Chevrolet 1977 10 Series, Repair Manual, Page: 182 / 468

5-16 OVERHAUL MANUAL
POW ER PISTON
SN A P R IN G
Fig. 5-1 1C--R em oving P o w e r Piston S nap Ring
13. Remove floating control valve assembly from push
rod as it m ust be replaced by a new floating control valve
assembly at rebuild.
14. The m aster cylinder push rod can now be pushed
from center of reaction retainer. Remove "O" ring from
groove in m aster cylinder piston rod.
Cleaning of Parts
1. Use denatured alcohol to clean thoroughly all metal
brake parts. Im m erse in cleaning fluid and brush with hair
brush to remove foreign m atter. Blow out all passages,
orifices and valve holes. A ir dry and place cleaned parts on
clean paper or lint free clean cloth.
2. If slight rust is found inside either front or rear
housing assemblies, polish clean with crocus cloth or fine
emery paper, washing clean afterw ards with specified
cleaning fluid.
Fig. 5-1 2C~Removing A ir Valve Assem bly
CAUTION: I f there is any suspicion o f
contamination or any evidence o f corrosion ,
completely flush hydraulic brake system. Failure to
clean hydraulic brake system can result in early
repetition o f trouble. Use o f gasoline, kerosene,
anti-freeze alcohol or any other cleaner with even
a trace o f mineral oil will damage rubber parts.
D irt is the m ajor cause of trouble and wear in service.
Be sure to keep parts clean. Rewash at reassembly if there
is any occasion to doubt cleanliness-such as parts dropped
or left exposed for eight hours or longer.
Inspection and Replacement of Parts
1. Inspect all rubber parts. Wipe free of fluid and
carefully inspect each rubber part for cuts, nicks or other
damage. These parts are the key to control of fluid or air flow
and should account for the m ajority of troubles traceable to
leakage. Re-use rubber parts only if a fairly new unit is
disassembled for some particular trouble and only then if
there is no doubt that the parts are in equal-to-new condition.
Badly damaged items or those which would take extensive
work or time to repair should be replaced. In case of doubt,
install new parts for safety.
2. Inspect in accordance with Inspection Table: (The
table is organized by power brake unit groups.)
Assembly
Be certain that all rubber parts are clean at reassembly.
Rewash in specified cleaning fluid if there is any doubt of
cleanliness. Be careful during rebuild process that no grease
or mineral oil comes in contact with rubber parts of power
brake unit. Lubricate rubber parts with Delco approved
lubricant or equivalent.
Front Housing Group
1. Install a new vacuum check valve using a new
grommet.
2. Place new front housing seal in housing so flat surface
of cup lies against bottom of depression in housing.
Power Piston Group
1. Place new "O" ring in groove on the m aster cylinder
piston rod. W ipe a thin film of Power Brake Lube or
equivalent on "O" ring.
2. M aster cylinder piston rod is now inserted through
the reaction retainer so round end of piston rod protrudes
from end of the tube on reaction retainer.
3. Place J-2 1524 power piston wrench in a vise. Position
power piston on wrench with three lugs fitting into notches
in power piston.
4. Poistion new "O" ring on air valve in second groove
from push rod end.
5. On reassembly of power piston, floating control valve
assembly m ust be replaced with a new one since the force
required to remove it distorts com ponent parts.
6. Place floating control valve on push rod-air valve
assembly so flat face of valve will seat against valve seat on
air valve.
7. Wipe a thin film of Power Brake Lube (or equivalent)
on large O.D. of floating control valve and on "O" ring on
air valve.
8. Press air valve-push rod assembly, air valve first, onto
its seat in tube of power piston.
9. Place floating control valve retainer over push rod so
flat side seats on floating control valve.
10. Start floating control valve and its retainer into
power piston tube. Press the floating control valve to seat in
3/8"
E X T E N S I O N
J-9746