Land Rover Borg Warner 44 62 Transfer Box Overhaul Rover Manual

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DESCRIPTION AND OPERATION7
The selector fork is mounted on a second shaft
located within the front and rear casings but is able
to slide in the casing mountings. A cam follower on
the selector fork engages with the cam track of the
interlock spool. When the ratio control motor rotates
the interlock spool, the cam follower of the selector
fork follows the cam track of the interlock spool. This
converts rotational movement of the interlock spool
into linear movement of the selector fork.
The selector fork is engaged to the reduction hub.
Linear movement of the selector fork is transmitted
to the reduction hub, moving it between High, Low
and neutral positions. In the event of the reduction
hub gear failing to mesh with the epicyclic gear set,
wind-up of the interlock is prevented by the interlock
spool springs. The springs apply a constant torque
to the cam track casting until the reduction hub
engages with the epicyclic gear.
Ratio control motor
The ratio control motor drives the selector
mechanism and is controlled by the transfer box
electronic control unit (ECU). The ECU monitors a
number of variables including the position of the
ratio control motor, the speed of the vehicle, and the
drive ratio selected by the driver. When a ratio
change is requested, the transfer box ECU checks
that conditions are favourable for the change, for
example that the vehicle speed is sufficiently low to
permit engagement. The ECU then drives the ratio
control motor to the required position. When the
conditions for a ratio change are unfavourable, the
transfer box ECU communicates instructions to the
driver through the Message Centre and will not
attempt to change ratios until the correct conditions
are met.
INPUTS OUTPUTS
Ratio control motor position Ratio control motor drive
Range selector switchECUMessage Centre
Vehicle road speed H-gate (automatic gearbox)
Gear lever neutral 
						

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8
DESCRIPTION AND OPERATION Differential unit
The differential unit is driven from the intermediate
shaft through a Morse chain. The outer casing of the
differential unit is the differential input, while the sun
gear provides the front output and the planet carrier
the rear output.The planet carrier contains three sets of gears,
which mesh in pairs to maintain the correct
directional relationship between front and rear
differential outputs. The rear output shaft passes
through the differential unit, engaging with the planet
carrier and protruding through the sun gear shaft to
locate to the VCU inner spline. The sun gear shaft
locates to the VCU outer spline. 
						

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DESCRIPTION AND OPERATION9
Viscous coupling (VCU)
The VCU comprises a short cylinder which contains
an inner shaft with slotted discs attached to its outer
surface, and a similar set of discs attached to the
inner surface of the cylinder. Both sets of discs are
arranged so that they interleave alternately and in
close proximity to each other. The VCU is sealed,
and filled with a type of silicone jelly which has the
property of increasing its viscosity with rises in
temperature and shear forces.
Variations in speed between the front and rear
output shafts are transmitted through the VCU, with
the speed differential occurring between the inner
shaft and the cylinder. In normal road conditions
where the speed variation between front and rear
shafts is low, the difference in rotational speed
between the VCU discs is also low. As a result, the
shear forces acting on the silicon jelly are marginal
and offer little resistance to the different rotational
speeds of the output shafts.In cases where large rotational speed differences
occur between the front and rear output shafts, such
as in rough terrain conditions, the speed variation
between the discs is high with a subsequent
increase in the shear forces acting on the viscous
jelly. The resulting increase in viscosity generates
sufficient shear resistance to force both sets of discs
to rotate at similar speeds, reducing axle slippage
and loss of traction. 
						

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10
DESCRIPTION AND OPERATION Lubrication
Internal lubrication of the transfer gearbox is
provided by a low pressure, plunger-type oil pump
mounted on the rear of the intermediate shaft. Oil
pick-up is through a strainer in the transfer box
sump. From the pump, oil is supplied through the
intermediate shaft to the epicyclic gear set. The
differential and Morse chain are partially immersed
in oil and lubricated as the components rotate. The
VCU is a fully sealed unit and does not require
separate lubrication. 
						

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OVERHAUL1
RATIO CONTROL MOTOR
Service repair no - 41.30.03/01
Remove
1.Remove 4 bolts securing motor to transfer box.
2.Remove motor.
Refit
1.Fit motor and engage to drive spindle.
2.Tighten bolts to 10 Nm. (7 lbf.ft).INPUT SHAFT OIL SEAL
Service repair no - 41.20.50/01
Remove
1.Using a flat bladed screwdriver free of rough
edges, ease input shaft oil seal from transfer
box front casing.
CAUTION: Do not mark sealing surface of
front casing.
Refit
1.Clean sealing surface of front casing and
running surface of input shaft. Ensure all traces
of rubber are removed.
CAUTION: Do not use a metal scraper as
this may damage sealing surfaces.
2.Lubricate oil seal sealing face with clean
gearbox oil.
3.Position oil seal to transfer box front casing
and fit oil seal using LRT-41-011. 
						

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2
OVERHAUL FRONT OUTPUT SHAFT DRIVE FLANGE
Service repair no - 41.20.15/01
Remove
1.Using LRT-51-003 to restrain front output shaft
drive flange, remove and discard nut securing
drive flange to front output shaft.
2.Collect washer and seal.
3.Using LRT-99-500 if necessary, remove drive
flange from front output shaft.Refit
1.Clean running surface of drive flange. Ensure
all traces of rubber are removed.
CAUTION: Do not use a metal scraper as
this may damage sealing surface.
2.Fit drive flange to front output shaft.
3.Fit seal, washer and new nut to front output
shaft.
4.Using LRT-51-003 to restrain drive flange,
tighten nut to 220 Nm. (162 lbf.ft) 
						

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OVERHAUL3
FRONT OUTPUT SHAFT OIL SEAL
Service repair no - 41.20.51/01
Remove
1.Remove front output shaft drive flange.
See
this section.
2.Using a flat bladed screwdriver free of rough
edges, ease front output shaft oil seal from
front casing.
CAUTION: Do not mark sealing surface of
front casing.
3.Remove oil seal.Refit
1.Clean sealing area of front casing and running
surface of front drive flange. Ensure all traces
of rubber are removed.
CAUTION: Do not use a metal scraper as
this may damage sealing surfaces.
2.Lubricate sealing faces of new seal with clean
gearbox oil.
3.Using LRT-41-013 fit front output shaft oil seal
to front casing. Ensure that seal is square to
casing bore.
4.Fit front output shaft drive flange.
See this
section. 
						

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4
OVERHAUL VISCOUS COUPLING UNIT (VCU)
Service repair no - 41.20.66/01
Remove
1.Remove front output shaft drive flange.
See
this section.
2.Remove 6 bolts securing VCU housing to
transfer box.
3.With care, break front face RTV seal and
remove VCU assembly.
Do not carry out further dismantling if
component is removed for access only.
4.Press out viscous coupling from housing.
CAUTION: Protect output shaft thread and
do not use excessive force when pressing
out viscous coupling.
Refit
1.Clean mating surfaces of viscous coupling
housing and transfer box.
CAUTION: Do not use a metal scraper as
this may damage sealing surfaces.
2.Clean bearing and VCU mating faces.
3.Press VCU into bearing.
4.Apply a continuous 2mm bead of sealant to
VCU housing mating face. Path to be around
inside of bolt holes.
5.Fit VCU assembly to transfer box ensuring
correct alignment of bolt holes before
disturbing RTV bead.
6.Fit bolts and progressively tighten to 35 Nm.
(26 lbf.ft)
7.Fit front output shaft drive flange.
See this
section.
EPICYCLIC GEAR SET
Service repair no - 41.20.68/01
Remove
1.Remove viscous coupling assembly.
See this
section.
2.Remove 17 bolts securing halves of transfer
box casing.
3.Carefully break RTV seal and remove front
transfer gearbox casing from rear casing.
4.Position front casing, input shaft upwards.
Position block of wood under epicyclic gear
set. 
						

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OVERHAUL5
5.Using a flat bladed screwdriver free of rough
edges, ease input shaft oil seal from front
casing.
CAUTION: Do not mark sealing surface of
front casing.
6.Release circlip retaining epicyclic gear to front
casing. Epicyclic gear set will fall onto block of
wood.
7.Remove epicyclic gear set.Refit
1.Clean RTV sealant from front and rear casing
mating surfaces.
CAUTION: Do not use a metal scraper as
this may damage sealing surfaces.
2.Clean bearing and input shaft mating faces.
3.Clean sealing area of front casing and running
surface of input shaft. Ensure all traces of
rubber are removed from sealing surfaces.
CAUTION: Do not use a metal scraper as
this may damage sealing surfaces.
4.Fit epicyclic gear set to front casing.
5.Fit circlip retaining epicyclic gear set to front
casing.
6.Lubricate sealing faces of seal with clean
gearbox oil.
7.Using LRT-41-011 drift input shaft seal into
front casing.
8.If removed, fit 2 dowels to front casing.
9.Apply a continuous 2 mm bead of RTV sealant
to rear casing mating face. Path to be around
inside of bolt holes.
10.Fit front casing to rear casing, ensure bolt
holes are aligned before disturbing RTV
sealant.
11.Fit bolts securing front casing to rear casing
and progressively tighten to 35 Nm. (26 lbf.ft)
12.Check freedom of rotation of input shaft and
that rear output shaft rotates.
13.Fit viscous coupling assembly.
See this
section. 
						

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6
OVERHAUL INPUT SHAFT BEARING
Service repair no - 41.20.65/01
Remove
1.Remove epicyclic gear set.
See this section.
2.Remove snap ring retaining input shaft bearing
to front casing.
3.Press out input shaft bearing.
Refit
1.Clean bearing and front casing mating faces,
ensure casing is free from burrs.
2.Press bearing into front casing.
3.Fit snap ring retaining bearing to front casing.
4.Fit epicyclic gear set.
See this section.
FRONT OUTPUT SHAFT BEARING
Service repair no - 41.20.08/01
Remove
1.Remove viscous coupling unit (VCU).
See this
section.
2.Using a flat bladed screwdriver free of rough
edges, ease oil seal from VCU housing.
CAUTION: Do not mark sealing surfaces of
VCU housing.
3.Remove circlip retaining output shaft bearing to
casing.
4.Press out bearing from VCU casing.