Pontiac tempest 1968 Service Manual page 179

5-14
1968 P O N T I A C SERVICE M A N U A L
sembly, spring end f i r s t , into bore of master c y l ­
inder. Hold piston down and snap lock ring into
position i n small groove i n I.D. of bore.
9. Continue to hold rear piston down, which w i l l
move front piston forward far enough to clear stop
screw hole located i n bottom of front fluid reservoir.
Position stop screw i n Its hole and tighten to a
torque of 33 pound inches,
10. Install a new reservoir diaphragm in reservoir
cover, i f 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 w i l l 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 i t were two
separate units. See section on bleeding brakes.
After bleeding, f i l l 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 F i r e ­
b i r d and Pontiac.
4. Remove brake shoes to protect them from d r i p ­
ping fluid.
5. Remove wheel cylinder.
The internal wheel cylinder boots should be r e ­
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 p i n 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 f o r m 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
d i r t free. Do not lubricate cups p r i o r to assembly.
9. Install new pistons i n 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 p r i o r 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 l b . 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.)