Buick LeSabre 1965 Service Manual page 558

9 - 3 6 POWER BRAKES
BRAKES
6. Using pry bars as shown in
Figure 9-20, rotate housing into
the locked position.
CAUTION: Make certain nuts are
installed on studs so that threads
do not become damaged and be
extremely careful not to break
the studs loose in the rear hous-
ing. Also, do not put pressure on
the power piston tube when lock-
ing the housings7
7. Push the felt silencer over the
push rod to seat against the end of
the power piston tube. The snap
ring retainer is now placed on the
push rod so that it can hold the
silencer against the power piston
tube. The plastic boot is now
pushed to seat against the rear
housing. The raised tabs on the
side of the boot will locate in the
large holes in the center of the
brackets. The jam nut and clevis
can now be re-assembled to the
push rod.
e. Gauging Power
Brake Piston
The following gauging operation
is necessary only when a major
structural part such as the front
or rear housing, the power piston
assembly, the master cylinder
piston, or the master cylinder as-
sembly is replaced with a new
part. The gauge measures how
far the master cylinder push rod
projects from the front housing.
This dimension must be correct
to insure the proper clearance in
the master cylinder between the
primary cup and the compensating
port.
Make check as follows:
1. Place the power brake assem-
bly in a vise so that the master
cylinder is up. Remove the mas-
ter cylinder from the front
housing. The m a s t e r cylinder
push rod is now exposed.
2. Place Gauge J-7723-01 o v e r
the piston rod so that it fits be-
tween the two studs on the front
housing. It should be parallel to
the studs and resting on the sur-
face of the housing. The cutout
portion of the gauge should never
be lower than the end of the piston
rod, and the gap between the cut-
out in the gauge and the end of the
piston rod should never be more
than .010 inch. See Figure 9-33.
3. Any variation beyond these two
limits must be compensated for
by obtaining the service adjust-
able piston rod, Part #5464521,
and adjusting the screw in the end
to match the height of the gauge.
4. Replace the master cylinder on
the studs on the front housing. In-
stall nuts and lock washers on the
s t u d s and t o r q u e to 15-20
ft. lbs.
CAUTION: When replacing the
unit on the vehicle, start the en-
gine and allow vacuum to build
up before applying the brake.
9-20 INSTALLATION OF
POWER BRAKE UNIT
1. Place power brake unit in po-
sition on cowl and install four
nuts on studs. Torque nuts to
20-28 ft. lbs.
2. Using retainer and special
washer, connect push rod clevis
to brake pedal pin. Adjust pedal
height as indicated in paragraph
9-8.
3. Connect brake pipe to master
cylinder.
4. Connect vacuum hose to check
valve on power brake housing.
5. Bleed hydraulic system ac-
cording to procedure in paragraph
9-7.
J-7723-01
.010 MAX.
Figure 9-33—Gauging Master Cylinder Push Rod