Pontiac tempest 1968 Service Manual page 210

H E A V Y D U T Y POWER BRAKES
5C-7
ASSEMBLY OF VACUUM CHECK VALVE, REACTION
DISC AND PUSH ROD (Fig. 5C~1)
Apply power brake lubricant liberally to entire
surface of rubber reaction disc and to piston end of
hydraulic push rod. Place reaction disc on piston
end of push rod,
CAUTION; Under NO condition should lubricant
be allowed to get on adjustment screw or threads.
Insert push rod with reaction disc on piston end
into cavity in front plate hub. Twist push rod to make
certain reaction disc is seated in front plate hub and
to eliminate a i r bubbles between hub, disc and push
rod piston. Assemble seal, support plate side first,
over adjustment screw end of push rod. Press seal
Into recess In front shell until seal bottoms against
shell.
If vacuum check valve was removed, wet new
grommet in alcohol and press grommet into front
shell, beveled side first. Make certain grommet is
seated in shell. Wet shoulder of check valve and i n ­
side diameter of grommet with alcohol and assemble
check valve In grommet. Press check valve Into
grommet until entire circumference of check valve
flange bears against grommet.
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n
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Fig. 5C-6 Gaging Push Rod Length
distance A (Fig. 5C-6) from end of hydraulic push
rod to master cylinder mounting face on front
shell. This dimension A, as shown in Figure 5C-
6, should be 1.200". If push rod length is not
correct, follow adjustment procedure below. When
push rod length is correct, attach master cylinder
to power section with lockwashers and nuts.
Tighten nuts securely. Install clevis on threaded
end of valve rod.
ASSEMBLY OF VALVE ROD, FILTERS, RETAINER AND
POPPET PARTS (Fig.5C-2)
Wet poppet valve in alcohol and assemble poppet
in valve housing, small diameter end of poppet f i r s t ;
wet poppet retainer i n alcohol and assemble i n
housing with flange out. Press in against retainer to
make certain shoulder on retainer is positioned i n ­
side poppet. Assemble retainer, valve silencers and
filters and valve return spring over ball end of valve
rod, as shown. Wet rubber grommet in valve plunger
inside valve hub and ball end of valve rod with
alcohol. Guide spring, filters and silencers into
valve housing and assemble ball end of valve rod in
valve plunger. Tap end of valve rod with soft ham­
mer to lock ball end of rod in valve plunger
grommet. Press filters into position in housing and
assemble retainer on end of valve housing, being
careful not to chip plastic.
ASSEMBLY OF DUST GUARD AND MASTER CYLINDER
TO POWER UNIT (Fig. 5C-1)
Assemble silencer in dust guard. Dip small diam­
eter of dust guard in alcohol and assemble dust guard
over end of valve rod, using care to avoid tearing
guard. Press guard against valve housing and seat
large end of guard over scalloped flange of rear
shell.
PUSH ROD ADJUSTMENT
The self-locking adjustment screw is set to cor­
rect dimension at time of original assembly of power
unit. Under normal service, no further adjustment
should be needed provided push rod assembly re­
mains i n original unit. If, however, push rod is
transferred to another unit or new push rod is used,
adjustment w i l l be necessary. To adjust push rod,
hold serrated end of push rod with pliers and turn
adjusting screw IN to shorten or OUT to lengthen
push rod. Measure push rod height with push rod i n ­
stalled i n unit, using either a height gauge or tool
J 7723-01. See Figure 5C-7 for details for making
height gauge.
« I 5
c
( 6
' 3 2
# 1 5 O R # 1 6
U . S . S . G A U G E
S H E E T S T E E L
NOTE: Before mounting master cylinder, check
Fig. 5 C - 7 Push Rod Gauge