Pontiac tempest 1968 Service Manual page 197

5B-2
1968 P O N T I A C SERVICE MANUAL
SWITCH ADJUSTMENT
WITH PEDAL RELEASED, ADJUST SWITCH SO THAT
PLUNGER IS FULLY DEPRESSED AGAINST PEDAL
Fig. 5B-1 Power Brake System
4. Using tool J 9504, press down firmly and rotate
tool and housing clockwise so that cut- outs in rear
housing line up with indentation of front housing.
NOTE: Remove rear housing carefully as it is
spring-loaded and will tend to fly away from the
front housing.
5. Remove tool, housing, hydraulic push rod from
diaphragm plate (power piston) and return spring
from front housing.
6. If check valve needs replacing, push it and the
grommet out of the front of the housing.
7. Remove assembly from vise and remove master
cylinder assembly or Tool J-22805-01 from front
housing.
8. Remove front vacuum seal with a blunt tool.
2. Remove the two felt air silencers and the one
foam type filter. Be careful not to chip plastic
housing.
3. Remove diaphragm plate (power piston) from
rear housing.
4. Carefully remove rubber diaphragm from dia­
phragm plate.
5. Tilt diaphragm plate and depress valve operat­
ing rod slightly to remove valve assembly retainer
(valve plunger stop key). See Fig. 5B-3.
6. Pull control valve assembly straight out from
diaphragm plate and with a blunt tool, push reaction
disc out front of plate. Do not disassemble control
valve assembly.
7. Inspect rear vacuum seal. Remove only if nec­
essary to replace by driving out with a screwdriver
or punch.
POWER PISTON-DISASSEMBLE (Fig. 5B-4}
CAUTION: Exercise extreme care in handling
power piston, rubber surfaces and metal parts in
this assembly. They should be guarded against
grease, oil and foreign matter and must be pro­
tected from nicks or cuts that might be caused by
rough surfaces or damaged tools.
1. Remove boot and felt filter from power unit.
MASTER CYLINDER-DISASSEMBLE (Fig. 5B-5)
1. Pry splash seal and retainer out of shallow
cavity around master cylinder hub.
2. Press in against rear piston with round-end
rod to relieve spring load on piston stop screw under
master cylinder bore. Use 3/8" wrench to remove
stop screw and O- ring seal. Maintain pressure on