Hippo FWD?

How does it work then?

do yu mean front wheel drive or four wheel drive?

they put one leg in front of the other and walk

howardo said:

they put one leg in front of the other and walk

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nasty man - taking the micheal out of the poor freelander owners - yu will get told of by How......................... oops!

Apologies........Four wheel drive

Oh.................. and everyone else...............



**** off a minute, Im about to get a proper answer :mooning:

4wd is like 2wd - engine thru gearbox to diff and both front wheels.
difference is that the manufacturer fits onother differential called an IRD after the gearbox, so it allows another take-off towards the rear wheels. on the Hippoo the coupling between the IRD and the rear diff is done by a peculiar locking system called the VCU which is full of liquid which changes its viscosity (drag) with the heat generated by the difference in turning of the blades attached to the front half and the blades attached to the rear half.

So.............if the front wheels lose traction, the front blades spin faster, the oil thickens and the rear wheels are engaged through the friction created?

simply put - yes.

So loss of traction HAS to occur for four wheel drive to engage? How instant (or not) is it?

and thanks for your patience and answers so far

no
it is more complicated than that.
it could occur because of loss of traction to one wheel, different tyre sizes, degradation in the viscous fluid and a few other reasons. That is why it is considered by some on here to be a poor system. Especially as, when it does lock up, if driven on non-slippy surfaces it will wind up the transmission until something goes bang. Landrover, in their infinite wisdom decided that, rather than fitting a "weak link", they would allow the IRD to be, invariably, the first thing to go BANG!, thereby resulting in a rather expensive repair build.

Ah.....things become clearer, well thankyou for all the answers, what a bluddy nice chap.

While Ive been waiting I ve been surfing other places to find out stuff. Even if its crap, its still interesting stuff. Thankyou

Lochen said:

How instant (or not) is it?

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depends on the condition of your vcu, but was p*ssing about in the snow and ice for exactly this reason, trying to make sure that mine did indeed lock up, and as far as I can tell, it was nigh on instantaneous.

(and no it's not seized solid before you ask, well not yet anyway, sure it's just a matter of time)

Every body seems to think that vcu,s lock up becuse of the heat of the fluid, that is a lot of crap, the viscus fluid is a non newtonian fluid, it is not afected by heat of cold, if you have seen the old trick of walking on custard you will see how it works, the fluid is made by Dow-corning, but is hard to get in the uk, if someone can find a sorce the we can change the fluid in our vcu and save a lot of money, the fluid is sold in 3 grades so it should be possable to adjust the amount of rear drive

Yeah - we know that - but the OP wanted a simple explanation. My description was incorrect on a couple of points, but served to explain the system, simply.

nongrokal said:

Every body seems to think that vcu,s lock up becuse of the heat of the fluid, that is a lot of crap, the viscus fluid is a non newtonian fluid, it is not afected by heat of cold, if you have seen the old trick of walking on custard you will see how it works, the fluid is made by Dow-corning, but is hard to get in the uk, if someone can find a sorce the we can change the fluid in our vcu and save a lot of money, the fluid is sold in 3 grades so it should be possable to adjust the amount of rear drive

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Is the VCU fluid the same stuff that is used in radiator fan viscous couplings?

jonaf said:

Is the VCU fluid the same stuff that is used in radiator fan viscous couplings?

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No! cos that get's thicker and locks the fan up with heat!

nongrokal said:

Every body seems to think that vcu,s lock up becuse of the heat of the fluid, that is a lot of crap, the viscus fluid is a non newtonian fluid, it is not afected by heat of cold, if you have seen the old trick of walking on custard you will see how it works, the fluid is made by Dow-corning, but is hard to get in the uk, if someone can find a sorce the we can change the fluid in our vcu and save a lot of money, the fluid is sold in 3 grades so it should be possable to adjust the amount of rear drive

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Now we are getting somewhere:
Automotive Solutions - Automotive Lubrication - Dow Corning
The three grades are 3-9160 | 3-9161 | 3-9162

The products are not available in Scandinavia. I have sent a request to the company about product details and availability.

I have compared my vcu with a brand new unit. My old one was about twice as heavy to twist. I think it may be possible to drill out the steel balls in the holes on each side of the vcu to drain/refill it.