4wd problems

I am glad you agreed with the maths, that at least proves that driving in a straight line can be damaging. Also, as I pointed out, driving a curve is also detrimental as that just increases the problem.
My comment relating to Land-Rovers did not include post 80's models as the previous series 1-3 did not have center diffs. at least in production.
There are many reasons why a half shaft can snap, twisting being the most obvious but the ones I have seen exhibit this phenomenon over a period of time due, probably, to poor material of inadequate strength and design and probably wind up caused by the driver not realising how much damage will be caused. From my own experience of RTV trials, many Land -Rover drivers regularly abused their mounts and replied to criticism "oh it will be ok" and when something broke they came up with every excuse other than driver error.
Now I have made my point and will leave the other members to make their own decisions.

Roger

Glad that argument is done with.
I don't want to start another but it seems to me that the old style 4 wd as in Jimnys, old landies etc with part time 2wd and no centre diff all have a major flaw. If you are driving on mixed surfaces, that is soft one minute then hard the next you run the risk of wind up or you have to keep shifting out of 4wd. That system is also fairly useless for driving on icy roads where you don't know the ice is there until you are dancing on it. I guess that's why landrover went to permanent 4 x 4 with centre diff. That system however also has a major flaw which is why they include a diff lock thereby putting you back in to much the same situation as before.
I would love to see a jimny with permanent 4wd and a centre diff (ala defender) but with all 3 diffs being limited slip. I reckon they would be unbeatable.
I would prefer that to all the electronic gizmos that pack up as soon as you sniff at them (ala modern landies like rangees and disco's electronic shift jimny's etc).
There you go folks, I have lit the touch paper.
Ps This is not about jimny over landies, I have owned a series 3 landie and a defender and SJ413 and currently Jimny.
They all have their qualities and faults/limitations. All engineering designs are a form of compromise. You pays your money and make your choice.

A viscous coupling, as used in Freelanders and many other AWD systems, achieves a similar result to an LSD in the centre diff would. There has been some discussion on here about running one in the front prop on a Jimny. This would allow you to run in 4wd all the time.

Sounds possible in theory, However I have heard complaints about freelander and other vehicles that use similar systems that there are problems with them.
One being that they have a tendancy to lock up, and another is low spread and cornering drag. I wonder if it would be too detrimental to the fuel consumption on a small engine vehicle like a jimny (already known to be a tad thirsty).
I suspect the extra weight and drag from the set up I suggested might also cause the fuel consumption to go beyond reasonable. So maybe some brave soul needs to experiment. Anyway I was thinking really about offroaders more than normal use on road. It would be interesting to see both set ups side by side.

As Lambert said, in my experience the lack of a viscous couplng and permanent 4WD is no big issue. In fact for me it's a bonus, even less to go wrong. The Jimny has the edge over my Series Land Rover due to its ability to engage 4WD on the move, button on 4WD, button off, easy.
I tend to drive everywhere and on any surface in 2WD, only engaging 4WD if I get stuck or feel control is diminished (snow / ice), then back to 2WD as soon as possible.
As a consequence I have never experienced any issues as I spend the majority of time in 2WD, even off road.

Edit - I did accidentally leave my Series Land Rover in 4WD and went for a drive. Instantly knew something was wrong, steering felt strange. 2 miles later whilst still trying to figure out what was wrong, the Land rover literally jumped into the air with a sonic bang. At this point the penny dropped, luckily no damage.

The viscous coupling would simply provide the means to reliably use 4wd in changng conditions. You would still use 2wd for the vast majority of the time, so reduced fuel economy and wear on the coupling wouldn't really come into it
The viscous couplings themselves are just a small block that would be integrated into the front prop so there's no significant weight gain or added complexity. If it did lock up then you'd be back to standard Jimny 4wd operation.
Anyway, it's just an idea I had. I might make one someday if I come across the right ingredients.

Re the Stalwart comment..yep wind up was a proper danger, I saw a lad thrown across the vehicle park after he jacked up one side to change a wheel ....he had been told to bounce it off the kerb first but thought he was being initiated as he was new to the sqn ..He learned though. Now that was a go anywhere vehicle !

You have a point, Less is sometimes better (mostly in my experience).

Series landies , if memory serves me also used to strip half shaft splines regular as clockwork. I think they changed the splines more than once to try to cure it.
As for Rogers comment about drivers abusing their mounts, I thought that was Standard practice for landies back then. If the condition of S/H landies back in the day was anything to go by it must have been mandatory.

Re viscous couplings, The idea certainly has merit. Could wind still up be a potential problem if you were say pulling hard uphill on a bend? The coupling still has an element of drag as far as I am aware. A bit of caution may still be required?

Agreed, its not actually a problem, Just a bit of a pain having that extra stuff to think about. I was just posing an idea that would make driving simpler without losing the benefit of 4wd.
Torque biasing diffs or limited slip diffs have the benefit of improving traction without any input from the driver. They are a relatively simple mechanism wholly within the axle casing with no external parts required. Whilst allowing normal driving. If used in a centre diff, windup would be a thing of the past unless you were seriously abusing it. In which case you would probably go for diff locks anyway or choose a motor without a centre diff.
All with NO electronics to fail.

The viscous coupling would definitely allow enough slip to avoid any windup. That is precisely why they are used in the applications they are. An AWD vehicle with a viscous coupling essentiually behaves as a 2wd vehicle until that axle loses traction.
For a serious off-road use it would be detrimental but for the vast majority of Jimny users it would be a massve benefit.