Freelander 1 VCU

Everything you need is in the Freelander torque test thread.
https://www.landyzone.co.uk/land-rover/vcu-torque-test-results.109486/page-41
It's a long read and the abuse gets tedious at times but the information in it is a must know for a Freelander 1 owner.

AFS1 said:

Firstly, no it is not a Troll post.
Secondly, it might have been done to death, but there appears to be no definitive answer...... hence why it gets resurrected.
Thirdly, thought this might be in the wrong forum, as it affects other models of LR........
Fourthly, same comment as in in second paragraph.
Fifthly, without knowing exactly how theVCU works, I assume it turns with the propshaft, so if the gloop inside is thickening up, then I'd assume it might get warm / hot. So also assumed at some point that the VCU packs up whilst driving - so what happens, does the VCU disintegrate, does it lock-up, does it just stop send drive to the back wheels - I don't know, that's why I asked!
Sixthly, perhaps I'm being optimistic, but was hoping someone may well have some sort of answer. If you read everything that's around concerning VCUs it moves from 'then last forever, mines done 200k, to load of crap, mine only did 30k, to I'm paranoid about it, so changed it - even though it didn't need doing! At £200 to £700 that's a lot of money for a 'service item'!
Seventhly, no this isn't a troll post - "why is it apparent", because I read it somewhere (Bell Engineering) who says the OWUT doesn't work, who's to say that they know what they are talking about though.
And finally, I did think before I posted, you may not like it, but WHO THE HELL ARE YOU............

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Einly : Cool

Zweily : You will never get a definitive answer - there are to many different views on the subject. It is one of those where you have to read up and make your own educated option. If you find something new that adds to the mix, it will be great to hear about it - you will probably get shot down in flames - so it really depends on how many agree with you as to whether it was worth posting.

Dreily : Doesn't affect other forums - only of use with F1. RR does have a viscous center diff, but it works very very differently.

Vierly : Dodged

Fünfly : Do a search on LZ and the WEB, there is plenty that tells you basically how the VCU works and basically what goes wrong - it seriously is not worth another thread.

Sechsly : You state you want an answer, then you go and state what the answer is - they last different lengths of time, the reason for the differences unknown (but there will be vocal opinions no doubt). £200 for a service item isn't that expensive. It'll cost twice that much for a set of tyres. How much for a clutch/flywheel fitted? Over the VCU's lifetime there will probably be more money spent on items for the TD4 fuelling system that should be considered "service items" (like everything related to it).

Siebenly : Cool (again - see how repetitive VCU threads are!). Bells make great recon VCUs - I don't think that is in doubt by anyone. Whether they spout rubbish on their website is very much open to debate - and most people on the forum do think it is just that rubbish. I believe so strongly that what they say is crap that I asked on an engineering forum whether the OWUT is a justified test of the VCU and the the members on there agreed that it is a perfectly good test that will be within the limits of diagnosing problems. So "who's to say that they know what they are talking about" - basically them and you and a couple of others, most people, including engineers, believe they talk rubbish.

Und finally, you do need to search some more and think about it - you don't need to spend to much time on it, a quick Google will pop up a few pages that will give you loads of info. I feel the VCU threads on here are not a good place to initially find info - there are too many opposing views.

Who sind me : I, like you, and everyone that posts about the VCU, started somewhere. You're thankfully starting before you let your transmission cook itself. So you shouldn't let it happen. I only started thinking about it after my transmission imploded, which was why I joined LZ. I was very ****ed with my Freelander and peeps on here were saying stuff about the VCU that I questioned and got shot down in flames. So I studied it, analysed it and came to my conclusions - which are of course perfectly wrong, as are everybody else's. Nobody really knows everything about VCUs - especially failing VCUs, you have to know enough to get by with and not let it destroy your transmission.

Skinny Mike said:

Bit of a delicate issue at the Mo. Don't get wound up by @GrumpyGel , he's just making sure your not trolling. We've had a bit of a problem lately.

But if I'm correct, your from the Freelander Facebook group, so pretty sure your sincere.

I'm in the "reverse it in circles camp" it's bleeding obvious if your vcu has died. It'll lock up or feel like the brakes are full on.
Also when you've been on a long drive, it'll be red hot, it should be warm to slightly hot.

I don't discount the OWUT. But believe I can spot a problem before having to do this. I'm fortunate in that I've had my Freelander a very long time and know it's little quirks very well.

As said, there is no definitive test, but if you check all the other components it could be, brakes etc, and they are ok, then it's your vcu.

Mike

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Another 1 to break down.....

Skinny Mike said:

Bit of a delicate issue at the Mo. Don't get wound up by @GrumpyGel , he's just making sure your not trolling. We've had a bit of a problem lately.

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Plus, I'm just bloody Grumpy

Skinny Mike said:

But if I'm correct, your from the Freelander Facebook group, so pretty sure your sincere.

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Is that just the Ejuts Group, or the Official Ejuts Group?

Skinny Mike said:

I'm in the "reverse it in circles camp" it's bleeding obvious if your vcu has died. It'll lock up or feel like the brakes are full on.

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Mine didn't feel to bad, only scuffed on gravel, little braking affect - still totaled the transmission. You're also saying that other members here can't pick up on the bleeding obvious.

Skinny Mike said:

Also when you've been on a long drive, it'll be red hot, it should be warm to slightly hot.

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Is that right? I'm not so sure, I get easily confused these days !

Skinny Mike said:

I don't discount the OWUT. But believe I can spot a problem before having to do this. I'm fortunate in that I've had my Freelander a very long time and know it's little quirks very well.

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I believe I am a babe magnet.

Skinny Mike said:

As said, there is no definitive test, but if you check all the other components it could be, brakes etc, and they are ok, then it's your vcu.

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I had a light out on my motor. I checked every other component out, as you say brakes etc, with every other component checked out and with just the bulb left to check - I deduced that it wasn't worth checking it - it must be the bulb.

I am seriously Grumpy on this thread - pick the decent bits out !

GrumpyGel said:

Another 1 to break down.....



Plus, I'm just bloody Grumpy



Is that just the Ejuts Group, or the Official Ejuts Group?



Mine didn't feel to bad, only scuffed on gravel, little braking affect - still totaled the transmission. You're also saying that other members here can't pick up on the bleeding obvious.



Is that right? I'm not so sure, I get easily confused these days !



I believe I am a babe magnet.



I had a light out on my motor. I checked every other component out, as you say brakes etc, with every other component checked out and with just the bulb left to check - I deduced that it wasn't worth checking it - it must be the bulb.

I am seriously Grumpy on this thread - pick the decent bits out !

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Yes, you are the world's grumpiest babe magnet

Personally, im never quite sure what all the fuss is about. If you think it's fooked, replace it.
As you said, it's cheaper than a set of tyres.
Says he who has god like powers and still has a perfectly functional original vcu. It'll break now

Mike

I actually believe that the OWUT is a worthwhile and valid test for an un bodged VCU.
The OWUT is actually no different to the test that Bell use. The only difference is, they test it in a vise and turn it directly with a weighted lever, which obviously requires the VCU to be off the vehicle. I don't know why Austin (from Bell) dismisses our test, when it's effectively the same as there own.
The OWUT doesn't test the VCU for function, nor does the Bell test. What it does do is give an indication that the fluid has begun to thicken. Now the mechanisms of VCU are far too long winded for this thread and are always up for considerable debate anyway. But what we do know is:
A working VCU has two states. The free turning state, (there is some minimal drag). This is where it will just slowly turn while fitted in the drive train. In this state, it is passing little torque and because of the drive train design, shouldn't pass much torque.

The other state is known as hump mode. This is where the fluid transfers much more torque by thickening with agitation. Now the actual mechanism to start hump mode is still a cause for debate. But whatever the mechanism, it still thickens. However hump mode is where the Freelander's drive train damage potentially occurs. What triggers hump mode is known, but only in a new unit. Hump mode will happen at 75 Rpm with ~400Nm of torque passing through it.
It appears however that as the fluid degrades with age, hump mode becomes easier to achieve. This is bad as the torque transfer can become considerable. This is obviously undesirable, when driving down the street.
So what the OWUT does is test for fluid degradation (thickening) without putting the VCU into hump mode.
The problem with early hump mode onset is this. It basically reduces the safety margin built into the VCU to compensate for cornering and slight tyre mismatch. Once this reduced safety margin has been exceeded, the VCU starts transferring torque all the time.
So for example, the VCU is old with little margin until it achieves hump mode. Now you get a slow puncture in a rear tyre while you are on a 100 mile drive on the M1 at 70. The front and rear propshaft will rotate at different rates because the rolling radius of the tyres has changed. This difference is enough to cause early onset hump mode (torque transfer) to start. Now the IRD and rear diff are taking high torque as the VCU is trying to equalise the rotational difference, but the tyres won't slip to lessen the load. This massively overloads both the IRD and rear diff one of which will fail.

This is my analysis of the failure mode of the VCU. It may not 100% correct, but I believe it's accurate enough for our needs.

So by checking the time on the OWUT, we get a guide as to the state of the fluid. The thicker the fluid, the earlier hump mode occurs. The earlier hump mode occurs, the less tolerance there is for tyre mismatch.

Edited to improve information given.