Chevrolet 1977 Monte Carlo, Repair Manual

Page: 157 / 428

BRAKES 5-21
Front Housing Group
1. R em ove check valve from grom m et and then rem ove
grom m et from front housing; discard valve and grom m et.
2. R em ove front housing and holding fixture from vise;
then remove holding fixture from front housing.
Cleaning
U se clean brake fluid to thoroughly clean all reusable
brake parts. Im m erse in the cleaning fluid and brush m etal
parts w ith hair brush to rem ove foreign matter. B low out
all passages, orifices and valve holes. A ir dry and place
cleaned parts on clean paper or lint free clean cloth. If slight
rust is found inside either the front or rear h alf housing
assem blies, polish clean with crocus cloth or fine emery
paper, w ashing clean afterwards. D irt is the m ajor cause o f
trouble and wear in service. Be sure to keep parts clean until
re-assem bly . R e-wash at re-assem bly if there is any occasion
to doubt cleanliness--such as parts dropped or left exposed
for eight hours or longer.
NOTICE: If there is any suspicion of contami­
nation or any evidence of corrosion, completely
flush the vehicle hydraulic brake system. Failure
to clean the hydraulic brake system can result
in early repetition of trouble. Use of gasoline
kerosene, anti-freeze, alcohol or any other
cleaner, with, even a trace of mineral oil, will
damage rubber parts.
Inspecting Rubber Parts
W ipe fluid from the rubber parts and carefully inspect
each rubber part for cuts, nicks or other damage. These
parts are the key to the control o f fluid or air flow, if the
unit is in for overhaul, or if there is any question as to the
serviceability o f rubber parts, R E P L A C E them .
Inspecting Metal Parts
B A D L Y D A M A G E D IT EM S, O R T H O SE W H IC H
W O U L D T A K E E X T E N S IV E W O R K O R T IM E TO
R E P A IR , S H O U L D BE R E P L A C E D . In case o f doubt,
install new parts. D o not rely on the brake unit being
overhauled at an early or proper interval. N ew parts will
provide m ore satisfactory service, even if the brake unit is
allow ed to go beyond the desired overhaul period.
Assembly (Figs. 5-1D and 5-2D)
1. Be careful during the rebuild procedure that no
grease or mineral oil com es in contact w ith the rubber parts
o f the power brake unit.
2. Lubricate power head parts, as outlined below, with
silicone lubricant provided in the service repair kit.
Front Housing Group
1. Install new check valve grom m et in front housing
with beveled edge o f grom m et inside o f housing. D ip new
check valve in clean denatured alcohol and install in
g ro m m et-ch eck valve stem is to be outside o f housing.
2. Position and secure H old in g Fixture J-22805 to
m ounting studs, and place tool and front housing in a vise.
B e sure to align tool so that check valve is not damaged.
If either or both o f the housings are replaced, make sure
alignment marks are transferred to the new housing.
F ig . 5 - 4 D ~ l n s t a l l i n g R e a r H o u s in g S e a l
R ear Housing G roup
1. Place rear housing on a block o f w ood, stud side
down, and position housing seal in center hole. U se Tool
J-22677 (fig. 5 -4D ) to seat seal in recess o f rear housing.
T ool b ottom s against housing when seal is in place.
2. A ssem ble diaphragm plate assem bly (see fig. 5-2D).
a. A pply silicon e lubricant to outside diam eter o f
diaphragm plate and extension, to bearing surfaces o f air
valve and to outer edge o f valve poppet. Insert air valve and
push rod assembly in extension o f diaphragm plate. The air
valve, poppet valve and push rod are serviced as an assembly;
a com plete unit must be installed if there is damage to any
o f the com ponent parts.
b. D epress the push rod slightly and install the air valve
lock. M ake sure the lock indexes and retains the air valve.
c. Install the rolling diaphragm in the groove o f
diaphragm plate.
d. A pply silicone lubricant to surface o f reaction disc
and position disc in center bore o f diaphragm plate. U se
piston rod to seat disc in bore. M ake sure disc is fully seated
before removing piston rod. If reaction disc is not fully
seated, it will result in an erroneous push rod height
adjustment.
3. A pp ly silicone lubricant to I.D . o f rear housing seal
and diaphragm bead contact surface o f rear housing. Install
diaphragm plate assem bly in rear housing.
4. Place air filter elem ent over push rod and into
diaphragm plate extension. Install filter retainer.
O V E R H A U L M A N U A L