Page 737 of 2100

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.
Page 738 of 2100
5C±58
POWER±ASSISTED BRAKE SYSTEM
Disassembled View
305RS006
Legend
(1) Boot
(2) Piston Assembly
(3) Piston Cup
(4) Return Spring
(5) Bleeder
(6) Wheel Cylinder
Disassembly
1. Remove boot (1) and piston assembly (2).
2. Remove piston cup (3) from piston assembly (2).
3. Remove return spring (4) and bleeder (5) from wheel
cylinder (6).
Inspection and Repair
1. Make necessary parts replacement if wear, damage,
corrosion or any other abnormal condition are found
through inspection.
Check the following parts;
Wheel cylinder body
Cylinder bore
Piston
Return spring
BleederNOTE: Replace the piston cups and boots each time the
wheel cylinder is overhauled. Discard these used rubber
parts and replace with new ones.
Reassembly
1. Lubricate the cylinder bore with clean rubber grease.
305RS007
2. Install bleeder (5) to wheel cylinder (6).
Torque: 10 N´m (8 lb ft)
305RS008
Page 739 of 2100
5C±59 POWER±ASSISTED BRAKE SYSTEM
3. Install new piston cups (3) on each piston so that the
flared end of the cups are turned to the inboard side of
the pistons.
Attach the return spring (4) and the boot (1) to the
piston.
305RS009
4. Apply DELCO silicone lube No. 5459912 (or
equivalent) to the piston and the inner face of the
boots.
5. Install piston assembly (2) to wheel cylinder (6).
Page 740 of 2100
5C±60
POWER±ASSISTED BRAKE SYSTEM
Main Data and Specifications
General Specifications
Rear drum brake
TypeLeading-trailing, non-servo
Drum inside diameter295 mm (11.6 in)
Wheel cylinder diameter22.22 mm (7/8 in)
Torque Specifications
E05RW010
Page 741 of 2100

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. . . . . . . .
Page 742 of 2100

5C±62
POWER±ASSISTED BRAKE SYSTEM
Brake Pads Inspection 5C±101. . . . . . . . . . . . . . . . .
Brake Pads and Associated Parts 5C±101. . . . . . .
Removal 5C±102. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±102. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Disc Brake Rotor (4y4 Model) 5C±104. . . . . . . .
Inspection 5C±104. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Brake Rotors 5C±104. . . . . . . . . . . . . . . .
Refinishing Brake Rotors 5C±104. . . . . . . . . . . . . . .
Rear Drum (In Disc) Inside Diameter
Check 5C±105. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Disc Brake Caliper Assembly
(4y4 Model) 5C±106. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Disc Brake Caliper Assembly and
Associated Parts 5C±106. . . . . . . . . . . . . . . . . . . . . .
Removal 5C±106. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±107. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Disc Brake Caliper (4y4 Model) 5C±108. . . . . .
Rear Disc Brake Caliper Disassembled
View 5C±108. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 5C±109. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±109. . . . . . . . . . . . . . . . . . Reassembly 5C±109. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications
(4y4 Model) 5C±111. . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Lining 5C±112. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Lining and Associated Parts 5C±112. . . . . . .
Removal 5C±112. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Lining Inspection 5C±113. . . . . . . . . . . . . . . .
Installation 5C±113. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drum Brake Adjustment (4y2 Model) 5C±114. . . . .
Servicing The Brake Drum 5C±114. . . . . . . . . . . . . .
Wheel Cylinder Assembly (4y2 Model) 5C±115. . . . .
Wheel Cylinder Assembly and Associated
Parts 5C±115. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±115. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±115. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembled View 5C±116. . . . . . . . . . . . . . . . . . . .
Disassembly 5C±116. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±116. . . . . . . . . . . . . . . . . .
Reassembly 5C±116. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±118. . . . . . . . . . . . .
Service Precaution
WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE
SRS
COMPONENT AND WIRING LOCATION VIEW
IN
ORDER TO DETERMINE WHETHER YOU ARE
PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING. WHEN YOU
ARE PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING, REFER TO
THE
SRS SERVICE INFORMATION. FAILURE TO
FOLLOW WARNINGS COULD RESULT IN POSSIBLE
AIR BAG DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.
General Description
Master Cylinder Assembly
330R200002
Page 743 of 2100

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.
Page 744 of 2100

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.