1995 LAND ROVER DISCOVERY torque

ZF
1
DESCRIPTION AND OPERATION DESCRIPTION
The automatic transmission is specially tailored version of the ZF4 HP22, used by many manufacturer's of high
performance vehicles.
A three element torque converter delivers the power to a four speed epicyclic transmission. First, second and third
gears are reduction ratios but fourth is an overdrive gear for high speed cruising. A direct drive clutch, integral with
the torque converter operates to engage fourth gear.
The gear selector has seven positions as follows:
P = Park provides a mechanical lock on the output shaft.
R = Reverse gear.
N = Neutral.
D = Provides a 1st gear start and automatic shifts 1-2-3-4-3-2-1.
3 = Provides a 1st gear start and automatic shifts 1-2-3-2-1.
2 = Provides a 1st gear start and automatic shifts 1-2-1 or 3-2-1.
1 = Provides a 1st gear start with no up shifts, or 3-2-1.
All automatic shifts are automatically controlled by the valve block and an hydraulic governor driven by the output
shaft.

ZF
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DESCRIPTION AND OPERATION 3rd gear D selected
Clutches 4, 5, 7 and 11 are engaged. Freewheel 15 and 16 are overrun. Epicyclic gear set 9 and 10 rotate as a
solid unit at a ratio of 1:1.
4th gear D selected
Clutches 4, 5, 7 and 12 are engaged. Freewheel 14, 15 and 16 are overrun. Epicyclic gear set 9 rotates as a solid
unit. The hollow shaft with the sun wheel of epicyclic gear set 10 is locked.
Above a predetermined road speed, clutch 2 locks the gearbox power input direct to the engine, by-passing the
torque converter.

ZF
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FAULT DIAGNOSIS 1. Torque converter housing assembly
2. Gearbox pump and casing assembly
3. Governor and adaptor housing assembly

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FAULT DIAGNOSIS SYMPTOM 10 - None or harsh engagement of
direct drive clutch
NOTE: The direct drive clutch will only
engage if 4th gear is engaged at 40 to 45
mph.
Carry out road test pressure check with gauge
connected to torque converter.
ú Normal pressure
FAULT - Failed direct drive clutch
ú Pressures correct but remains high
FAULTS POSSIBLE -
Direct drive clutch and torque converter
control valve stuck
Hysteresis valve stuck
Direct drive clutch control valve stuck
SYMPTOM 11 - Direct drive clutch shift point
incorrect or at low speed
NOTE: Direct drive clutch engagement at
low speed will cause vibration in the
torque converter
Carry out mainline and torque converter pressure
check
ú Normal pressure
FAULT - Governor valve sticking
ú Low or incorrect pressure
FAULTS POSSIBLE -
Direct drive clutch and torque converter
control valve sticking.
Hysteresis valve stuck.
Direct drive clutch control valve stuck.
SYMPTOM 12 - Drives in 'D' but immediately
upshifts to 3rd
FAULT - 2nd to 3rd shift valve stuck.
SYMPTOM 13 - With 'D' selected vehicle starts in
2nd
FAULTS POSSIBLE -
1st and 2nd shift valve stuck.
Governor sleeve sticking.
SYMPTOM 14 - With 'D' selected vehicle starts in
3rd
FAULTS POSSIBLE -
1st to 2nd and 2nd to 3rd shift valves stuck.
Governor sleeve sticking.SYMPTOM 15 - No kickdown 4th to 3rd
FAULT - 4th to 3rd kickdown valve stuck.
SYMPTOM 16 - Upshifts/downshifts and kickdown
shifts at incorrect road speeds
Check throttle kickdown cable adjustment
Carry out main line pressure check
ú Normal pressure
FAULT - Governor valve sticking
ú Incorrect pressure
FAULTS POSSIBLE -
Incorrect throttle valve adjustment
Primary regulator sticking
SYMPTOM 17 - No upshifts at light throttle
FAULTS POSSIBLE
Governor valve sticking
Shift valves sticking
SYMPTOM 18 - No engine braking '3' selected 3rd
gear
FAULT - Clutch 'C'
SYMPTOM 19 - Delayed or no downshift occurs
when making a manual selection from '3' to '2'
FAULTS POSSIBLE -
2nd and 3rd upshift valve sticking.
Governor valve sticking.
'2' Position interlock valve sticking.
SYMPTOM 20 - At speeds below 28 mph when
making a manual selection from '2' to '1',
downshift is delayed or does not occur
FAULTS POSSIBLE -
Governor sticking.
1st to 2nd shift valve sticking.
'1' Position interlock valve sticking.
SYMPTOM 21 - '1' Selected 1st gear no engine
braking
FAULT - Clutch brake 3
SYMPTOM 22 - '2' Selected 2nd gear no engine
braking
FAULT - Clutch brake 1
SYMPTOM 23 - Vehicle drives forward in 'N'
FAULT - Clutch 'A' stuck

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REPAIR LT230T TRANSFER GEARBOX WITH AUTOMATIC
GEARBOX ASSEMBLY - V8i
Service repair no - 44.20.04
Removal from V8i engine
The assembled transfer gearbox, automatic gearbox
and torque converter is removed from underneath the
vehicle. Use a transmission hoist with an adaptor
plate for securing the assembly to the hoist. The
adaptor can be manufactured locally to the drawing
below or purchased from:- Straight Set Engineering,
England. Tel.01909 480055
WARNING: When using a transmission
hoist it is essential to follow the hoist
manufacturer's instructions.

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REPAIR 19.Disconnect rear propeller shaft to output flange,
and tie to one side.
20.Repeat instructions 18 and 19 on front propeller
shaft to main gearbox.
21.Remove bolts retaining silencer front and rear
securing brackets and tie silencer to one side.
22.Disconnect oil cooler feed and return pipes from
bottom and side of main gearbox.
23.Release cooler pipes from clamp at engine sump
and remove distance piece.
24.Blank pipe ends and unions.
25.Move oil cooler pipes clear of transmission and
tie aside.
26.Disconnect selector cable from operating lever.
27.Disconnect inhibitor switch at multiplug.
28.Attach adaptor plate to hoist.
29.Remove two bolts from transfer gearbox rear
cover.
30.Raise hoist to align adaptor plate with transfer
gearbox and transmission. Secure to transfer
gearbox at rear cover with two bolts removed.
31.Adjust hoist to take weight of transmission.
32.Remove nuts and bolts securing right transfer
gearbox mounting bracket to chassis.
33.Repeat for the left mounting bracket. Removal of
these fixings will also free speedometer
transducer bracket
34.Remove right side mounting bracket to flexible
mounting rubber retaining nut.
35.Lower hoist until rear brake drum clears
passenger footwell. Check engine does not
crush any components while lowering.
36.Remove clip and clevis pin from park brake
lever.
37.Remove clip securing outer brake cable
38.The park brake cable is now free.
39.Disconnect leads from transfer gearbox
temperature sensor and differential lock warning
light switch.
40.Remove ties securing breather pipes to harness.
41.Remove bell housing access plate complete with
gasket.
42.Rotate engine, using crankshaft pulley, until two
access holes are visible in drive plate/ring gear
assembly through bell housing bottom cover
opening.
43.Identify an access hole and bolt hole to aid
reassembly.
44.Remove bolts securing drive plate to convertor
through access holes.
45.Rotate crankshaft half turn to access and
remove remaining bolts.
46.Disconnect oil dipstick tube at main gearbox.
47.Remove bolt at bell housing and detach dipstick
tube. Blank pipe end and union.
48.Position hoist jack channel under engine and
support using a wooden block.
49.Remove bell housing to engine securing bolts,
also detach harness bracket from bell housing.
50.Ease transmission rearwards to allow access to
secure torque converter in bell housing.
51.Lower hoist and complete removal of
transmission.
Refit
52.Ensure torque converter is retained in bell
housing.
53.Secure transmission to adaptor plate on lifting
hoist.
54.Raise hoist and locate transmission with engine.
55.Remove torque converter retainer.
56.Complete attachment of transmission to engine
and fit bell housing bolts. Fit the dipstick tube
bracket and harness bracket to their respective
bolts.
57.Complete refitting by reversing removal
procedure. Note the following important points.
58.Drive plate to torque converter bolts are to be
coated with Loctite 290 prior to assembly.
59.Refill transfer and main gearboxes with correct
grade oil.
See LUBRICANTS, FLUIDS AND
CAPACITIES, Information, Recommended
Lubricants and Fluids
60.Check operation of parking brake and adjust as
necessary.
See SECTION 10, Maintenance,
Vehicle Interior

44AUTOMATIC GEARBOX
4
REPAIR LT230T TRANSFER GEARBOX WITH AUTOMATIC
GEARBOX ASSEMBLY - Tdi
Service repair no - 44.20.04
Removal from Tdi engine
The assembled transfer gearbox, automatic gearbox
and torque converter is removed from underneath the
vehicle. Use a transmission hoist with an adaptor
plate for securing the assembly to the hoist.
WARNING: When using a transmission
hoist it is essential to follow the hoist
manufacturer's instructions.

44AUTOMATIC GEARBOX
6
REPAIR 13.Remove starter.
14.Working through starter aperture note position of
torque converter flexible drive plate to facilitate
refitting.
15.Remove the four torque convertor to flexible
drive securing bolts, rotating engine to gain
access to each individual bolt.
16.Raise vehicle on four post ramp [hoist].
17.Drain lubrication oil from transfer and main
gearboxes.
18.Disconnect speedometer cable from transfer
gearbox and disconnect associated clipping.
19.Remove rear propeller shaft.
See PROPELLER
SHAFTS, Overhaul, Flexible Coupling
20.Disconnect front propeller shaft at transfer
gearbox and tie to one side.
21.Remove exhaust front pipe.
22.Remove bolts securing front and centre silencer
mounting brackets and tie silencer to one side.
23.Disconnect oil cooler pipes from gearbox.
24.Blank off pipes and union connections.
25.Remove bolt securing retaining bracket to sump
and move cooler pipes aside.
26.Disconnect selector cable from lever on side of
gearbox.
27.Disconnect inhibitor switch multi-plug.
28.Disconnect park brake cable from linkage to park
brake lever.
29.Disconnect electrical connections from
differential lock switch on transfer gearbox.
30.Remove two lower bolts from transfer gearbox
input bearing support plate.
31.Assemble approved support cradle to
transmission hoist.32.Raise hoist and secure cradle to transfer
gearbox input bearing support plate using bolts
removed.
33.Disconnect gearbox mounting brackets from
chassis cross member.
34.Remove chassis cross member.
35.Lower transmission sufficiently to allow access
to items attached to top of gearbox.
36.Remove left hand gearbox mounting bracket
assembly.
37.Remove ties from breather pipes and harness.
38.Remove nut securing gearbox oil filler/dip stick
tube to bell housing.
39.Release union nut at gearbox sump and remove
filler/dipstick tube. Fit blanking plugs.
40.Support engine using a wooden block with a
suitable ramp [hoist] jack.
41.Remove nut securing kick down cable bracket to
bell housing.
42.Remove two bolts securing top of bell housing to
flywheel housing.
43.Remove nuts securing bell housing to flywheel
housing and withdraw transmission assembly
from engine.
44.Fit a suitable torque converter retaining strap to
the bell housing.
45.Remove hoist and transmission from under
vehicle.
46.Fit lifting eyes to transmission.
47.Using suitable chains and lifting tackle take
weight of transmission assembly.
48.Remove bolts securing transmission cradle to
transfer box and withdraw hoist complete with
cradle.
49.Refit bolts to cover plate.