Discovery 2. Manual — part 127

TRANSFER BOX - LT230SE

DESCRIPTION AND OPERATION

41-11

1 Breather pipe, banjo bolt and sealing washers
2 Bolt - high/low cross shaft housing and

abutment bracket

3 Selector cable abutment bracket
4 Multiplug bracket
5 Hollow plug
6 High/low cross shaft housing
7 'O' ring
8 High/low cross shaft and lever
9 Front output shaft

10 Dog clutch - Differential lock
11 Warning lamp switch - Differential lock
12 Warning lamp switch - Differential lock
13 Aluminium sealing washers
14 Selector shaft - Differential lock
15 Aluminium sealing washer
16 Front output housing
17 Spring and clips - Differential lock
18 Bolt - cover plate
19 Cover plate
20 Selector fork - Differential lock
21 Bolt - front output housing

22 Detent plug - Differential lock
23 Detent spring - Differential lock
24 Detent ball - Differential lock
25 Hollow plug
26 Circlip
27 Front output flange
28 Steel washer
29 Self-locking nut
30 Felt washer
31 Oil seal
32 Output shaft bearing
33 Bearing spacer
34 High/low detect switch
35 Selector finger and shaft - Differential lock
36 'O' rings - Differential lock
37 Bolt - selector housing - Differential lock
38 Selector housing - Differential lock
39 High/low selector finger
40 Washer
41 Nut
42 Differential lock selector lever

TRANSFER BOX - LT230SE

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DESCRIPTION AND OPERATION

Rear output housing components

1 Rear output shaft
2 Rear output housing
3 Bolt - rear output housing
4 Spacer
5 Output shaft bearing
6 Circlip

7 Oil seal
8 Mud shield
9 Rear output flange

10 Felt washer
11 Steel washer
12 Self-locking nut

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:

l

Uprated torque capacity

l

Modified front and rear output and cross shaft housings

l

Intermediate gear bearing pre-load now controlled by a selective, non-collapsible spacer

l

Speedometer drive and driven gears not fitted for this application

l

Modified high/low sleeve

l

Modified front output flange and mud shield

l

Differential lock fitted to certain vehicles, but no longer driver operated

l

Fixed 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

l

Ribs added to main casing to reduce operating noise

l

Revised machining process for intermediate gears to reduce operating noise

l

Bearing retaining nut on the differential carrier has patchlock added to the threads

l

Interlock solenoid moved from main casing to selector lever assembly

l

Intermediate gears modified with machined internal shoulder and bearing circlips deleted

l

Driver operated differential lock

l

High/Low selector shaft fitted with spring assist

l

Existing differential lock switch replaced by 2 new switches of improved design with the additional switch installed
adjacent to the existing switch location.

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 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.

TRANSFER BOX - LT230SE

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DESCRIPTION AND OPERATION

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 assister 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.

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 - If fitted
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.