Thread: LT85 Gearbox

Originally Posted by Land-lord

Hi Team.

Santana supposedly produce the strongets box..... LT85? Is this correct?

If so, how do I make one fit the 186 in a S1 86" SWB?

THanks

With great difficulty. The gearboxes fitted to the RR, Disco, Stage 1, 90/110/Defender are not interchangeable with the gearboxes fitted to the other Series Landrovers. Bell Housings, dimensions etc are different, and perhaps a bigger problem is that they are all designed for full time four wheel drive, and the Series 1 front axle is not. I believe some have mated the LT77 or LT85 box to the Series transfer case, but it would involve a lot of design and engineering work. An alternative would be to convert the vehicle to full time four wheel drive by modifying or replacing the front axle, probably slightly more easily done, but problems include :-
Except for the Stage 1 axle (very rare), all other Landrover axles designed for full time four wheel drive are also designed for coil springs, and while this can be worked round, none of the work rounds are really very satisfactory (and many are downright dangerous).
The track of all of these axles (including the Stage 1) is significantly wider than the track of the Series 1.

Conclusion is, it could be done, but why would you go to all that trouble?

John

The LT85 is very strong but also very large (both length and diameter), and was only ever fitted to the V8 or the 4BD1 diesel. both of which have completely different bellhousing patterns to the 4cyl or 6cyl rover engines.

I doubt it would be possible to squeeze one into an 86". Even an LT95 with a (very short) 101FC bellhousing is a very tight fit.

John - the front axle in a series works fine in constant 4x4 without mods (early series tracta joints may not last long though). There are plenty of 4x4s with constant 4x4 and UJs.

Easy...

remove all body work...

remove existing engine and drive line...

Drop in said gearbox mated to its tcase with the 4BDI on the front of it..

drop the body work back on and beat it down with a sledge hammer or wrecking ball (carefull of the glass work and instrument panel on the dash) then get someone else to drive in front of you with the radiator and hoses in a trailer.

Seriously Id say it cant be done economically not saying it couldnt its just not worth it.

I did a quick measure up for putting it in a 109/88 back in 99/2000 and came to the conclusion that It might work in a LWB but then you have to uprate the diffs, axles and brakes to boot.

Originally Posted by isuzurover

John - the front axle in a series works fine in constant 4x4 without mods (early series tracta joints may not last long though). There are plenty of 4x4s with constant 4x4 and UJs.

That is an interesting comment. I have no experience of using cross and bearing joints with constant four wheel drive, but everyone I have seen commenting on it lists it as a problem. The problem is that when the steering is deflected significantly the speed of each wheel changes as the joint revolves. This is very noticeable with a Series in four wheel drive on hard surfaces, although not at small steering angles. And the centre diff would reduce the effect by spreading it to the rear wheels.

I know of no full time four wheel drive with simple cross and bearing joints. All current full time four wheel drives I can think of use Rzeppa joints, but I can't say I am familiar with all of them. Double cardan joints were used in front wheel drive vehicles such as the Citroen Light 15 and DS, but that is a different situation.

Tracta joints (not fitted to 86" Landrovers anyway) should stand up OK and have the advantage they are constant velocity, invented by Gregoire for the Tracta front wheel drive racing car, and the early 80" Landrover was full time four wheel drive anyway - the tracta joints were dropped when selectable four wheel drive was introduced.

John

Originally Posted by JDNSW

That is an interesting comment. I have no experience of using cross and bearing joints with constant four wheel drive, but everyone I have seen commenting on it lists it as a problem. The problem is that when the steering is deflected significantly the speed of each wheel changes as the joint revolves. This is very noticeable with a Series in four wheel drive on hard surfaces, although not at small steering angles. And the centre diff would reduce the effect by spreading it to the rear wheels.

I know of no full time four wheel drive with simple cross and bearing joints. All current full time four wheel drives I can think of use Rzeppa joints, but I can't say I am familiar with all of them. Double cardan joints were used in front wheel drive vehicles such as the Citroen Light 15 and DS, but that is a different situation.

Tracta joints (not fitted to 86" Landrovers anyway) should stand up OK and have the advantage they are constant velocity, invented by Gregoire for the Tracta front wheel drive racing car, and the early 80" Landrover was full time four wheel drive anyway - the tracta joints were dropped when selectable four wheel drive was introduced.

John

To first clear up the terminology - UJ = cardan = cross and bearing (never really heard that last one). Double cardan means 2x C&B/UJ/cardan joints together - which makes a CV joint.

Several models of 80's jeeps were full time 4x4 and had UJ/cardan/C&B joints - there may even be a model still in production, but I am not sure. I remember arguing the same point with some know-it-all from the Series II forum, and I posted on a US board (pirate4x4.com) asking owners of such jeeps to comment on how they drove. Can't find the thread (since non-paying members cannot search), but the response was that they drove and handled fine, and only had some slight steering feedback when heavy right foot and tight steering lock was used.

A couple of times when I broke rear axles in the IIA I drove it quite a long way in front wheel drive on the road without problems.

Originally Posted by isuzurover

To first clear up the terminology - UJ = cardan = cross and bearing (never really heard that last one). Double cardan means 2x C&B/UJ/cardan joints together - which makes a CV joint.

Several models of 80's jeeps were full time 4x4 and had UJ/cardan/C&B joints - there may even be a model still in production, but I am not sure. I remember arguing the same point with some know-it-all from the Series II forum, and I posted on a US board (pirate4x4.com) asking owners of such jeeps to comment on how they drove. Can't find the thread (since non-paying members cannot search), but the response was that they drove and handled fine, and only had some slight steering feedback when heavy right foot and tight steering lock was used.

A couple of times when I broke rear axles in the IIA I drove it quite a long way in front wheel drive on the road without problems.

I too have driven Series 2as with broken rear axles or diffs, and certainly they do better without the rear wheels driving, although I would not like to deal with the kickback on bitumen with sharp corners. I suspect the Jeeps you mention get away with it by having a viscous coupling to the front wheels, possibly set up to give only front wheel assist. I assume they also have power steering, which covers a lot of sins. A lot of early front and four wheel drive vehicles did use a simple cross and bearing, and this was the cause of a lot of their problems until the first CV joints were invented in the twenties. One way of getting round the problem was that used by the Jeffery Quad, which had a 1:1 crown wheel and pinion, with a 5:1 reduction gear in each hub, which not only allowed the use of a conventional kingpin, but because it meant the speed variations were about twenty times per revolution rather than four times, they could be damped out by the spring in the rather thin half shafts.
If you haven't already done so you may be interested in the article I wrote on U-joints in the just published Aulrovian.
Another interesting setup (not mentioned there as not relevant) is that I seem to remember one very early four wheel drive truck (or was it a tractor?) that avoided the U-joint question altogether by having the drive axle with a bevel gear onto the top of a shaft coaxial with the kingpin, which in turn had a bevel gear onto the stub axle. Mind you, I can see this giving some interesting steering effects too!

John

John - do you have a link to your article?

your terminology does not appear to be in common use:

A universal joint, U joint, Cardan joint, or Hardy-Spicer, Hooke's joint is a joint in a rigid rod that allows the rod to 'bend' in any direction. It consists of a pair of ordinary hinges located close together, but oriented at 90° relative to each other.
Contents

The concept of the universal joint is based on the design of gimbals, which have been in use since antiquity. One anticipation of the universal joint was its use by the Ancient Greeks on ballistae. The first person known to have suggested its use for transmitting motive power was Gerolamo Cardano, an Italian mathematician, in 1545, although it is unclear whether he produced a working model. Christopher Polhem later reinvented it and it was called "Polhem knot". In Europe, the device is often called the Cardan joint or Cardan shaft. Robert Hooke produced a working universal joint in 1676, giving rise to an alternative name, the Hooke's joint. It was the American car manufacturer Henry Ford who gave it the name universal joint.

The old Quadratrack jeeps had a BW1339 T-case, but I am pretty sure the centre diff split drive evenly F-R. I am pretty sure all/most jeeps had PAS.

Btw - I once locked my IIA in 4x4 to do some work on it, and then drove 30 miles (including some highway driving) to work on bitumen without realising until I was pulling into a carpark and I felt some feedback in the wheel. Back then it was a fairly standard 109 on 235/85/16 tyres.

Gees you guys love your Landies!