Buick LeSabre 1965 Service Manual page 544

9 - 2 2 MASTER CYLINDER BRAKES
COMPENSATING
PORT
RESERVOIR COVER
RETAINING BAIL
RESERVOIR COVER
RUBBER DIAPHRAGM
BREATHER PORT
PISTON
PISTON SPRING
& RETAINER
RUBBER
BOOT
PUSH ROD
PORTS
VALVE WASHER
SEAT PRIMARY CUP
LOCK RING
SECONDARY CUP
"bearingized" surface produced
by diamond boring followed by
rolling under very heavy pres-
sure. Honing destroys the bear-
ingized surface, leaving a softer
and rougher surface which will
cause more rapid wear of pistons
and rubber cups. Higher friction
produced by the rougher surface
will also reduce braking power
for a given pressure on brake
pedal.
The maximum allowable clear-
ance between piston and cylinder
bore is .0055". If this clearance
is increased by honing, the heavy
pressure of brake fluid may force
rubber of the cup into the clear-
ance and cause sticking or early
failure of the cup. If a choice
must be made between honing or
replacement of the cylinder, it
must be remembered that while a
new cylinder may be more ex-
Figure 9-14—Standard Brake Master Cylinder
pensive a honed cylinder may not
give s a t i s f a c t o r y length of
service.
e. Installation of Brake
Master Cylinder
d. Assembly of Brake Master
Cylinder
1. Dip all internal parts in clean
brake fluid just before installa-
tion. Also wet master cylinder
bore with brake fluid.
2. Install v a l v e seat washer,
check valve, spring, primary cup,
and piston with secondary cup.
Then install push rod and stop
plate assembly. Hold push rod in
and install lock ring. Check for
proper seating of lock ring with a
hard pull on push rod.
3. Install rubber boot. Check
filler cap holes to make sure they
are clear, then install rubber
diaphragm, cap and bail.
1. Install master cylinder on dash
panel. Torque nut to 20-28 ft. lbs.
2. Connect push rod to brake
pedal by installing spring washer,
shoulder bolt and locknut.
3. Connect brake pipe to master
cylinder.
4. Bleed hydraulic system as de-
scribed in paragraph 9-6. Bleed
left front wheel cylinder first and
check for proper pedal feel. If
system still has air in it, bleed
other three wheel cylinders. After
bleeding, bring fluid to 1/8" below
lip of reservoir opening.
5. Check brake pedal for full re-
turn and check stop light switch
adjustment as described in para-
graph 9-7 (b).
6. Road test car for proper brake
performance (par. 9-4).