Thread: Gear box change

Are the 6x6's fitted with lower diffs than the 4x4's?

Mick.

Originally Posted by Perentie Brad

Hi
I have a 110 6 X 6 and would like to change the gearbox from the LT95 to a LT 85 or other box to pick up a fifth gear for the highway, has anyone done this before or know if it is possible?
Any advice or help would be appreciated.
Brad

Not feasible Brad. You just can't slot in a 5 speed without a lot of work. Main reason is the rear axle drive unit is made specifically to fit the LT95 4 speed that is in it. If you want to get rid of the drive to the rear axle you can fit the 5 speed no hassles. Other thing to consider is the winch PTO if you have one fitted. This also comes off the LT95 transfer and will not fit the LT230 transfer which is fitted to all 5 speed boxes. Only way I know of that it could be done (with a lot of expense and time I imagine) would be to use the Isuzu MSA truck gearbox (5 or 6 speed) and engineer it to fit the LT95 transfer. This also would have to be cut off the gearbox as in the LT95 box there is one housing for both gearbox and transfer, not 2 piece like the 5 speed setups. Some others have changed diff ratios from 4.7 to 3.5 which then gives it the same speed capability as the 4X4's. Personally I reckon 4.1 would be the better ratio for it given the tare weight. Quite a few on here have gone the MSA to LT230 way, but there has been problems with the adaptor shaft. Whichever way you look at it is going to expensive!! Have a search on here and do a bit of reading up! I can do 90k happily on the highway with mine.

As Bearman says, the LT95 gearbox is integral with the transfer case and is the only transfer case made by Landrover (or anyone else) that has provision for a PTO output that turns at the same speed as the main rear output. It was designed specifically for the Landrover 101, which was designed to have a powered trailer.

The only way that a five speed box can be fitted is to cut the transfer case off the LT95 and design a setup to mate it to another gearbox. This has been done, but as it is a one off, expect the cost to run into five figures (unless you have the skills and facilities to do the design, machining etc), and take many months. An alternative would be to design and fabricate an alternative PTO, perhaps on the front of the forward rear diff, but at first glance this would be an even more formidable undertaking.

John

I have personally seen two LT230 to MSA failures and both were caused by the adaptor case failure transferring bending stresses to the shafts .If the case is built properly and in true alignment the shaft made of suitable material and heat treated it will be stronger than the original and perfectly adequate

Noel

Thanks Bearman, JDNSW and Ancient Mariner,
When it comes down to it, the intended use of the vehicle is holidays so why rush, it does 100kph but is happier at 80.
If there was a simple solution I would do it but it will stay a 4 speed, was never a problem when I was was driving them for work as convoy speed was never above 80 kph