MG MGB User Manual

THE
OVERDRIVE
Fa
Section
F 3.1 1
DRIVE
SHAFT
BEARINGS
AND
SEAL
Removing
The drive
shaft front
bearing
must
be drawn
from
the
shaft
with
a
suitable
puller.
The
oil seal
may
be
removed
with the
overdrive
in
position
in
the
car
after
removing the
propeller
shaft
and
drive
■ange.
The
rear
bearing
should
be
pressed from
its
seating with
a
suitable
spigot.
Replacing
A
press
should
be
used when
replacing
the
bearings.
Fit
a
new
oil
seal.
Section
Fa. l
2
OVERDRIVE
RELAY
SYSTEM
Description
Engagement
of
overdrive
is
controlled
electrically
through
a
manually
operated
toggle
switch.
The
circuit
is shown
in
Fig.
F
a.10 and
includes
the
following
components:
1. RELAY.
An
electro-magnetic
switch
used
with
item
2
to
enable
an
interlocking
safeguard
to
be
incorporated
against changing
out
of
overdrive
with
the
throttle
closed.
.
2. THROTTLE
SWITCH.
A
vacuum-operated
switch
to
over-ride the
toggle
switch
under
closed
throttle
conditions.
3. GEAR
SWITCH.
A
small
plunger-operated
switch
allowing
overdrive
to
be
engaged
only
in the
two
highest
forward
gear
positions.
4. SOLENOID
UNIT.
An electro-magnetic
actuator
to
engage
the
overdrive
mechanism
by
opening the
hydraulic
control
valve.
Operation
When
the
driver
engages
‘overdrive’
by
closing
the
contacts
of
the
toggle
switch,
current
is
fed
by
way
of
the
ignition
switch
and fuse
unit supply
terminal
‘A3’
to energize the
relay
operating coil.
Closure
of
the
relay
contacts
connects
MGB.
Issue4.
15676
terminal
‘A3’
to
the
gear
switch
and,
provided
third
or
top
gear
is
engaged,
will
energize
the
solenoid
unit
and effect
a
change
from
direct
drive
to
overdrive.
Change
from
overdrive
to
direct
drive
is effected
by
selecting
a
low
gear
(when
the
gear
switch
contact
will
open)
or
by
moving the
toggle
switch
to
‘NORMAL’
with
the
throttle
open
(when
the
vacuum
switch
will open).
If
effected
with
the
throttle
closed
(high
manifold
depression)
the
vacuum
switch
will
over-ride
the
toggle
switch,
delaying
the
change
until the
engine takes
up
the
drive.
4
7
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E
F)
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Y
w
6
I
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A9266
Fig.
Fa.
lO
Diagram
of
the
overdrive
electrical
circuit
1.
Fuse
block.
5. Relay.
2.
Ignition
switch.
6.
Gearbox
switch.
3.
Driver’s
switch.
7.
Solenoid.
4.
Vacuum
switch.
CABLE
COLOUR
CODE
When
a
cable
has
two
colour
code
letters
the
first
denotes
the
main
colour
and the
second
denotes
the
tracer colour.
P. Purple.
R.
Red.
W.
White.
Y. Yellow.
Fa.11

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English