Master Cylinder Disassemble - Pontiac Grand Prix Service Manual

HEAVY DUTY POWER BRAKES 5D-5
-shanked screwdriver be inserted through the pushrod
eye, and using the screwdriver as a handle, pull the air
valve-pushrod assembly straight out (Fig. 5D-7).
NOTE: Removal of the air valve-pushrod assembly will
at50 release the control valve and retainer.
18. Remove
"0"
ring seal from air valve.
NOTE: k4e jloating control valve cannot be removed
j o m the pushrod
-
hence, the air valve-pushrod assembly
is serviced as a complete assembly.
MASTER CYLINDER
-
DISASSEMBLE (FIG.
'5D-8)
Refer to Section 5
-
STANDARD BRAKES for
disassembly procedures.
NOTE: On disc-brake equipped vehicles, only the rear
outlet contains a check valve. For this reason, do not
removejont outlet tube seat unless tube seat is hmaged
and requires replacement.
INSPECTION AND CLEANING
Thoroughly wash all parts in alcohol and air dry. Blow
dust and cleaning fluid out of all internal passages.
1
RESERVOIR COV
RESERVOIR COVER
RESERVOIR DIAPHRAGM
MASTER CYLINDER BODY
SECONDARY
PISTON ASSEMBLY
C4 UTION: It i s important that all parts be placed on a
Fig. 50-8 Master Cylinder
-
Exploded View
clean paper a f i r being cleaned to prevent the possibility
of dirt being assembled into unit or grease contacting
AIR FILTER
any rubber parts.
POWER BRAKE
Replace air filter element if dirty. Do not clean.
Inspect all parts for scoring, pitting, dents or nicks.
ASSEMBLE BRAKE UNIT
Small imperfections can be smoothed out with fine
emery cloth. Replace if badly nicked, scored or
MASTER CYLINDER
-
ASSEMBLE
otherwise damaged.
MASTER CYLINDER
Inspect bore from the open end. The bore should be
free from scores, deep scratches and corrosion. It it
appears that corrosive brake fluid has damaged the
bore, replace damaged parts and 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 requir-
ing flushing of the entire brake system and replace-
ment of wheel cylinder cups, as well as all rubber parts
in master cylinder.
Refer to Section 5
-
STANDARD BRAKES for
assembly procedures.
POWER PISTON
-
ASSEMBLE (Fig. 5D-3)
1. Lubricate the " 0 " ring seal with silicone lubricant
and place in groove on air valve.
2. Wipe a thin film of silicone lubricant on large and
small O.D. of floating control valve.
NOTE: If jloating controt valve requires replacement, it
will be necessary to replace the complete air valve
pushrod assembly, since the floating control valve is a
component part of this assembly and cannot be removed.
3. Place the air valve end of the air valve-pushrod
assembly into the tube of the primary piston. Manu-
ally push the air
valve-pushrod assembly until the air