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Model DX Roverdrive is made to be used on 90, 110 and
Defender models fitted with the Land Rover LT 230 transfer
case. It can also be used on Discovery and Range Rover
models, but you will need to make some alterations to
the coach work of the body just aft of the transfer
case in order to create sufficient space. At the present
the DX Roverdrive is only available for 4 and 5 cylinder
models as tests on V8 powered Land Rovers have not been
completed.
 Unlike
previous designs of Land Rover overdrives the "ROVERDRIVE"
unit does not have an exclusive oil reservoir. As the
vehicle is driven oil is pumped from the transfer case
into the overdrive by means of a simple Archimedes screw
on the overdrive main shaft. This incoming oil lubricates
the main thrust bearing in passing and is added to oil
in the overdrive. Surplus oil in the overdrive housing
overflows down the tubular main shaft, lubricates all
coupling components and returns to the transfer case.
This lubrication arrangement has several
advantages over previous overdrives:
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There are no dynamic seals to leak
and no requirement for an air vent.
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The overdrive casing can be made compact
as there is no requirement for a large sump to store
oil and dissipate heat. Any heat generated in the
overdrive is carried off in the circulating oil
and dissipates in the main body of the transfer
case.
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There is only one place to check and
maintain oil level - the transfer case.
The Model LT 230 transfer case has a history
of problems with input shafts fretting due to poor lubrication
between the shaft and the input gear on the transfer
case. When installing the DX Roverdrive make sure that
the input shaft at the top of the transfer case is in
good condition.
Installation of the DX Roverdrive cures
the fretting problem as the input shaft is effectively
lubricated by oil circulating from the Roverdrive.
There are several different types of input
gears used in the LT 230 transfer case. When you order
a DX Roverdrive we need to know the suffix number of
your transfer case so we can supply you with the correct
gear. When you install a DX Roverdrive you need to set
up the tension on the input gear bearings. This is accomplished
by setting up the bearing preload using shims and a
spring balance.
The lever kit supplied with the DX Roverdrive
will fit all models of Defender and Discovery, and is
constructed so that the overdrive lever is placed on
the lefthand side of the transmission tunnel where the
actuating rod does not interfere with the High/Low shaft
mechanism.
There is considerable variation in the transmission
tunnel arrangement on different models of the Land Rover.
Some adjustment of the operating lever position can
be made by altering the components supplied.
Extensive long distance testing of DX Roverdrives
in Europe, North America & Australia has shown that
fuel consumption figures approaching 30 mpg can be expected
when using the overdrive on 300 tdi and td 5 Landrovers.
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