Opel Frontera UBS. Manual - part 214

POWER ASSISTED BRAKE SYSTEM  5C – 1

SECTION 5C

POWER ASSISTED BRAKE SYSTEM

CONTENTS

PAGE

Service Precaution ............................................................................................................. 5C- 2

Brake System Diagnosis .................................................................................................... 5C- 3

Troubleshooting ................................................................................................................. 5C- 5

Main Data and Specifications ........................................................................................... 5C- 7

Service Standard ................................................................................................................ 5C-  8

Servicing ............................................................................................................................. 5C-  9

Fixing Torque ...................................................................................................................... 5C-18

Special Tools....................................................................................................................... 5C-21

General Description ........................................................................................................... 5C-22

Master Cylinder.............................................................................................................. 5C-22

Vacuum Booster..............................................................................................................5C-23

Disc Brakes ..................................................................................................................... 5C-24

On-Vehicle Service ............................................................................................................. 5C-25

Brake Hose Replacement .............................................................................................. 5C-25

Brake Pipe Replacement ............................................................................................... 5C-27

P & B Valve ..................................................................................................................... 5C-28

P & B Valve Replacement .............................................................................................. 5C-29

Load Sensing Proportioning Valve (LSPV) .................................................................. 5C-30

Brake Pedal Replacement ............................................................................................. 5C-34

Stoplight Switch Replacement..................................................................................... 5C-36

Fluid Reservoir Tank ...................................................................................................... 5C-38

Master Cylinder Assembly ............................................................................................ 5C-39

Vacuum Booster Assembly ........................................................................................... 5C-41

Exterior Components .................................................................................................... 5C-44

SECTION

5C – 2 POWER ASSISTED BRAKE SYSTEM

Front Disc Brakes ........................................................................................................... 5C-47

Brake Pads Replacement .......................................................................................... 5C-47

Caliper Replacement ................................................................................................. 5C-50

Rebuilding the Caliper............................................................................................... 5C-53

Rear Disc Brakes ............................................................................................................ 5C-56

Brake Pads Replacement .......................................................................................... 5C-56

Caliper Replacement ................................................................................................. 5C-59

Rebuilding the Caliper............................................................................................... 5C-62

Unit Repair .......................................................................................................................... 5C-65

Master Cylinder.............................................................................................................. 5C-65

Vacuum Booster............................................................................................................. 5C-67

SERVICE PRECAUTION

WARNING: 
IF SO EQUIPPED WITH 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 specification. Following these instructions can help you avoid damage to
parts and systems.

POWER ASSISTED BRAKE SYSTEM  5C – 3

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 so that 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. Locked
wheels and sliding tires do not indicate brake
efficiency, since heavily braked but turning wheels
will stop the vehicle in less distance than locked
wheels. More tire-to-road friction is present with a
heavily braked turning tire then with a sliding tire.
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 tread
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
“Neutral”, 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 reservoir level will result from normal lining
wear, an abnormally low level in resevoir 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

5C – 4 POWER ASSISTED BRAKE SYSTEM

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 low from the “MAX” mark if the
front and rear linings are worn. This is not abnormal.

WARNING LIGHT OPERATION

When the ignition switch is in the START position, the
“BRAKE” warning light should glow and go OFF when
the ignition switch returns to the ON position.
The following conditions will activate the “BRAKE”
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 “BRAKE” light ON.

3. During engine cranking the “BRAKE” light should

remain ON. This notifies the driver that the
warning circuit is operating properly.

4. Low vacuum warning light. The vacuum warning

device is equipped on the diesel engine equipped
vehicles. The “BRAKE” light comes on when the
reserved vacuum is lowered to a critical level or
power brake line is damaged.

NOTE:

Depressing the brake pedal repeatedly may cause the
brake warning light to come ON when the engine is
running at idling speed or at low speed. This is
because the amount of vacuum is used more than
that supplied by the vacuum pump, however, no
problem will occur actually.

If the lamp is still lighting even after 2 or 3 seconds at
idling speed, the vacuum line may be defective.

ANTILOCK BRAKE SYSTEM (ABS)

Refer to Brake Control System for inspection and
diagnosis procedure of the hydraulic unit.