MG MGB User Manual

THE
BRAKING
SYSTEM
M
Section
M3
HAND
BRAKE
The
hand
brake,
which
is
of the
lever
type,
incorporating
a
thumb-operated
ratchet
release
in
the
handle,
is
located
on
the
right-hand
side
of
the
■oor
tunnel
between
the
seats.
Pulling
the
handle
operates
the
rear
shoes
only by
means
of
cable-operated levers,
The action
of the
inner
and
outer
cables
is
employed
through
the
action
of
a
balance lever
mounted
on
the
rear
axle
to
ensure
even
braking
on
the
rear
wheels.
Adjustment
of
the
rear
brake-shoes
automatically
adjusts
the
hand
brake,
but excessive
movement
of the
hand
brake
lever
due
to
cable
stretch
should
be taken
up
as
follows.
Adjust
the
inner
cable
length
by turning
the
brass
adjusting
nut at
the lower
end
of the
hand
brake
lever
below
the
car
■oor.
The
adjustment is
correct
if the
hand
brake
is
applied
fully
when
the lever is
pulled
up
three
or
four
notches.
The
rear
brake-shoes
should
be
adjusted
as
described
in
Section
M.1
before
taking
up
the
hand
brake
cable
stretch.
To
remove
(lever
and cable
assembly)
Unscrew
and
remove
the
adjusting
nut,
withdraw
the
end
of
the
cable
from
the lower
end
of the
lever,
and
remove
the
Spring
and
■at
washers.
Remove
the
nut
securing
the
brake lever
to
the
hand
brake
spindle
and
withdraw
the spring
washer,
forked
lever,
and
plain
washer.
The
hand lever
may
now
be
withdrawn
from
inside
the
car.
'
Remove
the
right-hand
seat
(see Section
R). Unscrew
the
three
screws
securing
the
ratchet
plate
to
the
■oor
tunnel.
Lift
the
carpet
and
remove
the
nut
and
spring
washer
securing
the
outer
cable
front
abutment.
Disconnect
the
clips securing
the
cable
assembly
to
the
body
and
rear
axle.
Remove
the
bolt,
nut,
and
spring
washer
connecting
the
two
halves
of
the brake
compensating
lever
to
each other,
slacken
fully
the
self-locking
nut
securing
the
lever
to
the
axle
bracket,
and
release
the
cable abutment
trunnion
from
the lever,
Extract
the
split pins
and
withdraw
the
clevis pins
to
release
the
cable
yokes
from
the levers
on
the
brake
backplates.
On
replacement,
check the
hand
brake lever operation
as
detailed above.
’
Section
M.4
BLEEDING
THE
BRAKE
SYSTEM
The
following
procedure
should
be
adopted
either
for
initial
priming
of the
system
or
to
bleed
in
service
if
air
has
been
permitted
to
enter
the
system.
Air
may
enter
the
system
if
pipe
connections
become
loose
or
if the
level
of
■uid
in
the reservoir
is
allowed
to
fall
below
the
recommended
level. During
the
bleeding
operation
it is
important
to
keep
the reservoir
at
least
half-full
to
avoid
drawing air into
the
system.
MGB.
Issue4. 69615
Check
that
all connections
are
tightened
and
all bleed
screws
closed.
Fill
the
■uid reservoir
with
the
recommended
■uid
(see
‘GENERAL
DATA’).
Keep it
at
least
half-full
throughout
the
bleeding operation,
otherwise
air
will
be drawn
into
the
system,
necessitating
a
fresh
start.
Attach the
bleeder
tube
to
the
bleed
screw
on
the near-side
rear
brake
and
immerse
the
open
end of the
tube
in
a
small
quantity
of brake
■uid
contained
in
a
clean
glass
jar.
Slacken
the
bleed
screw
and depress
the brake
pedal slowly
through
its
full
stroke
and
allow
it
to
return
without
assistance.
Repeat
this pumping
action
with
a
slight
pause
before
each depression
of the
pedal.
When
■uid entering
the jar is
completely
free
of
air
bubbles
hold
the
pedal
firmly
against
the
■oorboards
and
tighten
the
bleeder
screw.
This
process
must
be
repeated
at
each
of
the three
remaining
brake
assemblies.
Top
up
the
■uid reservoir
to
its
correct
level■in.
(6.35
mm.) below the
filler
neck.
If the
disc brake
callipers
have been
disturbed
it
will be
necessary
to
pump
the
brake
pedal
several
times
to
restore
the automatic
adjustment
of
the friction
pads.
Apply
a
normal working
load
on
the
brake
pedal
for
a
period
of
two
or
three
minutes
and
examine
the entire
system
for leaks.
Section
M.5
MASTER
CYLINDER
Description
The
master
cylinder
piston
is
backed by
a
rubber
cup
normally
held
in
the
‘off’
position
by
a
piston
return
spring.
Immediately
in
front
of the
cup,
when
it
is
in
the
‘off’
position, is
a
compensating
ori■ce connecting
the
cylinder
with the
■uid
supply. Pressure
is
applied
to
the
piston
by
means
of the
push-rod
attached
to
the brake
pedal.
The
reduced skirt
of the
piston
forms
an
annular
space
7
Fig.
M.2
The
upper arrow
showsthe
brake
master
cylinder
filler
cap
M.3

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English