MG MGB User Manual

F
THE
GEARBOX
GENERAL DESCRIPTION
The gearbox has
four forward
gears
and
a reverse
gear;Top,
third, and
second
gear
engagement
are
effected
by
synchromesh hubs
with direct
drive
for
top
gear
and
constant-mesh
gears on
the layshaft
and mainshaft for
third
and second
gears.
First
and
reverse
gears are
sliding
spur
gears.
A combined dipstick
and
■ller
plug
is
housed
in
the
top
of
the
gearbox and
a
drain
plug
in
the bottom.
The bell
housing
is
integral with the
gearbox
and
accommodates
the clutch release mechanism
and the
starter
motor
driving
pinion.
An
extension
bolted
to
the
rear
end
of
the
gearbox
contains
the
gear
selector mechanism.
The
gearbox
is
bolted
at
the front
end
to
the
engine
mounting
plate
and
is
supported
at
the
rear
by
two
rubber
mountings
that
locate
on
the
rear
cross-member
mounting
brackets.
An
engine
stay-rod attached
to
the
under
side
of
the
rear
extension is
anchored
to
the
rear
cross-member.
LUBRICATION
Oil
level
When
topping
up
the gearbox
ensure
that
it is
not
■lled
above the ‘HIGH’
mark
on
the
dipstick.
1f
the level
is
too
high,
oil
may
get
into
the
clutch
case
and
cause
clutch slip.
The combined filler
plug
and dipstick for
the
gearbox and
overdrive
is
located beneath the
rubber plug
on
the
gearbox
cover.
Draining
Remove the
gearbox drain plug
and drain off
the oil.
When
the gearbox
has been
drained,
completely re■ll
with
fresh
oil.
Section
F.1
REMOVING THE
GEARBOX
1.
Prepare the
engine
for
removal from
the
car as
detailed
in Section A and
take
the
weight of
the
,
engine.
Drain
the
oil from
the
gearbox.
3.
Disconnect and
remove
the
propeller shaft
as
detailed
in
Section G and disconnect
the
speedometer
pinion
drive.
4. Disconnect the clutch
slave cylinder
push-rod from
the clutch
withdrawal
lever
and the
slave cylinder
from the
clutch housing.
Tie the
cylinder
clear of
the
gearbox.
5. Remove
the
screws
securing
the
rear
cross-member
to
the body and
lower the
engine
and
gearbox
until the
gearbox
rests
on
the ■xed
body
cross-member.
6.
.Release
the
engine
stay-rod bracket
from
the
rear
cross-member
and
remove
the
four
nuts
and washers
securing
the
gearbox
rear
rubber
mountings
to
the
cross-member. Withdraw the
rear
cross-member
from
the body.
5"
F.4
7. Remove the
gear
lever knob
and the
rubber
cover
from
the
tunnel.
Remove the
remote-control
tower
complete
with
gear
lever from
the
gearbox.
8. Ease the
assembly forward
until
it is
clear of the fixed
body
cross-member
and
then
tilt the
assembly
and lift
it
from
the
car.
C
9. Remove the
screws
securing
the
gearbox
to
the
engine
rear
mounting
plate
and
separate
the
gearbox
from
the
engine.
NOTE—Great
care
must
be taken
during
this
operation
to
ensure
that
no
load
is placed
on
the
clutch
release
plate
drive
straps.
Even slight
damage
to
these
may
result
in the clutch
breaking
up
at
high
speeds.
10.
Remove the stiffnut
and washer from
the
clutch
withdrawal
lever bolt
and take
the
dust
cover
and
lever
from
the
clutch housing.
11.
Remove the
nut,
spring
washer,
and
pin
from
the
engine
stay-rod
and the
stay-rod
from
the
gearbox.
12.
If
the
stay-rod
and bracket
are
to
be dismantled
remove
the
rear
nut
and
washer and slide off
the
plates,
buffers, brackets, and distance tube.
Separate
the plates,
buffers, and brackets from
the distance
tube.
Section
F .2
DISMANTLING
THE GEARBOX
1.
Remove
the dipstick,
drain plug,
and
speedometer
drive
pinion.
2. Using
Service
tool
18G
2,
remove
the
propeller
shaft
■ange.
3.
Remove
the
remote-control
tower,
the
gearbox
extension side
cover,
and
the
interlock
plate
and
bracket.
4.
Slacken the
locating
screw
on
the
remote-control
front
selector
lever,
unscrew
the
screws
and
nuts
securing
the
extension
to
the
gearbox,
and
remove
the
extension.
5.
Retain
the
remote-control
selector
lever, which
will
fall
free
as
the
extension is
withdrawn.
Withdraw
the
shaft
and
rear
selector
lever
from
the
rear
extension
and
remove
the
selector
lever from
the shaft;
withdraw
the
split
bush
and circlip from
the
selector.
6.
Remove the three
countersunk
screws
and
seven
hexagon-headed
screws
from
the
gearbox
side
cover
and lift off
the
cover
and gasket.
7. Cut the
locking
wire,
unscrew
the three
selector
locating
screws,
and
remove
the selectors.
8. Unscrew
the
shift
shaft
locating
block
screws
and
remove
the
block
from
the
rear
face
of the
gearbox.
Retain the
three
balls
and
springs which
will be
released
when
the
block
is
withdrawn from
the
shafts.
Two dowels
on
the
block locate
it
on
the
rear
face of
the
gearbox.
9. Release
the
locknuts
and
remove
the fork
locating
screws
and
star
washers from
the change
speed
forks.
MGB.
Issue4.
5335

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English