Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 177

5C–25

POWER–ASSISTED BRAKE SYSTEM

Vacuum Booster Assembly

Vacuum Booster Assembly and Associated Parts

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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.

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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.

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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 sure to apply NEGATIVE pressure after
installing a push rod gauge on the vacuum booster.

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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

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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.

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