5-14
1968
PONTIAC
SERVICE
MANUAL
sembly, spring end
first,
into
bore of master
cyl-
inder.
Hold
piston down and
snap
lock
ring
into
position
in small groove in
I.D.
of bore.
9. Continue to
hold
rear piston down,
which
will
move
front
piston
forward
far enough to clear stop
screw hole located in bottom of
front
fluid
reservoir.
Position
stop screw in Its hole and tighten to a
torque of 33 pound inches,
10.
Install
a new reservoir diaphragm in reservoir
cover, if needed.
Install
cover on master cylinder.
Beaded side
faces
casting to insure positive sealing.
Push
bail
wires
Into
position to
hold
reservoir cover.
11. Assemble push rod through push rod retainer,
if
disassembled.
12.
Push retainer over end of master cylinder.
Assemble new boot over push rod and
press
It down
over push rod retainer.
REPLACE
1.
Mount
and
secure
master cylinder to dash,
tighten
bolt
to 25 ft.lb. torque. The flange on the
push rod retainer and flange on boot
will
be held
between the dash and master cylinder.
2.
Connect push rod to brake pedal and attach
brake lines to appropriate
boss
on master cylinder.
Outlet
boss
thread
sizes
and brake
line
fittings
for
front
and rear are different, to
assure
that correct
connections are made,
providing
original
brake lines
have not been changed.
3. Bleed master cylinder as though it were two
separate
units. See section on bleeding brakes.
After
bleeding,
fill
reservoirs
with
brake
fluid
to
within
1/2" of top of reservoir.
WHEEL
CYLINDER
REMOVE
1. Raise wheels of vehicle and remove wheel and
drum
assembly.
2.
On Tempests, remove brake pipe.
3. Disconnect
hose
from
wheel cylinder on Fire-
bird
and Pontiac.
4. Remove brake
shoes
to protect them
from
drip-
ping
fluid.
5. Remove wheel cylinder.
The internal wheel cylinder boots should be re-
moved
from
cylinder body
only
when they are
visibly
damaged or leaking
fluid.
Wheel
cylinders having
torn,
cut or heat-cracked
boots should be completely overhauled.
Inspection
for leakage may be accomplished at the
boot
center hole after removal of the
link
pin.
Fluid
coatings on the piston
within
the cylinder and on the
end of the
link
pin removed
from
the boot are nor-
mal,
as the cylinder contains a porous piston
which
is
Impregnated
with
a corrosion-inhibiting
fluid.
Fluid
spilling
from
the boot center hole, after the
link
pin is removed, indicates cup leakage and the
necessity for completely overhauling the cylinder.
DISASSEMBLE
(Fig. 5-12)
1.
Pull
boots
from
cylinder
ends
with
pliers and
discard
boots,
2.
Extract and discard pistons and cups.
3. Inspect cylinder bore. Check for staining or
corrosion.
It is
best
to discard a corroded cylinder.
NOTE;
Staining is not to be confused with
corro-
sion.
Corrosion
can be identified as pits or ex-
cessive
bore roughness.
4.
Polish any discolored or stained
area
with
crocus
cloth
by
revolving
the cylinder on the
cloth
supported by a finger. Do not slide the
cloth
In a
lengthwise
manner under pressure. Do not use any
other
form
of abrasive or abrasive
cloth,
5. Rinse the. cylinder in brake
fluid.
6.
Shake
excess
rinsing
fluid
from
the cylinder.
Do
not use a rag to dry the cylinder, as
lint
from
the
rag cannot be kept
from
the cylinder bore surfaces.
7. Lubricate the cylinder bore and counterbore
with
brake
fluid
and Insert spring-expander
assem-
bly.
8.
Install
new cups making
sure
cups are
lint
and
dirt
free. Do not lubricate cups
prior
to assembly.
9.
Install
new pistons in the as received condition
to
Insure proper corrosion
Inhibiting
properties.
Do
not lubricate pistons
with
brake
fluid.
10.
Press
new boots
Into
cylinder counterbores by
hand. Do not lubricate boots
prior
to assembly.
REPLACE
1.
Install
wheel cylinder on backing plate
with
screws and
lock
washers. Tighten screws to 14 1/2
lb.
ft. torque (Pontiac) 8 lb. ft. torque (Tempest
and
Firebird).
2.
Replace wheel cylinder connecting
links.
3.
Install
brake
shoes
and springs.
4.
Connect
hose
or pipe to wheel cylinder. (Use
new gasket
with
hose.)
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