ISUZU AXIOM 2002 Service Repair Manual

5C±21 POWER±ASSISTED BRAKE SYSTEM
Fluid Reservoir Tank
Fluid Reservoir Tank and Associated Parts
330RW003
Legend
(1) Fluid Reservoir
(2) Electrical Connector(3) O±ring
(4) Retainer
Removal
NOTE: Before removing the fluid reservoir, remove the
brake fluid from the fluid reservoir.
1. Disconnect electrical connector.
2. Remove retainer (1).
330RW004
3. Remove fluid reservoir and the fluid level sensor built
into the fluid reservoir. The fluid level sensor cannot
be removed for servicing.
4. Remove O±ring.
Installation
To install, follow the removal steps in the reverse order,
noting the following points:
1. O±ring (1) must be set onto the fluid reservoir (2),
before installing fluid reservoir.
330RW005

5C±22
POWER±ASSISTED BRAKE SYSTEM
Master Cylinder Assembly
Master Cylinder Assembly and Associated Parts
330RW010
Legend
(1) Electrical Connector
(2) Master Cylinder
(3) 2 attaching Nuts(4) P&B Valve and Bracket
(5) Brake Pipes
(6) Spacer and 2 gaskets
Removal
CAUTION: When removing the master cylinder from
the vacuum booster, be sure to get rid of the internal
negative pressure of the vacuum booster (by, for
instance, disconnecting the vacuum hose) in
advance.
If any negative pressure remains in the vacuum
booster, the piston may possibly come out when the
master cylinder is being removed, letting the brake
fluid run out.
While removing the 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.
1. Disconnect electrical connector.
2. Remove brake pipes and after disconnecting the
brake pipe, cap or tape the openings of the brake pipe
to prevent the entry of foreign matter.
3. Remove 2 attaching nuts.
4. Remove P&B valve and bracket.5. Remove master cylinder.
6. Remove spacer and the 2 gaskets.
Inspection and Repair
Master Cylinder
The master cylinder is not repairable and must be
replaced as a complete assembly if found defective.
Inspection
Excessive brake pedal travel, malfunction or dragging
brake suggests that the master cylinder is defective. In
such cases perform the following visual check:
Visual Check
Make parts replacement as required if wear, distortion,
nicks, cuts, corrosion, or other abnormal conditions are
found through the following parts inspection:

Master cylinder body

Fluid reservoir

O±ring

5C±23 POWER±ASSISTED BRAKE SYSTEM
Functional Inspection of Master Cylinder
Piston
Push the primary piston (1) with your fingers to check that
it travels smoothly. If the motion is questionable, replace
the master cylinder as a complete assembly.
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Functional Inspection of Master Cylinder
Inspect the master cylinder for functionality described
below. Replace if necessary.
Install the primary piston holder (3) J±39242 (including
the master cylinder attachment (5) and master cylinder
plug (7)) onto the master cylinder (4). Make sure the
spacer (2) (2 bolts) with its adjusting bolt is screwed in up
to the ª0º line
330RW008Connect the master cylinder attachment (5) J±39242 with
the end of the radiator cap tester (6) J±24460±01, and
apply air pressure with the cap tester. Make sure there is
no rise in pressure while adjusting the bolt to the ª5º line.
There should be a pressure increase of 0.5 kg/cm
2 or
more.
330RW009
NOTE: When checking the front (or primary) side, be
sure to mount the master cylinder plug in the rear (or
secondary) port.
ª0º Lineª5º Line
Apply air
pressure to the
front and rear
portsNo pressure
rise.Pressure
increase of 0.5
kg/cm
2 or more
RemarksChecks port
into the
atmospheric
pressure
chamberChecks air
tightness of the
pressure cham-
ber
NOTE:
1. Do not use an air compressor, as the air from the
compressor is mixed with compressor oil.
2. When installing the master cylinder onto the vacuum
booster, always adjust the vacuum booster push rod.
(Refer to
Vacuum Booster in this section).
3. After the master cylinder is installed onto the vehicle,
check for leakage, pedal travel and pedal free play.
Installation
1. Install spacer and the 2 gaskets.
2. Install master cylinder.
When replacing the master cylinder or vacuum
booster or both, always measure the vacuum booster
push rod protrusion and adjust it as necessary (Refer
to
Vacuum Booster in section).
3. Install P&B valve and bracket.
4. Install 2 attaching nuts and tighten the attaching nuts
to the specified torque.
Torque: 13 N´m (113 lb in)

5C±24
POWER±ASSISTED BRAKE SYSTEM
5. Install brake pipes and tighten the brake pipe to the
specified torque.
Master cylinder and P&B valve sides
Torque: 15 N´m (11 lb ft)
Others
Torque: 16 N´m (12 lb ft)
6. Connect electrical connector.
Main Data and Specifications
General Specifications
TypeDual±circuit
Piston bore
diameter25.4 mm (1.000 in)
Torque Specifications
E05R200002
Special Tools
ILLUSTRATIONTOOL NO.
TOOL NAME
J-39242
Primary Piston Holder
(including master
cylinder attachment and
master cylinder plug
J-24460-01
Radiator Cap Tester

5C±25 POWER±ASSISTED BRAKE SYSTEM
Vacuum Booster Assembly
Vacuum Booster Assembly and Associated Parts
331RW005
Legend
(1) Pin
(2) Vacuum Booster Fixing Nut
(3) Vacuum Hose(4) Master Cylinder
(5) Vacuum Booster
(6) Snap Pin
Removal
1. Before removing the vacuum booster assembly,
disconnect and remove the brake pipes.
2. Remove master cylinder, refer to
Master Cylinder
Removal
in this section.
CAUTION: When removing the master cylinder from
the vacuum booster, be sure to get rid of the internal
negative pressure of the vacuum booster (by, for
instance, disconnecting the vacuum hose) in
advance.
If any negative pressure remains in the vacuum
booster, the piston may possibly come out when the
master cylinder is being removed, letting the brake
fluid run out.
Do not hold the piston while removing the master cy-
liner, the piston 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.
3. Remove vacuum hose.4. Disconnect the yoke clevis from the brake pedal.
5. Remove vacuum booster fixing nut.
6. Remove vacuum booster.

5C±26
POWER±ASSISTED BRAKE SYSTEM
Inspection and Repair
Vacuum Hose (The built in check valve)
1. Inspect the check valve (2), which is installed inside
the vacuum hose.
2. Air should pass freely from the vacuum booster (3) to
the engine (1).
3. Air should not pass from the engine (1) to the vacuum
booster (3). If it does, the check valve is inoperative
and the vacuum hose built in the check valve must be
replaced.
360RY00004
Installation
1. Perform vacuum booster and vacuum booster push
rod adjustment.
NOTE: When replacing either the master cylinder or
vacuum booster, be sure to measure push rod, and adjust
if required.
2. Remove retainer from vacuum booster front shell
using a small screwdriver. Then gently draw plate and
seal assembly out of the shell inside.
331RS003
3. Set push rod gauge J±39216 on vacuum booster, and
apply negative pressure by means of vacuum pump
J±23738±A so that the pressure in the vacuum
booster becomes 500 mm Hg.
NOTE: Be s u r e t o apply NEGATIVE pressure after
installing a push rod gauge on the vacuum booster.
331RS004

5C±27 POWER±ASSISTED BRAKE SYSTEM
4. Measure dimension (4).
Dimension (4) (Standard): ±0.1±0.1 mm
(±0.0039±0.0039 in)
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5. If dimension (4) is out of the standard range, adjust
push rod using the Push Rod Support J±39241.
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6. Mount plate and seal assembly in vacuum booster
front shell. Then install the retainer.
7. Install vacuum booster fixing nut and tighten the
specified torque.
Torque: 15 N´m (11 lb ft)
8. Install yoke clevis.
9. Connect vacuum hose and make sure that the arrow
on the hose points in the direction of the engine.
10. Install master cylinder, refer to
Master Cylinder
Installation
in this section.

5C±28
POWER±ASSISTED BRAKE SYSTEM
Exterior Components
Exterior Components and Associated Parts
331RW006
Legend
(1) Yoke Clevis
(2) Lock Nut
(3) Retaining Clip
(4) Valve Body Guard
(5) Silencer(6) Filter
(7) 2 Gaskets and Spacer
(8) Vacuum Booster
(9) Retainer
(10) Plate and Seal Assembly
(11) Master Cylinder
Removal
1. Remove master cylinder. Refer to Master Cylinder in
this section.
2. Remove vacuum booster. Refer to
Vacuum Booster
in this section.
3. Remove yoke clevis.
4. Remove lock nut.
5. Remove retaining clip.
6. Remove valve body guard.
7. Remove silencer.
8. Remove filter.
9. Remove 2 gaskets and spacer.
10. Remove retainer, using a small screwdriver to pry out
the retainer. Gently pull out the plate and seal
assembly from the shell.
331RS003

5C±29 POWER±ASSISTED BRAKE SYSTEM
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
Installation
1. Install plate and seal assembly.
2. Install retainer.3. Install 2 gaskets and spacer.
4. Install filter.
5. Install silencer.
6. Install valve body guard.
7. Install retainer.
8. Install lock nut and yoke clevis and tighten to the
specified torque.
Torque: 20 N´m (15 lb ft)
9. Install vacuum booster, refer to
Vacuum Booster in
this section.
10. Install master cylinder, refer to
Master Cylinder in this
section and after installation, perform brake pedal
check and adjustment. Refer to
Brake Pedal in this
section.
Vacuum Booster Overhaul
Vacuum Booster
The vacuum booster cannot be disassembled for repair.
Replace a defective vacuum booster with a new one.

5C±30
POWER±ASSISTED BRAKE SYSTEM
Main Data and Specifications
General Specifications
Vacuum booster diaphragm diameter (Front)205 mm (8.07 in)
Vacuum booster diaphragm diameter (Rear)230 mm (9.06 in)
Push rod strokeMore than 32.0 mm (1.26 in)
Plunger diameter10.25 mm (0.40 in)
Push rod diameter27.4 mm (1.08 in)
Torque Specifications
330R200001