Pontiac FIREBIRD 1972 Service Manual page 427

5-24 1972 PONTIAC SERVICE MANUAL
the portion of front piston which contains small com-'
pensating holes.
Assemble a new primary seal and protector over end
of front piston with flat side of seal seating against
seal protector and protector against flange of piston
which contains the small compensating holes.
All master cylinder overhaul kits contain assembled
primary piston, making it unnecessary to assemble
any primary piston component parts.
Coat bore of master cylinder, primary and secondary
seals on front piston with clean brake fluid. Insert
secondary piston spring retainer into secondary pis-
ton spring. Place retainer and spring down over end
of front piston locating retainer inside lips of primary
cup.
Holding master cylinder wi'th open end of bore down,
push front piston into bore, seating spring against
closed end of bore.
Place master cylinder in vise with open end of bore
up. Coat primary and secondary seal on rear piston
with clean brake fluid. Push rear piston assembly,
spring end first, into bore of master cylinder. Hold
piston down and snap lock ring into position in small
groove in I.D. of bore.
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. Posi-
tion stop screw in its hole and tighten to a torque of
33 lb. in.
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.
Assemble push rod through push rod retainer, if
disassembled.
Push retainer over end of master cylinder. Assemble
new boot over push rod and press it down over push
rod retainer.
REPLACE
CAUTION: See Caution on page I of this Sec-
tion regarding the fasteners referred to in step
I below.
1. Mount and secure master cylinder to dash, tighten
fasteners to 25 lb. ft. torque. The flange on the push
rod retainer and flange on boot will be held between
the dash and master cylinder.
2. Connect ush rod to brake pedal and attach brake
I:
lines to appropriate bosses on master cylinder. Outlet
boss thread sizes and brake line fittings for front and
rear are different sizes to assure that correct connec-
tions are made, providing original brake lines have
not been changed.
3. Fill and bleed master cylinder as though it were two
separate units. See section on bleeding brakes. After
bleeding, fill reservoirs with brake fluid to within
1/4" of top of reservoir (Fig. 5-1 1).
WHEEL CYLINDER
REMOVE
1. Raise wheels of vehicle and remove wheel and drum
assembly.
2. Remove brake shoes to protect them from dropping
fluid.
3. Disconnect hose (front wheels) or pipe (rear wheels),
from wheel cylinder.
4. Remove wheel cylinder.
The internal wheel cylinder boots should be removed from
cylinder body only when they are visibly damaged or leak-
ing 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 normal, 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.
BOOT
L
PISTON CUP
Fig. 5-2 1 Wheel Cylinder
-
Exploded View