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5-2
1
1977 PONTIAC SERVICE MANUAL
5. In order to insure correct assembly of the primary
assembly, a complete primary piston assembly is included in
the repair kits.
6. Coat bore of master cylinder with clean brake fluid.
Coat primary and secondary seals on secondary piston with
clean brake fluid. Insert the secondary piston spring retainer
into secondary piston spring. Place retainer and spring over
end of secondary piston, so that retainer locates inside lip of
primary cup.
7. Hold master cylinder with open end of bore down,
push secondary piston into bore, so that spring will seat
against closed end of bore.
8. Place master cylinder in a vise with open end of bore
up. Coat primary and secondary seal on primary piston with
clean brake fluid. Push primary piston assembly, spring end
first, into bore of master cylinder. Hold the piston down and
snap lock ring into position in groove in inside diameter of
bore.
9. Continue to hold primary piston down and install stop
screw. (If so equipped)
10. Install a new reservoir diaphragm in reservoir cover
where needed, and install cover on master cylinder. Beaded
side faces master cylinder casting to insure positive sealing.
The bail wire is not pushed into position to hold reservoir
cover.
11. (Manual brake only.) Assemble push rod through
push rod retainer, if it has been disassembled. Push retainer
over end of master cylinder. Assemble new boot over push
rod and press it down over the push rod retainer. Thread jam
nut down to shoulder on push rod. Thread clevis down to jam
nut. Torque nut against clevis to 14 lb. ft.
Installation of Brake Master Cylinder
1. (Manual Brake only) Connect push rod to brake pedal
pin and install retainer while holding master cylinder in place.
See Fig. 5-35.
2. Install master cylinder on dash or power cylinder.
Torque nuts to 25 lb. ft.
C A UTI 0 N: This brake master cylinder to cowl
fastener is an important attaching part in that it
could affect the performance of vital components
and systems, and/or could result in major repair
expense. It must be replaced with one of the same
part number, or with an equivalent part, i f
replacement becomes necessary. Do not use a
replacement part o f lesser quality or substitute
design. Torque values must be used as specified
dunng reassembly to assure proper retention of
this part.
3. Connect brake pipes to master cylinder.
4. Bleed hydraulic system.
5. Road test car for proper brake performance.
DISC BRAKES
MAINTENANCE AND ADJUSTMENTS
Lining Inspection
Inspect the brake linings every 6,000 miles and any time
that the wheels are removed (tire rotation, etc.). Check both
ends of the outboard shoe by looking in at each end of the
caliper. See Fig. 5-37. These are the points at which the
highest rate of wear normally occurs. However, at the same
time, check the lining thickness on the inboard shoe to make
sure that is has not worn prematurely. Look down through
the inspection hole in the top of the caliper to view the
inboard shoe. Whenever the thickness of any lining is worn
to within .020 on X, A, B, or .030 on H of rivet at either end
of the shoe, all disc brake shoe and lining assemblies should
be replaced at the same time. See Fig. 5-38.
CALIPER REMOVAL AND
INSTALLATION
EXCEPT H SERIES
Caliper Removal
See Warning Page 5-1
1. Remove two thirds of the total fluid capacity from the
front master cylinder reservoir. Removal of the fluid is
necessary to prevent reservoir overflow when the caliper
piston is pushed back in its bore to remove the caliper. This
may be done by breaking the front line connection at the
master cylinder and bleeding down the fluid level. Do not
remove the brake line or completely empty the reservoir or
it will be necessary to bleed the hydraulic system. Discard
--
do not attempt to reuse
--
the brake fluid removed.
2. Raise the car and remove the wheel covers and wheel
assemblies. Position a 7 inch "C" clamp on the caliper so that
the solid side of the clamp rests against the inside of the
caliper and the screw end rests against the metal part of the
outboard shoe. See Fig. 5-39. Tighten the "C" clamp until
the caliper moves away from the car far enough to push the
piston to the bottom of the piston bore. This will allow the
shoes to back off from the rotor surfaces. Remove the "C"
clamp.
3. It is not necessary to disconnect the brake hose for
shoe and lining replacement. Remove the two mounting bolts
which attach the caliper to the support bracket. See Figure
5-40. Lift the caliper off the rotor and remove the inboard
shoe. Dislodge the outboard shoe and position the caliper on
the front suspension arm so that the brake hose will not
support the weight of the caliper. Remove the shoe support
spnng from the cavity in the piston.
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