Discovery 2. Manual - part 552

 

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Discovery 2. Manual - part 552

 

 

TRANSFER BOX - LT230SE

DESCRIPTION AND OPERATION

41-11

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

abutment bracket

Selector cable abutment bracket
Multiplug bracket
Hollow plug
High/low cross shaft housing
'O' ring
High/low cross shaft and lever
Front output shaft - Differential lock - If fitted

10 Dog clutch - Differential lock - If fitted
11 Warning lamp switch - Differential lock - If fitted 
12 Detent plug - Differential lock - If fitted
13 Detent spring - Differential lock - If fitted
14 Selector shaft - Differential lock - If fitted
15 Detent ball - Differential lock - If fitted
16 Threaded spacer - Differential lock - If fitted
17 Front output housing
18 Spring and clips - Differential lock - If fitted
19 Bolt - cover plate
20 Cover plate
21 Selector fork - Differential lock - If fitted
22 Bolt - front output housing

23 Aluminium washer
24 Warning lamp switch - Differential lock - If fitted
25 Circlip
26 Front output flange
27 Steel washer
28 Self-locking nut
29 Felt washer
30 Oil seal
31 Output shaft bearing
32 Bearing spacer
33 High/low detect switch
34 Selector finger and shaft - Differential lock - If 

fitted

35 'O' rings - Differential lock - If fitted
36 Bolt - selector housing - Differential lock - If 

fitted

37 Selector housing - Differential lock - If fitted 
38 High/low selector finger
39 Front output shaft - Vehicles not fitted with 

differential lock

40 Washer
41 Nut

TRANSFER BOX - LT230SE

41-12

DESCRIPTION AND OPERATION

Rear output housing components

Rear output shaft
Rear output housing
Bolt - rear output housing
Spacer
Output shaft bearing
Circlip
Oil seal
Mud shield
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

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

The following items are introduced later in the 03 model year build programme and therefore may not appear on all 
03 model year vehicles

l

Driver operated differential lock (if fitted)

l

High/Low selector shaft fitted with spring assist

l

Existing differential lock switch replaced by new design switch.

l

New 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.

 

 

 

 

 

 

 

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