DIY VCU service

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jedi said:
So turning it slowly it will turn forever. ...but as soon as you fire up the beans in less than a turn you can feel the vcu stiffening/locking up....

Can you explain how you did this just out of interest, I might have missed something....all info is welcomed:)
Click to expand...

The VCU never locks up solid, it doesn't work that way.
What it does is transfer torque from one side to the other. The more torque that is required, the more it passes. It will always slip a bit or it won't work.

So the only test that can be done without expensive test gear, is a load / time test.
Effectively a know load is applied and the time for the VCU to rotate X number of degrees is recorded.
The longer the time, the stiffer, or the more torque the VCU can transfer.
 
Funny you should have posted this Nodge as ive just found this from what looks like ashcroft transmissions....see last post in the link...

I too would have liked it to be just a viscosity thing...but in vw world they reference the lock up...and in other stuff ive read (GKN) they refer to it as hump mode...?

Confused?

http://forum.difflock.com/viewtopic.php?p=311020

This is the GKN pdf on an LSD diff which I presume the viscous part is similar to a Freelander vcu. ..think ive posted this before..

http://www.gkn.com/driveline/our-s...upling/Documents/datasheets/Viscous-engl.pdf


The faster you apply torque to a vcu the faster it should stiffen up....I felt this on my origional vcu. What I have at the minute is a constant resistance..even when I turn it faster I still have the same resistance, which would move the rear wheels....what I dont know is whether it would get stiffer if it rotated a faster...can only test this on the car...

I could just fit it...I could still fill and drain in situ, but it would be a bit more awkward. .
 
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I came across this:

From www.landroverclub.com.ar • Ver Tema - SILICONA PARA REPARACION DEL VISCOSO DE LA FREELANDER

Two reports of what they did

1. 65% of 12500 cst silicone oil (120 milliliters)to 35% of 1000 cst oil (60 milliliters (ml)
2. 80% of 12500 cst silicone oil to 20% of 1000 cst oil

In here
www.landroverclub.com.ar • Ver Tema - Viscoso reparado.

He mentioned his VCU does not have a volume of 220 ml, but instead of 180 ml in which he was able to put 144 ml of the 80/20 mix
 
That sounds about right im at around the 150mm mark...and im struggling to get any more in...gona let it settled over night and try again. .

Thanks for the links
 
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jedi said:
That sounds about right im at around the 150mm mark...and im struggling to get any more in...gona let it settled over night and try again. .

Thanks for the links
Click to expand...
i am sure i read on a post some time ago it was 160-165ml so your not far off the mark as it has to has some air in the vcu as well
Ron
 
Gone very quite here since spin of test car sitting on my trailer untouched, Mind you temp in the 40s nothing much gets done in August,
 
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Im tarting my vcu up with my favourite black hammerite...fitting new bearings to it, ready to go back on the trusty hippo ready for winter:)

I cant get anymore fluid into it....its full.

I still dont get lock up on the bench, but can only manage about half a turn....Maybe origional fluid is thicker than the 30k I used...but loose is what I wanted;)

Maybe on the car if the vcu slips quickly 1 or 2 rotations it will stiffen up....thats what im hopeing for.....if not the rear should still get drive......it will be better than mondo mode anyway....

Will try and make a bench test video similar to bells.....in memory of my vcu:)

Its been emotional mr vcu, but now its time to go back where you belong:cool:
 
The Mad Hat Man said:
Do NOT fill the VCU. An air gap is crucial to it working correctly.
Click to expand...
I know but.....it might not be completely filled for all I know?.....I just cant get any more in?

I can aways drain some out if need be....

I would have thought with it totally filled I should feel it stiffening up? But nope.. Either im not spinning it fast enough or the fluid is too thin...

But with a faster spin im hoping it will start doing its magic:)


Ive gone as far as I can go now on the bench...will do some time vs weight test videos then its going back on the hippo...;)

Unless anyone has any suggestions before I do?
 
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I have an objection to you fitting it to your car..... Send it to me I will test it for ya
 
Well finally fitted it, bit of a delay as I noticed the front diff bracket had torn so had to wait for a new un:)

Now the verdict:

Drives very well no extra noises or vibrations from standard mondo mode.

Not too much feeling of any tightening up doing 360 turns either forward or in reverse..if you really look for it I would say you can slightly feel some resistance..but nothing like it was, im happy with this aspect of the vcu..on the bench it started to stiffen up considerably the more fluid I added, but now its on the car, id say it's spot on for saving the transmission parts. :)

A spirited 15 mile drive on A roads and motorway with un matched front and rear tyres :eek: seemed ok too...the vcu read 15c when I set of from cold and 19c when I got back.. So ok in that department. ...so far anyway;)

Now for the main part, does it give drive to the rears?

Well yes its does from what little testing I could do, will have to wait for some wet weather and test on a field as on a dry one I cant really tell.

I did however jack up the front end so that the front wheels where up in the air with a trolly jack...put the car in gear and there was enough drive from the rears to push the trolly jack forward with only around 1.5k revs, The more I reved the more it wanted to go forward, so ok here too, didnt want to push it too much as I could feel the jack slipping. The vcu read 60c at this point and was hot to the touch.

Conclusion:

All in all I am really happy with the way it's turned out. It's a loose vcu which is what I wanted, but still has enough rear drive to hopefully pull me out of light mud and more importantly get the hippo up a snowy hill, when the winter comes..

Will do more testing when the weather gets worse:) Its usually the other way round. ..
 
Excellent news, congratulations on your diy freelander vcu service that's a successful one. Now using this thread as a step by step guide I will commence my in a couple of weeks time and see if I can match your results, tho I think I would like a slightly stiffer vcu as I intend to use my car off the road a bit

Nice one
 
I think with a thicker fluid you should be ok......mine is quite loose. ...try a 60k cts, but again this all depends how much old fluid you get out, if your mixing with old then a 30k cts may be ok? I totally drained mine so I could turn it by hand, that was my baseline.

On the fluid sellers feedback there's a comment saying that the 100k cts that he bought was like the stock freelander vcu feel?......was that anyone on here?

If I do another one I will try thicker fluid, but its a trade off between transmission wind up and rear drive in my opinion.

Getting the old fluid out is the time consuming part...Think I left mine draining for 2 week s on and off....but I supose with and air line and suction this can be speeded up. :eek:
 
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I have a second vcu that I'm going to do so it can sit and drain for as long as it takes plus airlines at work pillar drill etc etc the place next door has a decent size lathe so I could split and re weld the case but it would take a fair amount of jigging and the possibility or needing a balance after is a little high, your offset drain and fill points cancel out the need for a re balance
 
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