Opel Frontera UBS. Manual - part 219

 

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Opel Frontera UBS. Manual - part 219

 

 

POWER ASSISTED BRAKE SYSTEM  5C – 21

SPECIAL TOOLS

ILLUSTRATION

PART NO.

PARTNAME

Primary piston holder

5-8840-2306-0

(including master cylinder attach-

(J-39242)

ment and master cylinder plug)

5-8840-0277-0

Radiator cap tester

(J-24460-01)

5-8840-2300-0

Push rod gauge

(J-39216)

5-8840-0279-0

Vacuum pump

(J-23738-A)

5-8840-2305-0

Push rod support

(J-39241)

5C – 22 POWER ASSISTED BRAKE SYSTEM

GENERAL DESCRIPTION

MASTER CYLINDER

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) The master cylinder is not repairable. If found

defective, it must be replaced as complete
assembly.

2) If any hydraulic component is removed or

disconneted, it may be necessary to bleed all or
part of the brake system.

3) The torque values specified are for dry,

unlubricated fasteners.

4) Perform service operations on a clean bench free

from all mineral oil materials.

330RW013

POWER ASSISTED BRAKE SYSTEM  5C – 23

VACUUM BOOSTER

This booster is a tandem vacuum unit with a diaphragm effective diameter 205 mm + 230 mm (gasoline
engine model) / 180 mm + 205 mm (diesel engine model).  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 one side of each
diaphragm to provide the power assist.  When the service brake is released, the atmospheric air is shut
off from the one side of each diaphragm.  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 – 24 POWER ASSISTED BRAKE SYSTEM

DISC BRAKES

The disc brake assembly consists of a caliper, piston, rotor, pad assembly and support bracket.  The
caliper assembly has a single bore and is mounted to the support bracket with 2 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 service operation 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 acts equally against the piston and the bottom of the caliper bore to move the piston outward
and to move (slide) the caliper inward resulting in a clamping action on the rotor.  This clamping action
forces the linings against the rotor, creating friction to stop the vehicle.

Front disc brakes

Rear disc brakes

 

 

 

 

 

 

 

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