STANDARD
BRAKES
5-13
4.
Remove small secondary piston
stop
bolt from
bottom of front fluid reservoir of master cylinder,
5. Place master cylinder in
soft
jaws of vise. Re-
move lock
ring
from small
groove
In inside diameter
of bore. Remove
primary
piston
(rear).
Remove
secondary (front) piston, piston spring and retainer
by applying air pressure through front
stop
bolt hole.
Do not attempt to disassemble front piston since
complete new assembly is provided in
repair
kit.
NOTE;
If air is not
available,
a
piece
of
wire
may
be
used.
Bend
one fourth
inch
of one end of
wire
into
right angle and hook end under edge
of
floating
piston
to remove.
6. For your convenience, in the event they are
needed,
repair
kits contain replacement check valves
and
springs. Following are the conditions under
which
the check valves should be replaced:
a.
Whenever fluid in brake system is
contaminated.
b.
Whenever foreign material or sediment is
found inside reservoir.
c.
If vehicle is 5 years old, or has
10,000
miles
or
more on it.
d.
If hydraulic brake master cylinder was sub-
jected to excessive heat such as fire due to
acci-
dent, etc.
NOTE:
In most
cases,
it
will
not be necessary to
install
new check valves unless conditions above
exist;
therefore, unless they do exist, it is not
recommended
that the check valves be replaced.
If
check valves do
require
replacement, carefully
follow
the
service
procedure
outlined below.
7.
With
master cylinder in vise (outlet
holes
up),
drill
out the tube fitting insert with a 13/64"
drill
and
then tap the hole, using a 1/4" x 20 tap. Place a
1/2" to 3/4" long, 1/4" x 20 bolt through a thick
washer
and then thread the bolt into the insert.
Tighten
the bolt against the washer until the insert
is removed.
8. Remove check valves and springs from cavities
beneath tube seats.
9. Remove master cylinder from vise and inspect
bore for corrosion, pits and foreign matter. Make
sure
outlet ports are clean and free of brass cuttings
from
tube-seat removal operation. Inspect fluid res-
ervoirs
for foreign matter.
Check
bypass and com-
pensating ports to master cylinder bore to insure
they are not restricted. Do not use wire to check
ports.
10. Remove
primary
seal,
primary
seal protector
and
secondary seals from front piston.
Cleaning
Use
a reputable cleaner or clean brake fluid to
clean
all metal brake parts thoroughly. Immerse
parts
in cleaning fluid using a bristle brush to re-
move foreign matter. Blow out all passages,
ori-
fices and valve holes. Air dry and place cleaned
parts
on clean paper or lintfree cloth.
NOTE:
Dirt
is the major cause of trouble and
wear
in
service.
Be
sure
to keep parts clean until
reassembly.
Rewash at reassembly if there is any
occasion
to doubt
cleanliness.
ASSEMBLE
1. Place master cylinder in vise, with outlet
holes
up.
Place check valve springs in outlet holes, so
they
will
seat in depression in bottom of holes.
Place
new rubber check valves over springs, being
careful
not to displace springs from their seat.
2.
Place new brass tube seat in outlet
holes
in
position to be pressed into outlet hole. Be sure that
it
is not cocked, as this would cause
burrs
to be
turned
up when the tube seat is pressed in. Recom-
mended method of inserting tube seat is to thread a
spare
brake line tube nut into outlet hole and
turn
nut
down until tube seat bottoms. (Remove tube nut and
check
outlet hole for
loose
burrs,
which might have
been turned up when the tube seat was pressed down.)
3.
Put new secondary seals in the two
grooves
in
the end of front piston. Seal which is nearest the end
of the piston
will
have its lips facing toward that end.
The
second
groove
seal should have its lips facing
toward
the portion of front piston which contains
small
compensating holes.
4. Assemble a new
primary
seal and protector
over end of front piston with flat side of seal seating
against seal protector and protector against flange of
piston which contains the small compensating
holes
(Fig.
5-6).
5. All master cylinder overhaul kits contain as-
sembled
primary
piston, making it unnecessary to
assemble any
primary
piston component parts.
6.
Coat
bore of master cylinder,
primary
and
secondary seals on front piston with clean brake
fluid.
Insert secondary piston spring retainer into
secondary piston spring. Place retainer and spring
down over end of front piston locating retainer inside
lips
of
primary
cup.
7. Holding master cylinder with open end of bore
down, push front piston into bore, seating spring
against closed end of bore.
8. Place master cylinder in vise with open end of
bore up.
Coat
primary
and secondary seal on
rear
piston with clean brake fluid. Push
rear
piston as-
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