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24
GROUP 2
BRAKES
#16
GAUGE
SHEET STEEL
H1208-A
FIG. 2-Push
Rod
Gauge Dimensions
correct
relationship
between
the
booster
control
valve plunger and
the
master
cylinder
piston.
Failure
to
maintain
this
relationship
will
pre
vent
the
master cylinder piston
from
completely releasing hydraulic
pres
sure
and
can
cause
the
brakes
to
drag.
To
check
the
adjustment
of
the
screw,
fabricate
a
gauge
of
the
di
mensions
shown
in
Fig.
2.
Then
ADJUSTMENT
SCREW
place
the
gauge
against
the
master
cylinder
mounting
surface
of
the
booster
body
as shown
in Fig. 3. The
push
rod
screw
should
be
adjusted
so
that
the
end
of
the
screw
just
touches the
inner
edge of
the
slot
in
the
gauge.
This is
an
approximate
adjust
ment only.
To
verify
the
adjustment,
look
through
the
make-up
(rear)
port when
installing
the
master
cylin
der
to the
booster. The
master cylin
der
piston
should
not
move
more
than
0.015
inch
as
it
contacts
the
push
rod.
No
movement
(exact
con
tact)
is ideal.
HYDRAULIC SYSTEM BLEEDING
When any
part
of
the
hydraulic
system
has
been
disconnected
for
repair
or
replacement,
air
may
get
into
the
lines
and cause
spongy
pedal
action.
Bleed
the
hydraulic
system
after
it has been properly
connected
to
be
sure
that
all air
is
expelled
from
the
brake
cylinders
and
lines.
The hydraulic
system can
be bled
manually
or
with
pressure
bleeding
equipment.
MANUAL
BLEEDING
Bleed
the
longest lines first.
Keep
the
master
cylinder
reservoir
filled
with
new
heavy-duty
brake fluid
dur
ing
the
bleeding
operation.
Never
use
brake
fluid
which
has
been drained from
the
hydraulic
system.
1. Position
a
bent
3/s-inch
box
wrench on
the
bleeder
fitting
on
the
right rear
brake
wheel cylinder
(Fig.
4).
Attach
a
rubber
drain
tube
to
the
bleeder fitting. The
end
of
the
tube
should
fit
snugly
around
the
bleeder fitting.
2. Submerge
the
free
end
of
the
tube
in
a
container
partially
filled
with
clean
brake
fluid,
and
loosen
the
bleeder
fitting
approximately
Va
turn.
3. Push
the
brake
pedal
down
slowly
thru
its
full
travel.
Close
the
bleeder
fitting,
then
return
the
pedal
to
the
fully-released
position.
APPROXIMATELY
45
Push Rod Gauge
FIG. 3-Push
Rod
Adjustment
H1209-A
HI
300-
A
FIG. 4-Wrench
for
Bleeding
Brake
Repeat
this
operation
until
air
bub
bles
cease
to
appear at
the
submerged
end of
the tube.
4. When
the
fluid
is
completely
free
of air
bubbles,
close
the
bleeder
fitting
and remove
the
drain
tube.
5. Repeat
this
procedure
at
each
brake
wheel
cylinder
in
order:
left
rear,
right
front,
and
left
front. Refill
the
master
cylinder
reservoir
after
each
brake
cylinder
is
bled
and when
the
bleeding
operation
is
completed.
The
fluid
level
should
be
within
%
inch
of
the
top
of
the
reservoir.
PRESSURE BLEEDING
Bleed
the
longest lines first. Never
use
brake fluid
which
has
been
drained from
the
hydraulic
system.
The bleeder
tank
should
contain
enough
new
heavy-duty
brake fluid
to
complete
the
bleeding
operation,
and
it
should
be
charged with
10-30
pounds
of
air
pressure.
1.
Clean
all
dirt from
the
master
cylinder
reservoir
cap.
2. Remove
the
master
cylinder
reservoir
cap,
install
an
adapter
cap
to
the
reservoir,
and
attach
the
bleeder
tank
hose
to
the
fitting
on
the
adapter cap.
Adapter cap 2162
can
be
used,
or
an
adapter
cap
can
be fabricated
by
cutting
a
hole in
the
center
of
a
reservoir
cap
and
soldering
a
fitting
at
the
hole.
3. Position
a
3/s-inch box
wrench
on
the
bleeder
fitting
on
the
right rear
brake
wheel
cylinder
(Fig. 4).
At
tach
a
rubber
drain
tube
to
the
bleeder fitting. The
end
of
the tube
should
fit
snugly
around
the
bleeder fitting.
4. Open
the
valve
on
the
bleeder
tank to
admit pressurized
brake fluid
to the
master
cylinder
reservoir.
5.
Submerge
the
free
end
of
the
tube
in
a
container
partially
filled
with
clean
brake
fluid,
and
loosen
the
bleeder
fitting.
6. When
air
bubbles
cease
to
ap
pear
in
the
fluid
at
the
submerged
end
of
the
drain
tube,
close
the
bleeder
fitting
and
remove
the tube.
7.
Repeat
this
procedure
at
each
brake
wheel
cylinder
in
order:
left
rear,
right
front,
and
left front.
8. When
the
bleeding
operation
is
completed,
close
the
bleeder
tank
valve and remove
the tank
hose from
the
adapter
fitting.
9.
Remove
the
adapter
cap,
refill
the
master
cylinder
reservoir
to
within
'/i
inch from
the
top
of
the
reservoir,
and
install
the
reservoir
cap.
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