Fig. I).
If a failure of the
rear
(secondary)
brake system should
occur,
initial
brake pedal
movement causes
the un
restricted
secondary
piston
to bottom
in the
master cylinder
bore.
Primary
piston
movement
displaces
hydraulic
fluid in
the
primary
section
of the
dual-master cylinder
to actuate
the
front
brake
system.
Should the
front
(primary)
brake
system
fail,
initial brake pedal
move
ment causes the unrestricted
primary
piston
to
botlom out against
the sec
ondary
piston.
Continued
downward
movement of
the
brake
pedal
moves
the
secondary
piston
to
displace
hy
draulic
fluid in the
rear
brake
system,
actuating
the
rear
brakes.
The increased
pedal
travel
and
the
increased pedal
effort
required
to
com
pensate
for
the
loss
of
the failed
portion of the
brake system
provides