Pontiac FIREBIRD 1972 Service Manual page 489

5D-12 1972 PONTIAC SERVICE MANUAL
valve-pushrod assembly is serviced as a com-
plete assembly.
MASTER CYLINDER
INSPECT
Replace air filter element if dirty. Do not clean.
DISASSEMBLE (Fig. 50-14)
MASTER CYLINDER
Refer to Section 5
-
BRAKES-GENERAL for disassem-
bly procedure.
NOTE: Do not remove front outlet tube seat
unless tube seat is damaged and requires re-
placement.
CAUTION: It is important that all parts be
placed on a clean paper after being cleaned to
prevent the possibility of dirt being assembled
into unit or grease contacting any rubber parts.
Thoroughly wash all parts in alcohol and air dry. Blow
dust and cleaning fluid out of all internal passages.
POWER BRAKE
INSPECT
Inspect all parts for scoring, pitting, dents or nicks. Small
impe~fections can be smoothed out with fine emery cloth.
Replace if badly nicked, scored or otherwise damaged.
MASTER CYLINDER
INSPECT
Inspect bore from the open end. The bore should be free
from scores, deep scratches and corrosion. If it appears
that corrosive brake fluid has damaged the bore, replace
damaged partsand flush out entire brake system including
wheel cylinders.
The sealing surfaces should be clean and smooth. Check
for cracks and damaged threads. Be sure that the by-pass
and compensating ports to the master cylinder are not
restricted.
Check for distortion of all springs and deterioration of all
rubber parts. Any evidence of soft or swollen rubber parts
indicates contaminated brake fluid requiring flushing of
the entire brake system and replacement of wheel cylinder
cups, as well as all rubber parts in master cylinder.
ASSEMBLE
Refer to Section 5
-
BRAKES-GENERAL for assembly
procedures.
POWER PISTON
ASSEMBLY (Fig. 5D-9)
Lubricate the "0" ring seal with silicone lubricant
and place in groove on air valve.
Wipe a thin film of silicone lubricant on large and
small O.D. of floating control valve.
NOTE: If floating control valve requires re-
placement, it will be necessary to replace the
complete air valve-pushrod
assembl'
since the
floating control valve is a component part of
this assembly and cannot be removed.
Place the air valve end of the air valve-pushrod as-
sembly into the tube of the primary piston. Manually
push the air valve-pushrod assembly until the air
valve starts into its bore. Push the control valve as-
sembly into the tube so that the complete control
valve is just inside the tube.
Insert control valve retainer over end of control valve
so that closed side of retainer rests against control
valve.
Installer tool J 23175 fits the I.D. of the floating
control valve retainer. Push floating control valve
assemlby to its seat in tube of power piston (Fig.
5 0 - 15).
Place pushrod limiter washer over pushrod and posi-
tion against floating control valve retainer.
Stretch the foam filter element over pushrod eye and
press into primary power piston tube.
Using snap ring pliers, place the retaining ring into
groove on air valve (Fig. 5D- 16).
Position the rubber reaction bumper on end of air
valve.
NOTE: Tolerances of the component parts af-