Land Rover Defender V8i Workshop Supplement Rover Manual

							AUTOMATIC GEARBOX
1
DESCRIPTION AND OPERATION DESCRIPTION
The automatic transmission is a specially tailored version of the ZF 4HP22, used by many manufacturers 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. 
						

							44AUTOMATIC GEARBOX
2
DESCRIPTION AND OPERATION Power flow
1st gear D selected
With D selected 1st gear engaged, clutches 4 and 11 are operative. The front planet gear carrier of gear set 9 is
locked against the housing through freewheel 15 when the engine is pulling but freewheels when the vehicle is
coasting. Epicyclic gear set 10 rotates as a solid unit with the front planet gear carrier. In selector position 1 with
1st gear engaged, clutch 8 operates to prevent the loss of drive on the overrun through freewheel 15, to provide
engine braking.
2nd gear D selected
Clutches 4, 6, 7 and 11 are engaged. Freewheel 15 overruns, the hollow shaft with the sun wheel of epicyclic gear
set 9 is locked. Epicyclic gear set 10 also rotates as a solid unit. 
						

							AUTOMATIC GEARBOX
3
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. 
						

							44AUTOMATIC GEARBOX
4
DESCRIPTION AND OPERATION Reverse gear
Clutches 5, 8 and 11 are engaged. Since the front planet gear carrier of epicyclic gear set 9 is locked, the direction
of output-shaft rotation is reversed. Epicyclic gear set 10 also rotates as a solid block. 
						

							AUTOMATIC GEARBOX
1
FAULT DIAGNOSIS ZF AUTOMATIC GEARBOX
Before referring to fault symptoms, carry out initial
static checks first:
INITIAL STATIC CHECKS
Check start positions P & N only........................................................
Reverse lights R only..................................................................
Gear engagements N-D,N-3,N-2,N-1,N-R..........................................................
Full throttle Engine switched off, check full travel at engine and at.......................................................................
pedal.
Oil level N selected, engine running at normal running............................................................................
temperature.
Pressure test
2000 rev/min 10±0.3 bar .................................................................... 150±5 lbf/in
2
Idle pressure at 665 to 735 rev/min. 6.9±0.3 bar ................................. 100±5 lbf/in2
To fit pressure gauge
Service tools:
See Service tools, Automatic
Gearbox
Pressure gauge 0 to 20 bar (0 to 300 lbf/in2).
Flexible hose adaptor.
1.Site vehicle on a ramp.
2.From under gearbox, remove socket head plug
(located 10cm, 4 in from oil pipe). Fit hose
adaptorLRT-44-009.
3.Fit hose to adaptor.
4.Fit gaugeLRT-44-007to hose and route into
vehicle, ensuring hose is clear of rotating parts
and exhaust pipes.
5.Carry out road test.
See Road Test Procedure
6.Remove pressure gauge 
						

							44AUTOMATIC GEARBOX
2
FAULT DIAGNOSIS ROAD TEST PROCEDURE
Follow the procedure given commencing each test,
from a standing start, on a level road, in good weather
conditions.
ROAD TEST 1 = CHECKS 1-2-3-4-5-6-7-8
D SELECTED KICKDOWN START FROM REST
CHECK 1
Check for clutch squeal and slip. Check pressure is
10.3 bar (150 lbf/in
2).
CHECK 2
Check 1st to 2nd upshift speed and quality. Pressure
should fall to 8.3 bar (120 lbf/in
2).
CHECK 3
Check 2nd to 3rd upshift speed and quality. Pressure
should fall to 6.9 bar (100 lbf/in
2).
CHECK 4
Release throttle to allow simultaneous engagement
4th + DDC. Check shift quality and engine rpm drop of
approximately 500 rev/min.
CHECK 5
To proceed to Check 5, release throttle and check
drop out speed of direct drive clutch to 4th.
CHECK 6
Check down shift speed and quality 4th to 3rd.
NOTE: This shift is usually very smooth
and difficult to detect.
CHECK 7
Check downshift speed and quality 3rd to 2nd.
CHECK 8
Check downshift speed and quality 2nd to 1st. Also
difficult to detect.ROAD TEST 2 = CHECKS 9-10-11
D SELECTED FROM REST
FULL THROTTLE START
CHECK 9
Check 1st to 2nd upshift speed and quality.
CHECK 10
Check 2nd to 3rd upshift speed and quality.
CHECK 11
Check 3rd, 4th and direct drive clutch upshift speed
and quality.
NOTE: 4th and the direct drive clutch
engage simultaneously. 
						

							AUTOMATIC GEARBOX
3
FAULT DIAGNOSIS ROAD TEST 3 = CHECKS
12-13-14-15-16-17-18-19-20-21-22-23
D SELECTED FROM REST
LIGHT THROTTLE START
CHECK 12
Check 1st to 2nd upshift speed and quality.
CHECK 13
Check 2nd to 3rd upshift speed and quality.
CHECK 14
Check 3rd to 4th upshift speed and quality.
NOTE: This shift is usually very difficult to
detect but can be confirmed by a 200
rev/min drop in engine speed.
CHECK 15
Check speed and quality of shift into direct drive
clutch, confirmed by 300 rev/min drop in engine
speed.
NOTE: An intermediate throttle position
engagement of 4th and the direct drive
clutch, which is indicated by a fall of 500
rev/min in engine speed.
CHECK 16
At approximately 55 mph (88 kph), depress throttle to
kickdown - gearbox should change down to 2nd -
release throttle to re-engage 4th direct drive clutch
continue to accelerate gently.
CHECK 17
At approximately 80 mph (128 kph), depress throttle
to kickdown - gearbox should change down to 3rd -
release throttle to re-engage 4th direct drive clutch
and continue to accelerate gently.CHECK 18
At approximately 85 mph (138 kph), select 3rd,
gearbox should change immediately down to 3rd.
Release throttle.
CHECK 19
De-accelerate to approximately 30 mph (47 kph),
depress throttle to kickdown - geabox should
downshift to 1st gear, continue accelerating at full
throttle until 3rd gear is attained. To do this you will
have repeated check 2 of Test 1.
CHECK 20
At 80 mph (128 kph), select 2nd no downshift should
occur. Release throttle.
CHECK 21
At 65 mph (104 kph), an automatic downshift into 2nd
gear should occur. Continue to de-accelerate.
CHECK 22
At 55 mph (88 kph), select 1st. No downshift should
occur. Continue to de-accelerate.
CHECK 23
With 1 selected 2nd gear engaged, continue to
de-accelerate and at 28 mph (45 kph), the box should
automatically downshift to 1st gear after which no
upshifts will occur in this selector position.
END OF ROADTEST 
						

							44AUTOMATIC GEARBOX
4
FAULT DIAGNOSIS AUTOMATIC GEARBOX ASSEMBLY
1. Gearbox assembly
2. Inhibitor switch assembly
3. Control unit assembly
4. Filter and sump assembly 
						

							AUTOMATIC GEARBOX
5
FAULT DIAGNOSIS 1. Torque converter housing assembly
2. Gearbox pump and casing assembly
3. Governor and adaptor housing assembly