Opel 1900 1973, Service Manual

Page: 261 / 625

CONTENTS
Subject Page No.
DESCRIPTION AND OPERATION:
Power Brake Booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Master Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIAGNOSIS:
Power Brake
Trouble Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND ADJUSTMENTS:
Checking Brake Booster Operation
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Booster Filter Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Valve Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAJOR REPAIR:
Brake Booster Removal and Installation
. . . . . . . . . . . . . . . . . .
Master Cylinder Overhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS:
General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 1973 OPEL SERVICE MANUAL
POWER BRAKE BOOSTER AND MASTER CYLINDER
DESCRIPTION AND OPERATION
POWER BRAKE BOOSTER
The vacuum power cylinder contains the power pis-
ton assembly which houses the control valve and
reaction mechanism and the power piston return
spring. The control valve is composed of the air valve
and the floating control valve assembly. The reaction
mechanism consists of a hydraulic piston, reaction
plate, and a series of springs. An air filter element is
assembled around the push rod and fills the cavity
inside the of the power piston. This keeps dirt
and dust from entering the vacuum booster. The
push rod, which operates the air valve, projects out
of the end of the power cylinder ‘housing through a
boot.
MASTER CYLINDER
The master cylinder is composed a primary piston
and secondary piston; it is supplied with fluid from
two separate reservoirs. A check valve is mounted on
the primary circuit which supplies fluid to the rear
brakes. This keeps a slight static pressure in the rear
brake system. When the pedal is depressed, the push
rod moves the two pistons forward simultaneously
until the seals of the two pistons cover the compen-
sating ports in the cylinder. The pressure is increased
in the two chambers simultaneously, thus supplying
fluid to both front and rear brake systems.
Figure Brake Booster Attachment (Opel 1900
and Manta)
In the GT, the brake fluid container is arranged at
right angles to the tandem brake master cylinder. See
Figure It is pushed over the feed port of the
rear brake circuit onto the brake master cylinder and