2002 ISUZU AXIOM Brake fluid

5C±48
POWER±ASSISTED BRAKE SYSTEM
Rear Disc Brake Caliper Assembly (4y4 Model)
Rear Disc Brake Caliper Assembly and Associated Parts
306RW007
Legend
(1) Brake Flexible Hose
(2) Clip
(3) Lock Bolt(4) Support Bracket
(5) Guide Bolt
(6) Pad Assembly with Shim
(7) Caliper Assembly
Removal
1. Raise the vehicle and support with suitable safety
stands.
2. Remove wheel and tire assembly, refer to
Wheels
and Tires System
in Section 3E.
3. Remove the bolt and gaskets, then disconnect the
flexible hose from the caliper and after disconnecting
the flexible hose (1), cap or tape the openings to
prevent entry of foreign material.
306RW008
4. Since the brake fluid flows out from the connecting
coupler, place a drain pan under the vehicle.5. Remove lock bolt (3).
6. Remove guide bolt (2).
306RW009
7. Remove caliper assembly.
8. Remove support bracket with pad assembly and take
care not to damage the flexible brake hose when
removing the support bracket.
9. Remove pad assembly with shim and mark the lining
locations if they are to be reinstalled.
10. Remove clip.

5C±57 POWER±ASSISTED BRAKE SYSTEM
Machining The Drum
If a drum is to be machined, only enough metal should be
removed to obtain a true, smooth braking surface. If a
drum does not clean-up when machined to a maximum
diameter, it must be replaced. Removal of more metal willaffect dissipation of heat and may cause distortion of the
drum.
After refinishing, replace any drum that exceeds a
maximum inside diameter of 296.5 mm (11.673 in). Do
not use a brake drum that is not within the specification.
Maximum inside diameter: 296.5 mm (11.673 in)
Wheel Cylinder Assembly (4y2 Model)
Wheel Cylinder Assembly and Associated Parts
305RW003
Legend
(1) Brake Linings
(2) Wheel Cylinder(3) Bolts
(4) Brake Pipe
Removal
1. Remove brake linings (1).

Refer to
Brake Lining and Associated Parts in this
section.
2. Remove brake pipe (4).

Plug the opening in the line to prevent fluid loss and
contamination.
3. Remove bolts (3) and wheel cylinder (2).
Installation
1. Install wheel cylinder (2) and tighten bolts (3) to the
specified torque.
Torque: 10 N´m (8 lb ft)
2. Install brake pipe (4) and tighten the nut to the
specified torque.
Torque: 16 N´m (12 lb ft)
3. Install brake linings (1).

Refer to
Brake Lining Replacement in this section.

Bleed brake system. Refer to
Hydraulic Brake in
this section.

5C±61 POWER±ASSISTED BRAKE SYSTEM
AXIOM (Vehicles Produced After Aug./1/2001)
POWER-ASSISTED BRAKE SYSTEM
CONTENTS
Service Precaution 5C±62. . . . . . . . . . . . . . . . . . . . . .
General Description 5C±62. . . . . . . . . . . . . . . . . . . . .
Diagnosis 5C±66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Diagnosis 5C±67. . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Brakes 5C±70. . . . . . . . . . . . . . . . . . . . . . . .
Filling Master Cylinder Reservoir 5C±70. . . . . . . .
Deterioration of Brake Fluid 5C±70. . . . . . . . . . . . .
Leakage of Brake Fluid 5C±70. . . . . . . . . . . . . . . . .
Bleeding Brake Hydraulic System 5C±70. . . . . . . .
Flushing Brake Hydraulic System 5C±71. . . . . . . .
Brake Pipes and Hoses 5C±71. . . . . . . . . . . . . . . .
Brake Hose Inspection 5C±71. . . . . . . . . . . . . . . . .
Front Caliper Brake Hose 5C±72. . . . . . . . . . . . . . . .
Front Caliper Brake Hose and Associated
Parts 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Axle Brake Hose 5C±73. . . . . . . . . . . . . . . . . . .
Rear Axle Brake Hose and Associated
Parts 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Pipe 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . .
P & B (Proportioning and Bypass) Valve 5C±75. . . .
Removal 5C±75. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±75. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±76. . . . . . . . . . . . .
Brake Pedal 5C±77. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Pedal Height 5C±77. . . . . . . . . . . . . . . . .
Checking Pedal Travel 5C±77. . . . . . . . . . . . . . . . .
Brake Pedal and Associated Parts 5C±78. . . . . . .
Removal 5C±78. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±78. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stoplight Switch 5C±79. . . . . . . . . . . . . . . . . . . . . . . . .
Parts Location 5C±79. . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±79. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±79. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±80. . . . . . . . . . . . .
Master Cylinder Assembly 5C±81. . . . . . . . . . . . . . . .
Master Cylinder Assembly and Associated
Parts 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . Master Cylinder Assembly 5C±82. . . . . . . . . . . . . . . .
Master Cylinder Assembly Desassembled
View 5C±82. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Desassembly 5C±82. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 5C±82. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly 5C±83. . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±83. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±84. . . . . . . . . . .
Vacuum Booster Assembly 5C±85. . . . . . . . . . . . . . .
Vacuum Booster Assembly and Associated
Parts 5C±85. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±85. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±86. . . . . . . . . . . . . . . . . .
Exterior Components 5C±87. . . . . . . . . . . . . . . . . . . .
Exterior Components and Associated
Parts 5C±87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±87. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±88. . . . . . . . . . . . . . . . . .
Installation 5C±88. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vacuum Booster Overhaul 5C±88. . . . . . . . . . . . . . . .
Vacuum Booster 5C±88. . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±89. . . . . . . . . . . . .
Front Disc Brake Pads 5C±90. . . . . . . . . . . . . . . . . . .
Front Disc Brake Pads Inspection 5C±90. . . . . . . .
Front Disc Brake Pads and Associated
Parts 5C±90. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±91. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±91. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Disc Brake Rotor 5C±93. . . . . . . . . . . . . . . . . . .
Inspection 5C±93. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Brake Rotors 5C±93. . . . . . . . . . . . . . . .
Refinishing Brake Rotors 5C±93. . . . . . . . . . . . . . .
Front Disc Brake Caliper Assembly 5C±95. . . . . . . .
Front Disc Brake Caliper Assembly and
Associated Parts 5C±95. . . . . . . . . . . . . . . . . . . . . .
Removal 5C±95. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±96. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Disc Brake Caliper 5C±98. . . . . . . . . . . . . . . . .
Front Disc Brake Caliper Disassembled
View 5C±98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 5C±98. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±99. . . . . . . . . . . . . . . . . .
Reassembly 5C±99. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±100. . . . . . . . . . .
Rear Disc Brake Pads (4y4 Model) 5C±101. . . . . . . .

5C±63 POWER±ASSISTED BRAKE SYSTEM
The master cylinder contains two pistons that supply the
hydraulic pressure for a dual±circuit braking system. The
primary piston provides the fluid pressure to the front
brakes, while the secondary piston provides the fluid
pressure to the rear brakes. If the pressure is lost from
either system, the remaining system will function to stop
the vehicle.CAUTION:
1. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system. (Refer to
Bleeding Brake
Hydraulic System
in this section.)
2. The torque values specified are for dry,
unlubricated fasteners.
3. Perform service operations on a clean bench free
from all mineral oil materials.
Brake Booster
331R200001
This booster is a tandem vacuum unit with a diaphragm
effective diameter 205mm + 230mm (8.07in + 9.06in). 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 both sides of the diaphragm to provide the
power assist. When the service brake is released, the
atmospheric air is shut off from both sides of the
diaphram. The air is then drawn from the booster through
the vacuum check valve to the vacuum source.CAUTION:
1. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system.
2. The torque values specified are for dry,
unlubricated fasteners.
3. The vacuum booster is not repairable and must be
replaced as complete assembly.

5C±64
POWER±ASSISTED BRAKE SYSTEM
Disc Brake
Front Disc Brake
A05R200001
Rear Disc Brake (4y4 Model)
A05RW002
The disc brake assembly consists of a caliper, piston,
rotor, pad assembly and support bracket. The caliper
assembly has a fornt dual bore, rear single bore and is
mounted to the support bracket with two mounting bolts.
The support bracket allows the caliper to move laterally
against the rotor. The caliper is a one±piece casting with
the inboard side containing the piston bore. A square cut
rubber seal is located in a groove in the piston bore which
provides the hydraulic seal between the piston and the
cylinder wall.
NOTE:
1. Replace all components included in repair kits used to
service this caliper.
2. Lubricate rubber parts with clean brake fluid to ease
assembly.3. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or part
of the brake system.
4. Replace pads in axle sets only.
5. The torque values specified are for dry, unlubricated
fasteners.
6. Perform the service operation on a clean bench free
from all mineral oil materials.
Operation
Hydraulic pressure, created by applying the brake pedal,
is converted by the caliper to a stopping force. This force
creates a clamping action of the piston pressing towards
the rotors (outward) and the caliper slides inward toward
the vehicle. This clamping action forces the linings
against the rotor, creating friction to stop the vehicle.

5C±66
POWER±ASSISTED BRAKE SYSTEM
Diagnosis
Road Testing The Brakes
Brake Test
Brakes should be tested on a dry, clean, reasonably
smooth and level roadway. A true test of brake
performance cannot be made if the roadway is wet,
greasy or covered with loose dirt where all tires do not grip
the road equally. Testing will also be adversely affected if
the roadway is crowned so as to throw the weight of the
vehicle toward wheels on one side or if the roadway is so
rough that wheels tend to bounce. Test the brakes at
different vehicle speeds with both light and heavy pedal
pressure; however, avoid locking the wheels and sliding
the tires. Braking without locking the tires will stop the
vehicle in less distance than braking to a skid (which has
no brake efficiency). More tire to road friction is present
while braking without locking the tires than braking to a
skid.
The standard brake system is designed and balanced to
avoid locking the wheels except at very high deceleration
levels.
It is designed this way because the shortest stopping
distance and best control is achieved without brake
lock±up.
Because of high deceleration capability, a firmer pedal
may be felt at higher deceleration levels.
External Conditions That Affect Brake Performance
1. Tires: Tires having unequal contact and grip on the
road will cause unequal braking. Tires must be
equally inflated, identical in size, and the thread
pattern of right and left tires must be approximately
equal.
2. Vehicle Loading: A heavily loaded vehicle requires
more braking effort.
3. Wheel Alignment: Misalignment of the wheels,
particularly in regard to excessive camber and caster,
will cause the brakes to pull to one side.
Brake Fluid Leaks
With engine running at idle and the transmission in
ªNeutralº, depress the brake pedal and hold a constant
foot pressure on the pedal. If pedal gradually falls away
with the constant pressure, the hydraulic system may be
leaking.
Check the master cylinder fluid level. While a slight drop in
the reservoir level will result from normal lining wear, an
abnormally low level in reservoir indicates a leak in the
system. The hydraulic system may be leaking internally
as well as externally. Refer to
Master Cylinder Inspection.
Also, the system may appear to pass this test but still
have slight leakage. If fluid level is normal, check the
vacuum booster push rod length. If an incorrect length
push rod is found, adjust or replace the push rod. Check
the brake pedal travel and the parking brake adjustment.
When checking the fluid level, the master cylinder fluid
level may be lower than the ªMAXº mark if the front and
rear linings are worn. This is normal.
Warning Light Operation
When the ignition switch is in the START position, the
ªBRAKEº warning light should turn on and go off when the
ignition switch returns to the ON position.
The following conditions will activate the ªBRAKEº light:
1. Parking brake applied. The light should be on
whenever the parking brake is applied and the ignition
switch is on.
2. Low fluid level. A low fluid level in the master cylinder
will turn the ªBRAKEº light on.
3. During engine cranking the ªBRAKEº light should
remain on. This notifies the driver that the warning
circuit is operating properly.

5C±67 POWER±ASSISTED BRAKE SYSTEM
General Diagnosis
ConditionPossible causeCorrection
Brake PullTire inflation pressure is unequal.Adjust
Front wheel alignment is incorrect.Adjust
Unmatched tires on same axle.Tires with approx. the same amount
of tread should be used on the same
axle.
Restricted brake pipes or hoses.Check for soft hoses and damaged
lines. Replace with new hoses and
new double walled steel brake
piping.
Water or oil on the brake pads.Clean or replace.
Brake pads hardened.Replace
Brake pads worn excessively.Replace
Brake rotor worn or scored.Grind or replace.
Disc brake caliper malfunctioning.Clean or replace.
Front hub bearing preload incorrect.Adjust or replace.
Loose suspension parts.Check all suspension mountings.
Loose calipers.Check and tighten the bolts to
specifications.
Brake Roughness or Chatter
(Pulsates)Excessive lateral runout.Check per instructions. If not within
specifications, replace or machine
the rotor.
Parallelism not within specifications.Check per instructions. If not within
specifications, replace or machine
the rotor.
Pad reversed (steel against iron).Replace the brake pad and machine
rotor to within specifications.
Excessive Pedal EffortMalfunctioning vacuum booster.Check the vacuum booster operation
and repair, if necessary.
Partial system failure.Check the front and rear brake
system for failure and repair. Also,
check the brake warning light. If a
failed system is found, the light
should indicate failure.
Excessively worn pad.Check and replace pads in sets.
Piston in caliper stuck or sluggish.Remove caliper and rebuild.
Fading brakes due to incorrect pad.Remove and replace with original
equipment pad or equivalent.
Vacuum leak to vacuum booster.Check for ruptured or loose hose.
Check the direction of check valve
within vacuum hose.Correct vacuum hose direction.
Grease on the brake pads.Replace or clean.
Excessive Brake Pedal TravelAir in hydraulic circuit.Bleed the hydraulic circuit.
Level of brake fluid in the reservoir
too low.Replenish brake fluid reservoir to
specified level and bleed hydraulic
circuit as necessary.
Master cylinder push rod clearance
excessive.Adjust
Leakage in hydraulic system.Correct or replace defective parts.

5C±69 POWER±ASSISTED BRAKE SYSTEM
Condition CorrectionPossible cause
Poor Brake ActionMaster cylinder faulty.Correct or replace.
Vacuum booster faulty.Correct or replace.
Level of brake fluid in reservoir too
low.Replenish and bleed.
Air in hydraulic circuit.Bleed
Disc brake caliper faulty.Clean or replace.
Water or oil on brake pads.Clean or replace.
Brake pads in poor contact with the
rotor.Correct
Brake pads worn.Replace
Brake disc rusted.Grind or replace.
Check valve in vacuum hose faulty.Correct or replace.