Inspect Hydraulic Master Cylinder Assembly; Inspect Air Filters; Power Unit And Master Cylinder; Master Cylinder-Exploded View - Pontiac Grand Prix Service Manual

5B-4
1969 PONTIAC SERVICE MANUAL
Fig. 58-5 Master Cylinder-Exploded View
1. Snap Ring
2. Splash Shield
Retuiner
3. Splash Seal
4. Secondary Seal
5. Rear Piston and
Spring Assembly
6. Primary Cup
7. Secondary Seals
8. Front (Floating)
Piston
9. Protector
10. Primary Cup
11. Retuiner
12. Front Piston Return
Spring
13. Piston Stop Screw
and Seal
14. Tube Seats
15. Check Valves
16. Springs
17. Master Cylinder
Casting
18. Hermetic
Diaphragm
19. Reservoir Cover
20. Bale-Type
Retuiner
inside of front housing is slightly scored or scratched,
clean with crocus cloth or fine emery cloth. If scratches
cannot be removed, replace housing.
All rubber parts should be replaced, regardless of
condition, and those parts which come in contact with
brake fluid should be rewashed in clean alcohol before
reassembly.
CAUTION: It is important that all parts be placed on a
clean paper or cloth afier being cleaned to prevent the
possibility of dirt being assembled into unit or grease
contacting any rubber parts.
INSPECT POWER BRAKE ASSEMBLY
Inspect all parts for scoring, pitting, dents or nicks.
Small imperfections can be smoothed out with fine
emery cloth or parts replaced if badly nicked, scored,
or otherwise damaged.
INSPECT HYDRAULIC MASTER CYLINDER
ASSEMBLY
Inspect bore from the open end. The bore should be
free of scoring, rust pitting or etching. If any of these
are apparent, master cylinder must be replaced. If it
appears that contaminants have 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 reservoirs 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.
INSPECT AIR FILTERS
Replace air filters if dirty. Do not clem.
POWER UNIT AND MASTER CYLINDER
-
ASSEMBLE
MASTER CY LlNDER ASSEMBLE (Fig. 56-5)
1. Clamp master cylinder in vise with open end slightly
above horizontal.
2. Install new secondary seals, back to back, in grooves
on rear end of front piston. Dip seals in brake fluid
and lift them'carefully into grooves with dull scribe.
@
Slide protector and primary cup onto nose of front
piston.
3. Stack front piston return spring and retainer on nose
of front piston and dip assembly in brake fluid. Press
and twist piston to ease cups past snap ring groove into
bore. Slide assembly to bottom of bore.
4. Dip new rear piston and spring assembly in brake
fluid and slide assembly into bore. Use scribe and
presspiston to ease cups into bore.
5. Press in against rear piston with round-end rod to
compress .return springs. Do NOT use screwdriver or
other sharp-edged tool since this will damage the push
rod seat inside the piston. Maintain pressure on piston
and use Tru-Arc pliers to install snap ring in groove
inside bore. Make certain that snap Ping is securely
seated in groove.
6. Maintain pressure on rear piston while installing
piston stop screw and new O-ring seal in port