DIY VCU service

Alibro said:

To be honest I will be a bit paranoid about it for a while but as it only takes a couple of minutes to jack up a wheel and check if it still turns I will probably be doing that fairly frequently for a while If I were doing it again I would defo go for the thinner fluid, I think 60,000 would be fine for a car used 99% of the time on the road.

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So what are your thoughts on the 100k fluid?
Do you still feel the braking effect when turning corners/reversing etc.

Do the wheels try to skip when cornering on gravel surfaces?

Have you measured how hot the vcu gets with a normal straight run say 5 to 10 miles or so?

I used the 30k fluid which made all the above disappear...I still get enough drive from the rears to push the car forward on there own....but I too think a 60k fluid would have been the best comprise for road and off road use...

jedi said:

So what are your thoughts on the 100k fluid?
Do you still feel the braking effect when turning corners/reversing etc.

Do the wheels try to skip when cornering on gravel surfaces?

Have you measured how hot the vcu gets with a normal straight run say 5 to 10 miles or so?

I used the 30k fluid which made all the above disappear...I still get enough drive from the rears to push the car forward on there own....but I too think a 60k fluid would have been the best comprise for road and off road use...

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I haven't done enough miles to be able to answer all your questions but I do feel the braking effect at low speed on full lock.
I did a couple of miles yesterday including some on an old lane where the 4wd got a workout and when I got home the VCU was cold.

I agree though 60,000 was what I requested when I ordered the fluid and they sent me 100,000. I was in two minds whether to send it back or not but decided to give it a try.

It's probably what the stock LR vcu uses...That's what most say anyway about the 100k stuff....you'll probably be ok with it.

I just wanted to get rid of what I call the "chassis ripping effect" the transmission wind up etc...but still have enough drive to the rear wheels to stop the fronts scrabbling for grip and to get the hippo out of trouble...

So far it's been ok In snow n muddy fields etc...but I dunno about soft sand etc as that would require a bit more lockup/ stiffness.

As my VCU was pretty well solid I figured the drive train may have been weakened so that is why I wanted the 60,000 as I figured it would cause less strain. Am now thinking of getting some 30,000 and substituting 40 or 50% to see if it loosens things up a bit. I should be able to bleed it from one of the holes I've made and squirt the thinner stuff back in with a syringe.

I took the car out today for a 70 mile round trip including town, A road and motorway driving. It felt sooo much better than when Mondo mode as everything felt tighter. It was a wet day so I deliberately drove like a hooligan at junctions and round roundabouts and the car handled much better. No sign of the chronic understeer it had before.
The only issue was a slight vibration between 60 and 70 which I wasn't surprised about. Apart from the work I did and the dodgy welding I noticed the damper wasn't completely round. When I was testing the VCU for wobbliness after welding it together I spun it and found the VCU was fine but the damper had a wobble. Not sure how or why but it has three possible positions, I marked it before removing so I know it is in the right position but will try turning it to see if it helps.

The damper may have just taken a knock and been bent out of shape...I have heard people taking them off completely with no ill effects.

You've done well to weld it as straight as you have done.....I'm presuming it has to be near spot on for no vibrations.?

jedi said:

The damper may have just taken a knock and been bent out of shape...I have heard people taking them off completely with no ill effects.

You've done well to weld it as straight as you have done.....I'm presuming it has to be near spot on for no vibrations.?

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I guess so. I just jammed in four or five bits of cutting disk to space it before tack welding, then double checked by sliding a bit of disk all the way round.

I've been doing a lot of research about the VCU over the last few days and talking to some engineers who appear to know what they are talking about when it comes to these sorts of things - plus some that don't - there is a Thor on every forum. The Man of Many Hats has also been prodding these folk for info.

I'll post up here any conclusions that come out of it, but I came across a huge golden nugget of info today, I'll throw out here!

I was Googling all sorts of stuff related to viscous couplings and came across a thread on a Honda Civic forum - I didn't even know they did AWD. Anyways up there were some complete prats on that forum (eg someone had filled their VCU with engine oil) but some with a lot of sense.

They, like us, do not know how much fluid to put in the VCU. One fella thought up a really clever way of working it out...

As for the correct volume, this is what I did. The air in the coupler is intended to allow for thermal expansion without damaging the seals. I reasoned that the maximum temperature of the coupling must not exceed the maximum temperature for those seals. The Buna-n seals have a maximum temp of 240 deg. F., so I filled the VC completely, then placed it with the fill holes up and open in an oven heated to 200 deg. F. and let it soak for about 3 hours (until the Dimethicone stopped oozing out). I placed a catch pan underneath so Heidi wouldn't know I was using her oven. I then took the VC out of the oven, poured out just a little more to bring the level below the bottom of the fill hole, then let it cool overnight. The next morning I reinstalled the plugs in the fill holes. This SHOULD provide enough expansion space without going over.

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I'm not sure if this does create the correct air gap, but I can see the thinking behind it.

The full thread is https://www.civicwagon.com/archive/index.php/t-9747.html

GrumpyGel said:

plus some that don't - there is a Thor on every forum. The Man of Many Hats has also been ......

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How dare you put Thor & me in the same sentence, without at least one negative.

I can see the thinking behind the above, however my worry would be twofold....
1) the seals must be capable of taking a HIGHER temperature than the liquid.
2) by heating the liquid to (almost) the temperature that would degrade the seals, you risk degrading the fluid.

We believe??? the dilatant/PDMS fluid solidifies at circa 120-160C!

The Mad Hat Man said:

How dare you put Thor & me in the same sentence, without at least one negative.

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Wouldn't dare - there was a full stop between

The Mad Hat Man said:

I can see the thinking behind the above, however my worry would be twofold....
1) the seals must be capable of taking a HIGHER temperature than the liquid.
2) by heating the liquid to (almost) the temperature that would degrade the seals, you risk degrading the fluid.

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Well in that case we'll have to get Thor to get a Freelander and trial it on his - he can then tell us how much we need! Maybe not, he might start hanging out in the Freelander forum

why did landrover not use the honda one ,seems easy to fix that one

griff2 said:

why did landrover not use the honda one ,seems easy to fix that one

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https://www.youtube.com/watch?v=feD4D1quS0k

i had just watched that video, thats what i ment that looks so easy to fix ,why did landrover have to make the freelander vcu a sealed unit

the honda one seems simple to fix

Someone fancy knocking up a couple of adapters?

wonder if you could some how adapt them to fit? or would they be some how set different
maybe spin at a different speed to what the freelander one does?

griff2 said:

wonder if you could some how adapt them to fit? or would they be some how set different
maybe spin at a different speed to what the freelander one does?

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rotational speed doesnt matter - its difference across the VCU.

I thought it interesting he said to fill the VCU completely with no air space at all. Anybody any thoughts on this? He said the manufacturer confirmed it doesn't expand with heat. Unlike air of course which does.
He also didn't take much notice of the way the disks went back in. I was very careful to ensure mine went back exactly as they came out.

Somewhere I've seen someone claim that the disks tend to operate as pairs in the VCU and that they wear on the sides that are operating. Therefore there's an argument for putting them back in a different order or turning them round or something. Damn simple things but so much info from people who don't really know for sure, that everything gets confusing in the end.

There was no sign of wear on mine, not sure how they would wear with silicone between each disk, but they were fitted so that every other one lined up. It meant before pouring in the fluid I could see through the slots at certain points to the end of the VCU if I turned it slowly.
Not sure how important that is but I guess if nothing else it provides a path for the fluid to be squirted in at the factory.

GrumpyGel said:

Somewhere I've seen someone claim that the disks tend to operate as pairs in the VCU and that they wear on the sides that are operating. Therefore there's an argument for putting them back in a different order or turning them round or something. Damn simple things but so much info from people who don't really know for sure, that everything gets confusing in the end.

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Multiple disks cannot operate as pairs, if the gap between plates is identical.

Has anyone checked the plate alignment prior to removal?

The more we discuss this, the more it seems we dont know .

The Mad Hat Man said:

Multiple disks cannot operate as pairs, if the gap between plates is identical.

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Agreed, They are separated by a thin film of fluid with nothing mechanical holding them apart.

The Mad Hat Man said:

Has anyone checked the plate alignment prior to removal?

The more we discuss this, the more it seems we dont know .

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Ehmmm, I thought that was what I said I had done. After taking the top off I carefully marked the first 10 or so I removed and found they all followed the same pattern.