There's a long thread on here somewhere have a search.

It is switchable, but only by the ECU under braking as designed.

It is possible to put a switch in the clutch circuit to make it manually switchable.

 

Had a search but didnt see anything. 500 results too! Any ideas what the thread was called?

 

Try username Chip, it may have been him that started it.

 

think it was qrew that started it.

it's a clutchpack, hyudraulically actuated by an accumulator in the engine bay that shares PAS fluid. This engages the centre diff, which is a viscous coupling (i.e. different rotational speeds make it lock together).

Or the alternate answer is, 'it doesn't'.

 

The 4x4 transfer box drives the rear wheels drive through a so called plate clutch that gets actuated by the hydrolic pressure from the PS pump /accumulator, the pressure itself is actuated by an electrical solinoid valve to lock the plate clutch , this of course can be manually overridden if so desired by operating the solinoid valve electrically through a switch. , and the viscous coupling is there to take up any slack or drift between the front and rear speed differentials due to different tyre threads and also due to driffent grip levels the viscous coupling is where the engine power decides where to go more, ie more to rear or more to front, depending on the traction but is also designed to drive all 4 wheels even when the traction is equal on all 4 wheels, therefore the viscous coupling controls the amount of power to the rear wheels, which is designed deliberately bias more to the rear wheels than the front ones in order to create the differential so that the viscous coupling can work properly when it is heated up due to the differntial speed in the viscous fluid, if the he viscous coupling was not loaded properly then nearly all of the power from the engine may go either to the front or the rear depending on the loading given by the manufacturers, so if the viscous coupling has a larger differential speed between the rear & the front then more power is distributed to the side that is gripping more and less to the side that is spinniing (loss of traction) This is what I read on 4x4 transmission and is being summed up here.

 

usefull 4x4 transmission link here:
http://www.members.lycos.co.uk/maxboost/htms/4x4description.htm

 

That's an awesome link!

 

lol at tathan "it doesn't"

Thanks for replys guys.

Complicated enough!!

Cheers MSG!

 

it's fairly simple tbh, i've seen worse. it's only the spaz-proof disengagement of the 4wd during braking that makes it non-agricultural.