clutch LAND ROVER DISCOVERY 2002 Workshop Manual

TRANSFER BOX - LT230SE
OVERHAUL 41-55
37.Heat the front output housing to 100°C (210°F)
and fit new output shaft bearing using tool
LRT-41-011.
38.Allow housing to air cool.
39.Fit new bearing retaining circlip ensuring that
circlip is fully seated.
40.Using tool LRT-41-012, fit new output shaft oil
seal. Check that oil seal is just contacting
circlip. 41.Position selected shim in front output housing
and using tool LRT-54-003, fit new differential
front bearing track.
42.Fit bearing spacer to output shaft with chamfer
on spacer towards threaded end.
43. If fitted: Fit dog clutch with flange on clutch
facing towards splined end.
44.Using a copper mallet, drive output shaft into
bearing.
Note: Carry out the following operations for
transfer boxes fitted with differential lock.
45.Compress differential lock selector spring and
fit selector fork.
46.Position selector fork to groove in dog clutch.
47.Fit selector shaft and locate in housing recess,
rotate shaft until the two flats for retaining clips
are at right angles to the cover plate mating
face.

TRANSFER BOX - LT230SE
41-56 OVERHAUL
48.Compress selector spring and fit retaining clips
at each end of spring.
CAUTION: Ensure ends of spring are fully
seated in recess of clips.
49.Fit detent ball and spring.
50.Apply Loctite 290 to threads of detent plug.
51.Fit and tighten detent plug, then loosen 2
complete turns.
52.Fit new 'O' ring to differential lock selector
housing.
53.Fit selector housing, ensure selector finger is
located in shaft recess.
54.Apply Loctite 290 to threads of bolts, and
tighten selector housing bolts to 25 Nm (18
lbf.ft).
55.Clean threads of differential lock warning lamp
switch(es).
56.Up to 03 MY: Fit nut to switch head with
counterbore positioned towards switch head.
The nut acts as a spacer to ensure that
switch setting is correct. Always ensure
that nut is fully tightened to switch head (no
gap).
57.Apply Hylomar PL 32 sealant to threads of
differential warning lamp switch(es).
58.Up to 03 MY: Position switch into front output
housing until nut bottoms out on housing;
tighten nut to 11 Nm (8 lbf.ft)
59.03 MY onwards: Fit new sealing washers to
switches, fit switches in front output housing
and tighten to 25Nm (18 lbf.ft).
Note: Carry out the following operations for all
transfer boxes.
60.Apply sealant, Part No. STC 3254 to front
output shaft housing. 61.Position housing ensuring that output shaft and
dog clutch splines - if fitted are correctly
engaged.
62.Clean output housing bolt threads.
63.Apply Loctite 290 to threads of bolts.
64.Fit output shaft housing bolts and tighten in a
diagonal sequence to 45 Nm (33 lbf.ft).
65.Fit output flange, new felt washer, steel washer
and new retaining nut.
66.Using tool LRT-51-003 to restrain flange,
tighten output flange nut to 162 Nm (119 lbf.ft).
67. If fitted - Operate differential lock selector
lever and check that detent ball can be felt to
positively engage/disengage with grooves in
shaft. Screw plug in or out until setting is
correct.
68.Fit high/low selector shaft detent ball and
spring.
69.Apply Loctite 290 sealant to threads of high/low
selector shaft detent plug.
70.Fit and tighten plug, then loosen 2 complete
turns.
71. Operate high/low selector lever and check that
detent ball can be felt to positively engage/
disengage with grooves in shaft. Screw plug in
or out until setting is correct.
72.Fit intermediate gear cluster.

+ TRANSFER BOX - LT230SE,
OVERHAUL, Intermediate gear assembly.

TRANSFER BOX - LT230SE
OVERHAUL 41-57
Dog clutch - differential lock
$% 41.20.23
Disassembly
1.Remove 6 bolts securing high/low cross shaft
housing to front output shaft housing and
remove housing.
2.Note position of longest bolt and remove 8
bolts securing front output shaft housing to
main casing and remove housing.
3.Remove 3 bolts securing differential lock
selector housing and remove housing. 4.Remove and discard 'O' ring from selector
housing.
5.Remove differential warning lamp switch and
locknut.
Note: Locknut is only fitted to switches up to 03
MY, a modified switch and sealing washer is
fitted from 03 MY onwards..
6.03 MY onwards: Remove differential lock
warning lamp switch from end of front output
shaft housing, discard sealing washer.
7.Remove Allen plug and remove detent spring
and ball.
8.Compress differential lock selector fork spring
and remove retaining clips from each end of
spring.
9.Withdraw differential lock selector shaft from
front output housing, recover spring and
remove selector fork.

TRANSFER BOX - LT230SE
41-58 OVERHAUL
10.Position tool LRT-51-003 to output shaft drive
flange, remove and discard nut.
11.Remove and discard steel and felt washers.
Remove output shaft drive flange.
12.Using a copper mallet, drive output shaft from
housing.
13.Noting its fitted position, remove bearing
spacer from output shaft.
14.Noting its fitted position, remove dog clutch
from output shaft.
15.Remove and discard oil seal from housing. Reassembly
1.Clean differential lock components.
2.Lubricate components with gearbox oil.
3.Using tool LRT-41-012, fit new output shaft oil
seal.
4.Fit bearing spacer to output shaft with chamfer
on spacer towards threaded end.
5.Fit dog clutch with flange on clutch facing
towards splined end.
6.Using a copper mallet, drive output shaft into
bearing.
7.Compress differential lock selector spring and
fit selector fork.
8.Position selector fork to groove in dog clutch.
9.Fit selector shaft and locate in housing recess,
rotate shaft until the two flats for retaining clips
are at right angles to the cover plate mating
face.
10.Compress selector spring and fit retaining clips
at each end of spring.
CAUTION: Ensure ends of spring are fully
seated in recess in clips.
11.Fit detent ball and spring.
12.Apply Loctite 290 to threads of detent plug.
13.Fit and tighten detent plug, then unscrew 2
complete turns.
14.Fit new 'O' ring to differential lock selector
housing.
15.Fit selector housing, ensure selector finger is
located in shaft recess.
16.Apply Loctite 290 to threads of bolts and tighten
selector housing bolts to 25 Nm (18 lbf.ft).
17.Apply sealant, Part No. STC 3254 to front
output shaft housing.
18.Position housing ensuring that output shaft and
dog clutch splines are correctly engaged.
19.Apply Loctite 290 to threads of bolts.
20.Fit front output shaft housing bolts and tighten
in a diagonal sequence to 45 Nm (33 lbf.ft).

TRANSFER BOX - LT230SE
41-62 OVERHAUL
7.Position dial gauge with stylus contacting input
gear, push input gear rearwards and zero
gauge.
8.Push input gear forwards and note gauge
reading.
9.Calculate thickness of shim required using the
formula - A+B+C=D where:
lA= Thickness of installed shim - 3.15 mm
(0.12 in)
lB= Recorded end-float.
lC= Required pre-load - 0.05 mm (0.002 in).
lD= Thickness of shim required.
10.If an alternative shim is required to establish
correct pre-load, fit an alternative shim. Shims
are available from 3.15 to 4.00 mm (0.12 to
0.16 in) thickness, in increments of 0.05 mm
(0.002 in).
11.Remove 2 bolts, remove bearing housing and
input gear.
12.Lubricate input gear and bearings with
recommended oil.
13.Position input gear into main casing.
14.Apply sealant, Part No. STC 3254 to bearing
housing and cover.
15.Position bearing housing/cover, align reference
marks and tighten by diagonal selection to 45
Nm (33 lbf.ft).
16.Using tool LRT-37-014 fit new input shaft oil
seal.
Low gear - differential
$% 41.20.62
Disassembly
1.Remove differential.

+ TRANSFER BOX - LT230SE,
OVERHAUL, Dog clutch - differential lock.
2.Secure differential in a soft jawed vice.
3.Release staking from bearing retaining nut.
4.Using tool LRT-41-007 remove and discard
bearing retaining nut.
5.Position tool LRT-99-002. to a vice.
6.Position tool LRT-41-001 around rear
differential bearing, position differential to tool
LRT-99-002 and press off bearing.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-7
The gearbox consists of a torque converter housing, an intermediate plate, a gearbox housing and a rear extension
housing, bolted together in series. The rear of the gearbox is supported by a rubber mounting installed between a
mounting bracket on the gearbox and the LH chassis rail. A heat shield is installed on the mounting to protect it from
the exhaust.
Sectioned view of gearbox
1Lock-up clutch
2Impeller
3Turbine
4Forward drive clutch
5Reverse drive clutch
6Brake clutch
7Brake clutch
8Brake clutch
9Epicyclic gear set10Epicyclic gear set
11Clutch
12Brake clutch
13Output shaft
14Freewheel (one way clutch)
15Freewheel (one way clutch)
16Freewheel (one way clutch)
17Stator and one way clutch
Torque converter housing
The torque converter housing attaches the gearbox to the engine and contains the torque converter. Different torque
converter housings are used to accommodate the difference between the V8 and Td5 engine interfaces. The torque
converter is connected to the engine drive plate and transmits the drive from the engine to the gearbox input shaft.
When engaged, a hydraulic lock-up clutch in the torque converter prevents slippage, to give a direct drive from the
engine to the gearbox for improved driving response.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-8 DESCRIPTION AND OPERATION
Intermediate plate
The intermediate plate supports the gearbox input shaft and provides the interface between the transmission fluid
pump and the lubrication circuit. The pump attaches to the front of the intermediate plate and is driven by the impeller
in the torque converter. The pump pressurises transmission fluid drawn from the sump on the gearbox housing. The
pressurised fluid then circulates through the torque converter and gearbox housing components for cooling,
lubrication and gear shift purposes. Ports around the outer periphery of the intermediate plate provide the inlet and
outlet connections to the fluid cooler and a pressure take-off point for servicing.
Gearbox housing
The gearbox housing contains two epicyclic gear sets on input and output shafts. Hydraulic brake clutches on the
shafts, control which elements of the gear sets are engaged, and their direction of rotation, to produce the P and N
selections, four forward gear ratios and one reverse gear ratio.
Gear ratios
Gear Ratio
1st 2.480 : 1
2nd 1.480 : 1
3rd 1.000 : 1
4th 0.728 : 1
Reverse 2.086 : 1

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-10 DESCRIPTION AND OPERATION
The lock-up and brake clutches are operated by pressurised transmission fluid from the valve block in the sump. A
manual valve and four solenoid valves, also known as Motorised Valves (MV), control the supply of pressurised
transmission fluid from the valve block:
lThe manual valve controls the supply in P, R, N and D.
lSolenoid valves MV 1 and MV 2 control the supplies that operate the brake clutches for shift control.
lSolenoid valve MV 3 controls the supply that operates the lock-up clutch.
lSolenoid valve MV 4 modulates the pressure of the supplies to the brake clutches, to control shift quality.
Operation of the manual valve is controlled by the selector lever assembly. In the gearbox, a selector shaft engages
with the manual valve. The selector shaft is connected to the selector lever assembly via the selector cable and a
selector lever on the left side of the gearbox. The selector shaft also operates a mechanism that locks the output shaft
when P is selected.
Operation of the solenoid valves is controlled by the EAT ECU.
An output shaft speed sensor in the gearbox housing outputs a signal to the EAT ECU. The EAT ECU compares
output shaft speed with engine speed to determine the engaged gear, and output shaft speed with vehicle speed to
confirm the range selected on the transfer box.
A bayonet lock electrical connector in the gearbox casing, to the rear of the selector lever, connects the solenoid
valves and the output shaft speed sensor to the vehicle wiring.
A pressed steel sump encloses the valve block and collects transmission fluid draining from the gearbox housing. A
suction pipe and filter on the underside of the valve block connect to the inlet side of the fluid pump. A magnet is
installed in the sump to collect any magnetic particles that may be present. A level plug and a drain plug are installed
in the sump for servicing.
Rear extension housing
The rear extension housing provides the interface between the gearbox housing and the transfer box. A splined
extension shaft, secured to the gearbox output shaft by a bolt, transmits the drive from the gearbox to the transfer
box. A seal in the rear of the housing prevents leakage past the extension shaft. A breather pipe, attached to the left
side of the rear extension housing, ventilates the interior of the gearbox and rear extension housings to atmosphere.
The open end of the breather pipe is located in the engine compartment at the right front corner of the engine sump
on gearboxes fitted to early vehicles and is clipped to the top of the gearbox on later vehicles.
Gearbox power flows
The following Figures show the power flow through the gearbox for each forward gear when D is selected, and for
reverse. The key to the Item numbers on the Figures, and in parenthesis in the accompanying text, can be found on
the 'Sectioned view of gearbox' Figure, above.
1st Gear (D selected)
Clutches (4) and (11) are engaged. The front planet gear carrier of gear set (9) locks against the gearbox housing
through freewheel (15) when the engine powers the vehicle, and freewheels when the vehicle is coasting. Gear set
(10) rotates as a solid unit with the front planet gear carrier. In 1st gear hold brake clutch (8) is applied to provide
overrun braking.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-11
2nd Gear (D selected)
Clutches (4), (6), (7) and (11) are engaged. Freewheel (15) overruns. The hollow shaft with the sun wheel of gear set
(9) is locked. Gear set (10) also rotates as a solid unit.
3rd Gear (D selected)
Clutches (4), (5), (7) and (11) are engaged. Freewheels (15) and (16) are overrun. Gear sets (9) and (10) rotate as a
solid unit.
4th Gear (D selected)
Clutches (4), (5), (7) and (12) are engaged. Freewheels (14), (15) and (16) are overrun. Gear set (9) rotates as a solid
unit. The hollow shaft with the sun wheel of gear set (10) is locked.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-12 DESCRIPTION AND OPERATION
Reverse gear
Clutches (5), (8) and (11) are engaged. The front planet gear carrier of gear set (9) is locked. Gear set (10) also rotates
as a solid block.
Gear position switch
The gear position switch outputs signals that are related to the position of the selector lever assembly. The switch is
installed on the selector shaft on the left side of the gearbox. Slotted mounting holes allow the switch to be turned
relative to the shaft for adjustment. A fly lead connects the switch to the vehicle wiring.
Movement of the selector lever assembly turns the selector shaft, which operates six pairs of contacts in the switch.
The pairs of contacts are identified as the W, X, Y, Z, Park/Neutral and Reverse contacts. When closed:
lThe W, X, Y and Z contacts output a 12V ignition supply from the BCU.
lThe Park/Neutral contacts output an earth.
lThe Reverse contacts output a 12V ignition supply from the passenger compartment fuse box.
The outputs of the W, X, Y and Z contacts are monitored by the EAT ECU and the BCU to determine the position of
the selector lever assembly.
Gear position switch W, X, Y, Z outputs
The Park/Neutral contacts output to the BCU and, on diesel models, the ECM. The Reverse contacts output to the
BCU, the reversing lamps, the SLABS ECU and, where fitted, the ACE ECU and the electrochromic interior mirror.
Switch
contactsOutput
PRND 3 2 1
W12V - 12V 12V - - -
X- 12V 12V - 12V - -
Y- - 12V 12V 12V - 12V
Z- - - 12V 12V 12V -