2002 LAND ROVER DISCOVERY gearbox

MANUAL GEARBOX - R380
37-50 OVERHAUL
Reassembly
1.Using a suitable solvent cleaner, clean seal
housing mating faces.
2.Clean seal recess, bearings and bearing
races.
3.Lubricate new oil seal and fit using a suitable
mandrel into housing.
4.Fit input shaft front bearing track using a press
and suitable mandrel.
5.Apply sealant, Part No. STC 4404 to seal
housing, fit new bolts and tighten by diagonal
selection to 25 Nm (18 lbf.ft).
6.Clean clutch housing mating faces, dowels and
dowel holes.
7.Position clutch housing, fit bolts and tighten to
75 Nm (55 lbf.ft).
8.Clean release bearing sleeve mating faces,
dowel and dowel holes.
9.Position release bearing sleeve, fit bolts and
tighten to 25 Nm (18 lbf.ft).
10.Examine clutch release fork pivot points for
wear and replace as required.
11.Apply a smear of Molybdenum disulphide
grease to pivot points and position release fork.
12.Fit retaining clip ensuring it locates over pivot
point washer, fit bolt to release fork and tighten
to 10 Nm (7 lbf.ft).
13.Clean release bearing and bearing sleeve
mating faces.
14.Apply smear of Molybdenum disulphide grease
to release bearing sleeve.
15.Fit release bearing and secure with retaining
peg.

TRANSFER BOX - LT230SE
41-4 DESCRIPTION AND OPERATION
Main casing components – Vehicles up
to 03 model year
1Retaining plate
2Stake nut - intermediate shaft
3Bolt - retaining plate
4'O' rings - intermediate shaft
5Bearings and outer tracks - mainshaft input
gear
6Mainshaft input gear bearing housing
7Cover plate
8Bolt - cover plate
9Selective shim
10Mainshaft input gear
11Oil filler/level plug
12Oil temperature switch - if fitted
13Bearings and outer tracks - intermediate gears
14Circlips
15Intermediate gears
16Bottom cover plate
17Bolt - bottom cover plate
18Selective spacer
19Mainshaft oil seal20Oil drain plug
21Main casing
22Intermediate shaft
23Locating dowel
24Detent ball - high/low selector
25Detent spring - high/low selector
26Detent plug - high/low selector
27Neutral warning switch - Automatic gearbox
only - North America and Japan
28Bolt - interlock solenoid cover - Automatic
gearbox only - North America and Japan
29Cover - interlock solenoid - Automatic gearbox
only - North America and Japan
30Belleville washer - Automatic gearbox only -
North America and Japan
31Interlock solenoid - Automatic gearbox only -
North America and Japan

TRANSFER BOX - LT230SE
DESCRIPTION AND OPERATION 41-5
Main casing components – Vehicles
from 03 model year
1Retaining plate
2Stake nut - intermediate shaft
3Bolt - retaining plate
4'O' rings - intermediate shaft
5Bearings and outer tracks - mainshaft input
gear
6Mainshaft input gear bearing housing
7Cover plate
8Bolt - cover plate
9Selective shim
10Mainshaft input gear
11Oil filler/level plug
12Oil temperature switch - if fitted
13Bearings and outer tracks - intermediate gears14Intermediate gears
15Bottom cover plate
16Bolt - bottom cover plate
17Selective spacer
18Mainshaft oil seal
19Oil drain plug
20Main casing
21Intermediate shaft
22Locating dowel
23Detent ball - high/low selector
24Detent spring - high/low selector
25Detent plug - high/low selector
26Neutral warning switch - Automatic gearbox
only - North America and Japan

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
41-20 DESCRIPTION AND OPERATION
Power flow - transfer box in HIGH ratio
Up to 03 Model Year section shown, from 03MY similar
The gearbox output shaft transmits power to the mainshaft input gear which is in constant mesh with one of the
intermediate gears. The intermediate gears are in constant mesh with the high and low range output gears running
on the differential rear shaft.
Power is transmitted to the output shafts via the differential assembly by locking either the high or low range gears to
the differential rear shaft. This is achieved by means of the high/low selector fork, sleeve and splined hub.

TRANSFER BOX - LT230SE
ADJUSTMENTS 41-21
ADJUST ME NTS
Cable - high/low selector
$% 41.20.46
Adjust
1.Raise vehicle on ramp.
2.Using a suitable crows foot spanner, loosen
lock nuts securing outer cable to abutment
bracket.
3.Select high range by moving lever on transfer
gearbox fully forward.
4.Insert tool LRT-41-016 through hole in selector
lever and housing. This ensures selector
lever is in the high range position.
5.Lightly tighten outer cable lock nuts.
6.Remove tool LRT-41-016 from gear selector
lever and housing.
7.Simultaneously tighten high/low selector cable
lock nuts either side of abutment bracket to 30
Nm (22 lbf.ft) .
8.Lower vehicle on ramp.