differential LAND ROVER DISCOVERY 2002 Owner's Manual

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-3
1Rear output housing
2Differential rear bearing
3High range gear and bush
4Main casing
5High/low selector sleeve and hub
6Low range gear
7Differential assembly
8Front output housing
9Differential front bearing
10Selective shim - differential bearing pre-load
11Dog clutch - Differential lock - If fitted
12Front output flange
13Differential lock selector shaft - Differential lock
- If fitted
14Selector fork - Differential lock - If fitted
15Front output shaft
16Selective spacer - intermediate gear bearing
pre-load
17Mainshaft input gear
18Selective shim - input gear bearing pre-load
19Intermediate shaft
20Intermediate gear cluster
21Rear output shaft
22Rear output flange

TRANSFER BOX - LT230SE
41-6 DESCRIPTION AND OPERATION
Differential components – Vehicles up to
03 model year
1Retaining ring
2Differential carrier - rear half
3Low range gear
4High/low hub
5High/low selector sleeve
6High/low selector shaft
7High/low selector fork
8Setscrew - high/low selector fork
9High range gear
10High range gear bush
11Differential rear bearing
12Bearing outer track13Bearing retaining nut
14Dished thrust washers
15Planet gears
16Cross shafts
17Sun gears
18Selective thrust washers
19Differential carrier - front half
20Bolt - differential carriers
21Differential front bearings
22Bearing outer track
23Selective shim

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-7
Differential components – Vehicles from
03 model year
1Retaining ring
2Differential carrier - rear half
3Low range gear
4High/low hub
5High/low selector sleeve
6High/low selector shaft
7High/low selector fork
8Clip (2 off)
9Spring
10Setscrew - high/low selector fork
11High range gear
12High range gear bush
13Differential rear bearing14Bearing outer track
15Bearing retaining nut
16Dished thrust washers
17Planet gears
18Cross shafts
19Sun gears
20Selective thrust washers
21Differential carrier - front half
22Bolt - differential carriers
23Differential front bearings
24Bearing outer track
25Selective shim

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-9
1Breather pipe, banjo bolt and sealing washers
2Bolt - high/low cross shaft housing and
abutment bracket
3Selector cable abutment bracket
4Multiplug bracket
5Hollow plug
6High/low cross shaft housing
7'O' ring
8High/low cross shaft and lever
9Front output shaft - Differential lock - If fitted
10Dog clutch - Differential lock - If fitted
11Warning lamp switch - Differential lock - If fitted
12Detent plug - Differential lock - If fitted
13Detent spring - Differential lock - If fitted
14Selector shaft - Differential lock - If fitted
15Detent ball - Differential lock - If fitted
16Threaded spacer - Differential lock - If fitted
17Front output housing
18Spring and clips - Differential lock - If fitted
19Bolt - cover plate
20Cover plate21Selector fork - Differential lock - If fitted
22Bolt - front output housing
23Hollow plug
24Circlip
25Front output flange
26Steel washer
27Self-locking nut
28Felt washer
29Oil seal
30Output shaft bearing
31Bearing spacer
32High/low detect switch
33Selector finger and shaft - Differential lock - If
fitted
34'O' rings - Differential lock - If fitted
35Bolt - selector housing - Differential lock - If
fitted
36Selector housing - Differential lock - If fitted
37High/low selector finger
38Front output shaft - Vehicles not fitted with
differential lock

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-11
1Breather pipe, banjo bolt and sealing washers
2Bolt - high/low cross shaft housing and
abutment bracket
3Selector cable abutment bracket
4Multiplug bracket
5Hollow plug
6High/low cross shaft housing
7'O' ring
8High/low cross shaft and lever
9Front output shaft - Differential lock - If fitted
10Dog clutch - Differential lock - If fitted
11Warning lamp switch - Differential lock - If fitted
12Detent plug - Differential lock - If fitted
13Detent spring - Differential lock - If fitted
14Selector shaft - Differential lock - If fitted
15Detent ball - Differential lock - If fitted
16Threaded spacer - Differential lock - If fitted
17Front output housing
18Spring and clips - Differential lock - If fitted
19Bolt - cover plate
20Cover plate
21Selector fork - Differential lock - If fitted
22Bolt - front output housing23Aluminium washer
24Warning lamp switch - Differential lock - If fitted
25Circlip
26Front output flange
27Steel washer
28Self-locking nut
29Felt washer
30Oil seal
31Output shaft bearing
32Bearing spacer
33High/low detect switch
34Selector finger and shaft - Differential lock - If
fitted
35'O' rings - Differential lock - If fitted
36Bolt - selector housing - Differential lock - If
fitted
37Selector housing - Differential lock - If fitted
38High/low selector finger
39Front output shaft - Vehicles not fitted with
differential lock
40Washer
41Nut

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-13
Description
General
The LT 230SE transfer box is mounted at the rear of the gearbox and transmits drive via high or low reduction ratios
to the front and rear axles via the propeller shafts. The high/low ratios are 1.211:1 and 3.32:1 respectively.
Transfer boxes fitted to this model have the prefixes 41D and 42D to the unit serial number. Prefix 41D denotes that
the unit is not fitted with interlock whilst 42D denotes that interlock is fitted.
Vehicles up to 03 model year – Whilst similar to LT230Q transfer boxes fitted to other models, the LT230SE transfer
box has certain engineering modifications incorporated which are as follows:
lUprated torque capacity
lModified front and rear output and cross shaft housings
lIntermediate gear bearing pre-load now controlled by a selective, non-collapsible spacer
lSpeedometer drive and driven gears not fitted for this application
lModified high/low sleeve
lModified front output flange and mud shield
lDifferential lock fitted to certain vehicles, but no longer driver operated
lFixed setting of differential lock warning lamp switch on vehicles fitted with differential lock
Vehicles from 03 model year – The LT230SE transfer box is as described above for vehicles up to 03 model year
with the following modifications:
The following items are introduced on vehicles from 03 model year
lRibs added to main casing to reduce operating noise
lBearing retaining nut on the differential carrier has patchlock added to the threads
lInterlock solenoid moved from main casing to selector lever assembly
lIntermediate gears modified with machined internal shoulder and bearing circlips deleted
The following items are introduced later in the 03 model year build programme and therefore may not appear on all
03 model year vehicles
lDriver operated differential lock (if fitted)
lHigh/Low selector shaft fitted with spring assist
lExisting differential lock switch replaced by new design switch.
lNew secondary differential lock switch installed in the front output housing
Construction
The transfer box comprises three main assemblies; the main casing, the front output housing and the rear output
housing. Both output housings and all cover plates are sealed to the main casing by sealant; mud and water ingress
being prevented by mud shields located on the output flanges.
Main casing
The main casing carries the mainshaft input gear, the intermediate gears and the differential, together with the high/
low range gears, selector shaft and fork. The front and rear output housings are bolted to either side of the main
casing.
Transmission neutral sensor
A transmission neutral sensor is fitted on automatic gearbox vehicles for North America and Japan. The sensor is
connected to the BCU and is normally in the open position. The sensor provides an earth path for the BCU which then
interprets the signal and activates an audible warning generated by the IDM if neutral is selected on the transfer box
when the ignition is on.

TRANSFER BOX - LT230SE
41-14 DESCRIPTION AND OPERATION
Transfer box interlock solenoid - Automatic gearbox vehicles
An interlock solenoid is fitted for North America and Japan. The solenoid is located on the top of the transfer box main
casing on vehicles up to 03 model year or on the selector lever assembly on vehicles from 03 model year. The
solenoid is connected to the transfer box relay which, in turn, is controlled by the IDM. The purpose of the solenoid is
to prevent neutral being selected on the transfer box when the ignition key is removed, thereby locking the box in
either high or low ratio.
Mainshaft input gear
The gearbox output shaft is splined into the mainshaft input gear which is supported by taper roller bearings.
Input gear bearing pre-load is achieved by the use of a selective shim located in the bearing housing.
Intermediate gears
The intermediate gear cluster is supported by the taper roller bearings located at each end of the cluster and runs on
the intermediate shaft which, in turn, is supported at the front and rear by the main casing.
A selective spacer, positioned between the gears, pre-loads the intermediate gear bearings when the intermediate
shaft nut is tightened sufficiently to achieve the correct 'torque to turn' of the intermediate gears.
On vehicles from 03 model year, the circlips used to retain the bearings in the intermediate gear are deleted. The bore
of the intermediate gear is machined with a shoulder at each end to locate the bearings.
Differential assembly
The differential assembly is supported at the front and rear by taper roller bearings, the front bearing outer track is
located in the front output housing and the rear bearing outer track is located in the main casing by the rear output
housing. Bearing pre-load is achieved by means of a selective shim located in the front output housing.
The differential rear shaft carries the low range gear, high/low selector sleeve and hub, high range gear and bush and
the differential rear bearing; these components being secured to the shaft by a special staked nut.
The differential assembly comprises front and rear half carriers with integral shafts and with sun and planet gears
mounted on cross shafts within the half carriers. Dished, non-selective thrust washers control the engagement of the
planet gears with the sun gears, whilst selective thrust washers are used to control engagement of the sun gears and
'torque to turn' of the differential. The differential carrier halves are bolted together, a retaining ring providing positive
location of the cross shafts.
The high/low selector shaft and fork are located at the side of the differential, movement of the shaft, fork and selector
sleeve being controlled by the high/low selector finger. A spring loaded detent ball fitted in the main casing, locates
in grooves in the shaft.
On vehicles from 03 model year, the selector fork is modified and fitted with a spring assistor and clips to reduce the
effort required to move the selector lever.
Front output housing
The front output housing carries the front output shaft and flange, high/low cross shaft, housing and selector and on
certain vehicles, the differential lock selector shaft and fork.
The front output shaft is supported in the housing by a single bearing and is splined into the differential front sun gear.
High/low selector
The high/low cross shaft is located in a housing bolted to the top of the output housing and is connected to the high/
low selector finger which locates in a slot in the selector shaft.

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-15
High/low detect switch
A high/low detect switch is fitted in the front output housing and connects to earth when low is selected. The switch is
connected to the engine ECM, the SLABS ECU and the EAT ECU. The purpose of the switch is to enable selection
of the hill descent feature and to modify the engine fuelling and automatic gearbox gearshift maps stored within the
respective ECM's and ECU's.
Differential lock - Fitted to certain vehicles only
The differential lock selector housing is bolted to the top of the front output housing, the selector finger passes through
the housing, locating in a slot in the differential lock selector shaft. The differential lock selector shaft passes through
the selector fork which is located beneath a plate bolted to the side of the output housing. The selector fork engages
the dog clutch sleeve with the differential rear shaft when the splines of the sleeve and differential rear shaft are
aligned. A spring loaded detent ball fitted in the output housing locates in grooves in the shaft.
Functionality – Vehicles up to 03 model year only
The function of the differential lock used in previous applications is performed on this vehicle by the Electronic Traction
Control System. However, for the purposes of 2 wheel rolling road testing , the differential lock components are
retained. For all driving conditions however, the differential lock must be set in the unlocked position.
Up to 03 model year specification shown
The differential lock must only be engaged for 2 wheel rolling road testing as engagement of the lock disables the
traction control feature and inhibits correct operation of the electronic brake distribution and hill descent features. It
will also be necessary to disconnect the propeller shaft from the transfer box output shaft driving the axle whose
wheels are NOT on the rolling road. The lock may be engaged/disengaged by using a 10 mm open ended spanner
on the flats (arrowed) machined on the differential lock selector shaft.
Vehicles not fitted with a differential lock may be identified by there being no cover or selector shaft (arrowed) on the
front output housing.
WARNING: VEHICLES NOT FITTED WITH A DIFFERENTIAL LOCK MUST NOT BE TESTED ON A ROLLING
ROAD WHERE THE ROLLERS ARE DRIVEN BY THE VEHICLE.

TRANSFER BOX - LT230SE
41-16 DESCRIPTION AND OPERATION
Functionality – Vehicles from 03 model year only
The differential lock must be engaged for 2 wheel rolling road testing. It will also be necessary to disconnect the
propeller shaft from the transfer box output shaft driving the axle whose wheels are NOT on the rolling road. In
addition, the ETC system must be deactivated by either, removing a fuse (10A fuse 28 in the passenger compartment
fusebox, labelled ABS) or disconnecting the ABS modulator pump. This must be done with the ignition switched off.
Note that the SLABS ECU may record a system fault.
The lock can be engaged or disengaged using the selector lever. Vehicles not fitted with a differential lock can be
identified by a high/low range selector lever with no differential lock functionality and the cover and selector shaft
(arrowed), not visible on the front output housing.
WARNING: VEHICLES NOT FITTED WITH A DIFFERENTIAL LOCK MUST NOT BE TESTED ON A ROLLING
ROAD WHERE THE ROLLERS ARE DRIVEN BY THE VEHICLE.
Differential lock warning lamp switch - if fitted - Vehicles up to 03 model year
A differential lock warning lamp switch connected to the SLABS ECU and operated by movement of the selector fork
and shaft is screwed into the top of the output housing. The switch connects to earth when the differential lock is
engaged.
Differential lock warning lamp switches - if fitted - Vehicles from 03 model year
Vehicles from 03 model year are fitted with two differential lock warning lamp switches.
One switch is of a new design and is fitted into the top of the front output housing in the same position as on previous
models. The switch is connected to the SLABS ECU and is operated by movement of the selector fork and shaft.
The second switch is located in a threaded hole on the forward face of the front output housing. The switch is also
connected to the SLABS ECU and is operated by movement of the selector shaft.
Both switches have an aluminium washer which seals the switch to the casing and also sets the switch position,
removing the requirement for a setting procedure.
Both switches are connected in parallel to earth when the differential lock is engaged. This earth is sensed by the
SLABS ECU which illuminates the differential lock warning lamp in the instrument pack.
Differential lock warning lamp - Vehicles up to 03 model year – if fitted
The differential lock warning lamp is located in the instrument pack and provides a warning to the driver when the
ignition is switched on that the differential lock is engaged. The warning lamp illuminates in a Red colour.
With the lock engaged, the traction control and electronic brake distribution warning lamps will also be illuminated.
Disengagement of the differential lock should be carried out with the ignition switched off. The warning lamps must
be extinguished when the ignition is switched on again.
Differential lock warning lamp – vehicles from 03 model year – if fitted
The differential lock warning lamp is located in the instrument pack and provides a visual warning to the driver, when
the ignition is on, the differential lock is engaged. The warning lamp illuminates in an amber colour.
When the lock is engaged, the warning lamp is illuminated and the instrument pack sounder emits three audible
chimes. When the lock is disengaged, the warning lamp is extinguished and the instrument pack sounder emits three
audible chimes.
Rear output housing
The rear output housing carries the output shaft and flange. A cable operated transmission brake is attached to the
housing, the brake drum being attached to the output flange.
The rear output shaft is supported in the housing by a single bearing and is splined into the differential rear sun gear.

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-17
Lubrication
Lubrication is by splash, oil filler/level and drain plugs being located in the main casing.
Internal pressures caused by thermal expansion and contraction are avoided by the use of a plastic breather pipe
venting the interior of the box to atmosphere. The pipe is attached to the top of the high/low selector housing by a
banjo bolt and is then routed in a continuously rising path into the engine compartment where the open end is secured
by a clip attached to the engine cylinder block.
Oil temperature warning lamp switch
An oil temperature switch is fitted to V8 engine models. In the event of the transfer box oil approaching maximum
recommended working temperature of 145
°C (293°F), the switch will close and a warning lamp in the instrument pack
will be illuminated.
High/Low range and differential lock selector lever assembly – Vehicles from 03 model year
1Selector lever
2High/Low range cable
3Differential lock cable
4Interlock solenoid