| To
make these instructions clear some photographs have
been taken using a transmission that is not mounted
a Land Rover.
1.
TOOLS REQUIRED You will need
a set of standard mechanics tools to complete this installation.
In addition to the mechanics tools you will need the
following:
- A spring loaded scale of the type fishermen use
that reads to 10Kg.
- One metre of nylon line. The type used on garden
‘weed eaters’ is ideal.
- A 50mm (2 inch) hole saw driven by an electric
drill.
- Three liters of 75-90 hydraulic gear oil.
- A small amount of axle grease.
- A small shop press will make setting up the bearing
pre-load easier but is not essential.
 2.
Drain the old oil from the transfer case. The uppermost
gear in the 230 transfer case has to be removed when
the overdrive is installed. The gear is extracted by
removing the round cover on the back of the transfer
case (Loosen six nuts and two countersunk screws to
take off). Once the cover is removed the gear can be
extracted. (On some models the gear must be rotated
to a favorable position before it will pull out). The
cover, gear and screws will not be required once the
Roverdrive is installed but store them in a safe place
in case they are ever needed. Take the opportunity to
inspect the splined input shaft for wear. These shafts
tend to run dry and yours may need replacement! Clean
off all traces of sealant from mating surfaces. If there
are any signs of leaks in the bottom of the transfer
case or brake drum this as an excellent time to make
repairs.
 3.
There is ample space to install a DX
Roverdrive in all models of Defender. To install a DX
Roverdrive in a Discovery, however, it is necessary
to increase the clearance between the transfer case
and the bodywork in the area immediately aft of the
round cover on the transfer case. This involves cutting
away some metal and doing some minor welding to seal
cavities in the bodywork. This work does not effect
the interior of the vehicle. This work is best done
by a professional welder when the car is raised on a
hoist. A similar installation in a Range Rover could
also be made.
 A
view from below of a ROVERDRIVE installed in a 1995
Discovery showing how the ledge behind the transfer
case has been cut back. This is a test vehicle and the
area cut away in this example is in excess of what is
normally required as several different versions of the
linkage were evaluated.
 4.
Remove the upper gear from the transfer
case. Hold the gear in a vice and without damaging the
roller assembly, drive the cone bearing off the forward
end of the removed gear. This bearing should be examined
for wear and replaced if deemed unserviceable.
 5.
Remove the nuts holding the two halves
of the Roverdrive together and separate the front from
the back. Place the rear of the overdrive aside.
Hold the front section of the overdrive
in a vice keeping the shaft horizontal. Use suitable
soft shims to prevent damage to the Roverdrive housing.
 6.
Assemble parts onto the shaft as shown.
First fit the gasket with no sealant. (The plain spacer
shown is not always supplied). The cone bearing (removed
in Step 4) is tapped onto the end of the shaft about
12mm or ½ an inch.
 7.
Slide the assembly into the transfer
case with the label uppermost. Now secure the assembly
to the transfer case using the three short 10mm bolts
provided in three of the six holes 120 degrees apart.
The action of securing the bolts will force the bearing
along the shaft. Now undo the three bolts and remove
the assembly.
 8.
With the front cover, once again secured
in the vice, select a stack of shims from those provided
that is a snug fit in the gap remaining between the
splined spacer and the gear. Now tap off the bearing
and place the selected shims on the shaft between the
splined spacer and the gear. Replace the bearing pushing
it all the way home.
Mount the assembly once again into the transfer case.
Secure the three short 10mm bolts as before. Make sure
that the transfer case and gearbox are both in neutral.
You should be able to rotate the annulus gear on the
overdrive freely using one hand.
 9.
Tie the nylon cord through one of the
edge holes in the annulus gear. Wrap the cord several
times around the periphery of the annulus gear and lead
it off to the hook on the spring balance. When the balance
is pulled the annulus gear should rotate when the spring
balance reads between 4 and 6 kilograms. If the tension
is not within this range shims must be added or subtracted
until this tension is achieved. This setting is important
as the correct pre-load must be applied to the shaft
bearings.
10.
When you are satisfied that the correct pre-load has
been set, remove the assembly from the transfer case.
Grease both sides of the gasket and insert the assembly
into the transfer case once again. Now take the rear
cover of the overdrive and offer it up to the mounted
front end. Slide the two halves together until they
mate with the selector shaft uppermost. Make sure the
large ‘O’ Ring is seated in the groove between
the two halves. Now secure the complete overdrive to
the transfer case using the six long bolts provided.
Note that there is a sealing washer on each bolt. The
bolts should be tightened firmly - but not excessively.
(On Discovery models where space is tight the two halves
should be assembled with the selector shaft at the bottom.
Once the rear cover is fully home it can be rotated
until the selector shaft is in the topmost position
before tightening the bolts).
 11.
This picture shows how the actuating
lever is attached to the Roverdrive. A flat ‘C’
plate, mounted to the top two transfer case bolts, supports
an ‘L’ bracket. The actuating lever is connected
to the overdrive by an adjustable turnbuckle.
 12.
Remove the two bolts that secure the
top of the transfer case to the gearbox. Secure the
‘C’ plate to the transfer case using the
same bolts. Now mount the ‘L’ bracket to
the ‘C’ plate using the 8mm bolts provided.
The arm of the ‘L’ points forward and on
the left hand side of the transfer case.
Examine the relationship of the ‘L’ bracket
to the inside of the tunnel cover. There is some variation
between different models of Land Rover in this area.
You will need to bend the ‘L’ bracket to
a favourable position. The side of the end of the ‘L’
bracket should be parallel to the closest side of the
transmission tunnel and there should be a 20mm gap between
the outer surface of the ‘L’ bracket and
the side of the transmission tunnel. In order to get
the twist in the ‘L’ bracket correct you
will have to remove it and replace it several times
and perform the bending using a vise and a large adjustable
spanner. Generally speaking the sides of the Defender
tunnel cover are more vertical than those of the Discovery
and less bending will be required. Bear in mind that
the position of your actuating lever is determined by
the position of the threaded hole in the ‘L’
bracket.
 13.
Once you are satisfied with the position
of the ‘L’ bracket drill a series of small
holes through the side of the tunnel cover at right
angles to the surface. It may take several tries but
what you are aiming to do is make a hole exactly in
the center of the lever hole in the ‘L’
Bracket. Once you have found this point enlarge this
hole using a 50mm (2”) hole saw as shown.
On left hand steered Defenders you may have to remove
and replace the hand brake lever to drill the hole as
the lever emerges between the hand brake boot and the
transmission tunnel, and there is very little space.
14.
MOUNTING THE LEVER
 The
lever assembly can now be mounted and the turnbuckle
connected between the lever and the overdrive. In the
RH steering Defender shown here, the lever has been
given a bend to the right to place it closer to the
driver. The turnbuckle should be adjusted to give the
most convenient movement to the lever. The cover plate
and dust cover have been mounted to the tunnel cover.
In this case the side if the transmission tunnel is
not flat but the aluminum cover plate is easily bent
to conform.
15.
FILLING WITH OIL
The transfer case can now be filled with 75-85 synthetic
gear oil to the level plug. An additional half litre
of oil should be put into the Roverdrive through the
filler plug on the top. On a Discovery it is difficult
to access the filler plug on the Roverdrive so an alternative
method of filling is used. Fill the transfer case to
level and put the transfer case shift lever in neutral.
Now run the engine in fourth gear with the Roverdrive
handle pulled aft. Run the engine at about 500 rpm for
five minutes. The Roverdrive will now be primed with
oil pumped from the transfer case. Shut the engine down
and refill the transfer case as far as the level plug.
Check the Roverdrive housing and transfer case for leaks.
The turnbuckle linkage should be greased at the pivot
points.
16.
USING
THE ROVERDRIVE
For normal driving about town or off-road the Roverdrive
should always be in the disengaged position with the
lever pulled back. Once on the highway at about 90 KPH
(60 mph) the Roverdrive can be engaged. To engage simply
depress the clutch and move the lever forward with a
steady deliberate motion. As you move the lever forward
you will feel two dedents. On the second dedent slowly
release the clutch while keeping forward pressure on
the lever. At this point the lever will slip forward
into gear and the Roverdrive will engage. To disengage
simply depress the clutch and move aft with a steady
deliberate motion. You can keep the Roverdrive engaged
and use 4th and 5th gear normally. In this case your
4th gear will have a higher ratio than normal. If you
miss a shift and hear the gears grating do not continue
to move the lever but go back to the ratio you just
left before trying again.
17.
MAINTAINANCE
After the first 1000 miles of use, drain the transfer
case and Roverdrive housings and replace the oil. Put
some grease on the linkages and check the tightness
of the mounting bolts. Change oil every 5000 miles thereafter
and follow the filling instructions above. Your Roverdrive
is virtually silent in operation. If your transfer case
gears are worn, however, the transfer case will produce
more noise on overrun than it did before. This is simply
because you have introduced a new gear to a worn one.
This noise reduces as the unit runs in but you may be
happier with a more viscous conventional oil and not
a synthetic for the first 5000 miles or so.
18.
A HANDY IMMOBILIZER
 The
Roverdrive has been designed with a built in immobilizer.
By adjusting the alignment of the lever pivot bolt you
will find that it is possible to slide a padlock through
the lever boss when the Roverdrive is in a neutral position.
This makes the vehicle impossible to drive away. After
using the immobilizer always return the Roverdrive to
the aft position before starting the engine. Do not
use this feature if you have a poor emergency brake
and rely on the gearing to stop the Land Rover from
rolling down an incline when parked.
|
