HEAVY
DUTY
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 air 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 in-
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.
$—.
1
n
$—.
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
first;
wet
poppet retainer in alcohol and
assemble
in
housing
with
flange out.
Press
in against retainer to
make certain shoulder on retainer is positioned in-
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 in
original
unit. If, however, push rod is
transferred to another unit or new push rod is
used,
adjustment
will
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 in-
stalled in unit, using either a height
gauge
or
tool
J 7723-01. See Figure 5C-7 for details for making
height
gauge.
«I5
c
(6
'32
#15
OR #16
U.S.S.
GAUGE
SHEET
STEEL
NOTE:
Before
mounting master cylinder, check
Fig.
5C-7
Push
Rod
Gauge
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