ISUZU TROOPER 1995 Workshop Manual

HYDRAULIC BRAKES 5A-21
MAIN DATA AND SPECIFICATIONS
GENERAL SPECIFICATIONS
Brake pedal
Pedal
free play
Pedal
height
Parking brake
Type Brake
handle(stem) travel
Master cylinder
Type
Piston bore diameter
TORQUE SPECIFICATIONS
mm (in)
mm (in)
mm (in)
13 (1131b·in)
Fig. 5A-23 6
to 10 (0.23 to 0.39)
208 to 218
(8.19 to 8.58)
Duo-servo
6 to 7 notches
When
pulled with a force of 30 kg (66 lb)
Dual-circuit
25.4 (1.000)
4-Wheel Antilock Brake System
N·m {lb·ft}
-Brake fluid pipe line -Flexible hose
Rear Wheel Antilock Brake System
-Brake fluid pipe line -Flexible hose

SA-22 HYDRAULIC BRAKES
SPECIAL TOOLS
ILLUSTRATION TOOL
NO.
TOOL NAME ILLUSTRATION TOOL
NO.
TOOL NAME
~
J-39242
Primary piston holder
(including master cylinder attachment ~(i and master cylinder plug) ~t
J-24460-01
Radiator cap tester
•

BRAKE BOOSTER SYSTEM 5A 1-1
SECTION 5A1
BRAKE BOOSTER SYSTEM
W CAUTION:
• Fasteners are an important attaching part in that they could affect performance of vital parts and systems,
and/or could result in major repair expense. They must be replaced with one of the same part number or with
an equivalent part if replacement becomes necessary. Do not use replacement parts of lesser quality or
substitute design. Torque values must be used as specified during reassembly to assure proper retention of
these parts.
CONTENTS
General Description . . . . . . . . . . . . . . . . . . . SA 1-1 Vacuum Booster .................... SA1-6
Diagnosis ..................... See Section SA Main Data and Specifications ........... SA1-6
On-Vehicle Service ................... SA1-2 General Specifications ............... SA1-6
Vacuum Booster Assembly ........... SA1-2 Torque Specifications ................ SA1-6
Exterior Components ................ SA1-4 Special Tools ......................... SA1-7
Unit Repair .......................... SA1-6
GENERAL DESCRIPTION
This booster is a tandem vacuum unit with a
diaphragm effective diameter
205 mm + 230 mm. In
normal operating mode, with the service brakes in the
released position, the tandem vacuum booster
operates
with vacuum on both sides of its diaphragms.
When the brakes are
applied, air at atmospheric
pressure is admitted
to one side of each diaphragm to
provide the power assist. When the service brake is
released, the atmospheric air is shut off from the one
side
of each diaphragm. The air is then drawn from the
booster through the vacuum check
valve to the
vacuum source.
W CAUTION:
• If any hydraulic component IS removed or
disconnected, it may be necessary to bleed all
or part of the brake system.
Fig.
5A1-1
• The torque values specified are for dry,
unlubricated fasteners.
• The vacuum booster is not repairable and must
be replaced as complete assembly.

SA 1-2 BRAKE BOOSTER SYSTEM
ON-VEHICLE SERVICE
VACUUM BOOSTER ASSEMBLY
4
7
'
I ,
l_
Removal Steps 1. Master cylinder
2. Vacuum hose
3. Yoke clevis 4. Vacuum booster fixing nut 5. Vacuum booster
Installation steps
To install, follow the removal steps in the reverse order
®I
®'
Fig. 5A1-2
1••1 REMOVAL
• Before removing the vacuum booster
assembly, disconnect and remove brake pipes.
1. Master cylinder
• Refer to "Master Cylinder Removal" in Section
5A.
'\fCAUTION:
When removing master cylinder from vacuum
booster, be sure to get rid
of the internal negative
pressure
of the vaccum booster (by, for instance,
disconnecting vaccum hose) in advance.
If any negative pressure remains in the vaccum
booster, the piston may
possibly come out when
the master cylinder is being removed, letting the
brake
fluid run out.
While removing master cylinder, further, do not
hold the piston as it can be easily pulled out.
Outside surface of the piston is the surface on
which
seals are to slide. Care should be taken to
keep the surface free of cuts and dents.
2. Vacuum hose
3. Yoke clevis
• Disconnect the yoke clevis from the brake
pedal.
4. Vacuum booster fixing nut
5. Vacuum booster
Fig. 5A1-3
~ INSPECTION AND REPAIR
Vacuum hose (Fig. 5A1-3)
Inspect the check valve, which is installed inside
the vacuum hose.
• Air should pass freely from the vacuum booster
to the engine.
• Air should not pass from the engine to the
vacuum booster.
If it does, the check valve is
inoperative and
must be replaced.
•

l·u·IINSTALLATION
5. Vacuum booster
I~EI Vacuum booster push rod adjustment
NOTE:
When replacing either master cylinder or vacuum
booster, be sure
to measure push rod, and adjust if
required.
~ Push rod gauge : J-39216
~ Vacuum pump : J-23738-A
Push rod
support: J-39241
• Remove retainer from vacuum booster front
shell using a small screwdriver. Then gently
draw plate and seal assembly out of the shell
inside (Fig. 5A1-4).
Fig.
5A1-4
• Set push rod gauge on vacuum booster, and
apply negative pressure by means of vacuum
pump so that the pressure in the vacuum
booster becomes
500 mm Hg. (Fig. 5A1-5).
NOTE:
Be sure to apply NEGATIVE pressure after
installing a push rod gauge on vacuum booster.
J-39216
Fig. 5A1-5
BRAKE BOOSTER SYSTEM 5A1-3
Fig. 5A1-6
• Measure dimension (b) (Fig. 5A 1-6)
~~~ Dimension (b) (Standard) mm I 0 ± 0.1
• If dimension (b) is out of the standard range,
adjust push rod using the
special tool (Fig. 5A 1-
7).
T·wrench
J-39241
Fig. 5A1-7
• Mount plate and seal assembly in vacuum
booster
front shell. Then install retainer.
4. Vacuum booster fixing nut
I~I ____ T_o_rq_u_e _______ N_·m __ (l_b·_ft_) __ ~_2_1_(_16_)_
3. Yoke clevis
2. Vacuum hose
• Make sure that the arrow on the hose points in
the direction
of the engine.
1.
Master cylinder
• Refer to "Master Cylinder Installation" in
Section 5A.

SA 1-4 EXTERI _ BRAKE BOOSTER SYSTEM OR COMPQ .• N,.=E~N~T_s ____ _
l;JJ!!
3 4 5 6 7
8 9
Removal steps. d
1 Master cylm er
2. Vacuum b.ooster
3. Yoke
clevis
4
: Lock n.ut .
5
Retainmg clip d
6: Valve body guar
7. Silencer
8. filter d spacer
9. 2 gas.kets an
10.
Retame~ seal assembly 11. Plate an
Installation s:~P.; the removal To install, fo o rse order. ·In the reve
steps
DREMOVAL
-----------FF:iigg. SA1-8-
1::1 1 • in
Section 1. Master cyl!.~::ter Cylinder Remova • Refer to
SA. t r I" in this
2 Vacuu "Vacuum m boos e Booster Remova · • Refer to
section.
Yoke
clevis 3. t Lock nu .
4. Retaining clop d
5. Valve body guar 6.
Silencer 7.
a. Filter d spacer
9 2 gaskets an tthe retainer.
1 0. Retainer a II screwdriver tol'::'a~~ssembly from • Use a sm II outthe plate an s Gently pu F' SA 1-9). the shell ( IQ.
11. Fig.
SA1-9
I assembly Plate and sea
•

[1!) INSPECTION AND REPAIR
Visual check:
'-"' Make necessary parts replacement if cuts, nicks,
excessive wear,
or other abnormal conditions are
found through inspection.
Check the following parts.
• Yoke clevis
• Valve
body guard
• Silencer
• Filter
• Plate
and seal assembly.
I••IINSTALLATION
11. Plate and seal assembly
1 0. Retainer
9. 2 gaskets and spacer
8. Filter
7. Silencer
6. Valve body guard
5. Retainer
4. Lock nut
20 (15) 1~1 Torque N·m (lb·ft) ----------1....---
3. Yoke clevis
2. Vacuum booster
• Refer to "Vacuum Booster Installation" in this
section.
'-"" 1. Master cylinder
• Refer to "Master Cylinder Installation" in
Section 5A.
• After installation, perform brake pedal check
and adjustment. Refer
to "Brake Pedal
Assembly" in Section 5A.
BRAKE BOOSTER SYSTEM 5A 1-5

5A 1-6 BRAKE BOOSTER SYSTEM
UNIT REPAIR
VACUUM BOOSTER
• The vacuum booster cannot be disassembled
for repair. Replace a defective vacuum booster
with a new one.
MAIN DATA AND SPECIFICATIONS
GENERAL SPECIFICATIONS
Vacuum booster diaphragm diameter
Front
Rear
Push rod stroke
Plunger diameter
Push rod diameter
TORQUE SPECIFICATIONS
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
13 (1131b·in)
Fig. 5A1-10
205 (8.07)
230 (9.06)
More than 32.0 (1.26)
10.25 (0.40)
27.4 (1.08)
N·m (lb·ft)
.............................................. ----------------------------------~ .

BRAKE BOOSTER SYSTEM 5A 1-7
SPECIAL TOOLS
ILLUSTRATION TOOL NO.
TOOL
NAME
0
J-39216
Push rod gauge
~
J-23738-A
Vacuum pump
r
J-39241
Push rod support

MEMO
•