Quick question on the VCU

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Hard-Drive

Hard-Drive

Active Member
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First post in this section I think so go easy on me! I'm a Defender driver but the Mrs has a Freelander 1 TD4 HSE which I got MOT'd yesterday.

Now, I understand the VCU system in principle. I've been wary of a failure, and yes the car does "scrub" a bit on full lock, however in a previous issue of LRO it said this is normal, and you should only be concerned if the steering starts not self-centering at 30mph. So I wasn't worried.

However, when the car was on the ramps. I had a fiddle. The front wheels were on the ramp, the rears elevated. The MOT tester was holding one rear wheel, and I tried to spin the other. Now I was expecting his to stay still, mine to spin as I turned it, and the rear prop to spin a bit before the VCU probably locked up.

However there was no movement in the VCU at all, and me and the MOT tester were basically just working against each other on the rear diff.

That's bad, right, and it needs a new VCU? My other idea was to put some Tippex marks on both sides of the VCU, and go for a short drive on tarmac, and again if those lines are still lined up, that's bad too, right?

Thanks in advance. Sorry if this has been done to death already...I had a quick look at the "VCU Torque Settings" thread but it had "escalated" somewhat by the end of page 1 so I gave up!
 
Do the OWUT as linked by Hippo. However you can't turn the front and rear wheels independently, except for very slowly. If they don't turn slowly and you're getting scrubbing. Then it's better to play safe and remove the VCU.
Have you been maintaining the tyres correctly? Ie, same make, type and size all round. Least worn on the rear and always keeping the pressures correct?
Tyre maintenance is vital for long VCU life.
 
Your experience at the MOT station is probably what is to be expected.

There is a lot of chat about Freelander being 2WD until the fronts lose grip and then the VCU kicks in and drives the rears. This sort of makes it sound like the VCU should free-wheel at low speeds, but that is not the case. If you get a new VCU and try and turn the ends you won't be able to. If you put some levers on them you will be able to turn it, but very slowly (speed depending on the lever length I suppose).

A good time on the OWUT (1.2m bar, 5kg weight, 1/4 turn of the wheel, 0.8 turn of the VCU) is 30 seconds - so this shows the forces it dealing with basically "at rest".

Your experience of wheel scrubbing when driving is definitely NOT what you should be experiencing. The wheels should not scrub on tarmac - grip from the tyres should force the VCU to slip. Scrubbing on loose surfaces, like uneven gravel can be expected where there is less grip.

I would also STRONGLY recommend that you do the OWUT. With a 1.2M bar with 5kg weight is what people are testing against here. If you get a time over 90 seconds (or is it 2 minutes!) then whip the props off and get a replacement new GKN unit or a recon from a reputable source (eg Bells).
davidsmith1307 said:
You are a brave man starting this thread.
I predict nuclear war within 24 hours.....
Click to expand...
lol, there is no such thing as a "Quick question on the VCU"!
 
Just to give a bit of indication, my FL1 does stiffen up in tight turns, it's permanent 4 wheel drive, it will. But no tyre scrubbing or skipping. my OWUT comes out around 45/50 secs with 5kg at 1.2m.

With the Gearbox in neutral and off the floor, you should be able to push both rear tyres in the same direction to turn the prop shaft. This has nothing to do with the VCU.
 
Guys

Thanks very much for the replies. Yes, I think I'd totally misunderstood how the VCU works...I think I was expecting a similar result to how my Defender would have behaved in a similar situation (assuming that we imagine the Hippo VCU and the 'Fender transfer box are doing the same job for a moment...I appreciate they don't in practice). I'd have expected the back prop (from the VCU backwards) spinning merrily away as I span the wheel one handed, and the front part static. I thought the VCU would be as slippy as a viscous fan coupling, that's obviously not the case at all. I'll try the OWUT and see what results I get.

The tyres are all identical, however I will check the tread depth, however it's very close indeed and I'll need to put a depth gauge on it for an accurate reading so probably of negligible importance.

Two other important bits of info I probably should have mentioned. It's an auto, and was in "park" on the MOT ramps. I appreciated from the VCU forward the propshaft wouldn't spin due the the transmission being locked (or at least I hope that's the case!) but from the VCU back I was expecting it to spin merrily away.

WRT tyre scrubbing, I notice this when turning round on our gravel driveway on full lock, which again I think is normal. There's no scrubbing on tarmac, although it does need a few more revs (remember it's an auto so this effect might be magnified) at full lock maneuvering on tarmac.

Thanks again...really useful info.
 
My my auto quite happily pulls itself at full lock at idle. If applying lock at idle is stopping it moving?. The VCU is to stiff, so should be removed before damage is done.
 
The Freelander 1 transmission connects/turns like this:

Hippo said:
With the engine oft, chock the rear wheels and put the handbrake on, disconnect the front prop from the IRD and:

With the auto in park (in gear for manuals) lift 1 front wheel and it won't turn. The IRD pinion won't turn when you turn the lifted front wheel. If you put the auto into neutral (neutral on manuals too) the lifted front wheel will now turn and so will the pinion if you turn the lifted front wheel.

If you put the lifted front wheel on the ground and lift the other front wheel the same will happen as above.

If you lift both front wheels and turn 1 the other will turn regardless of the auto being in neutral or park (neutral or in gear for manuals) in the opposite direction. The only difference is the pinion gear will turn if the gearbox is in neutral (doesn't matter if auto or manual). If you sharply turn or quickly slow down the wheel yer turning the pinion will turn more than the wheel yer turning. I assume it's due to the path of least resistance as the power escapes.

If lifting both front and rear wheels on the same side of the Freelander, with the prop/vcu connected, and the engine oft and the auto in park (in gear for manuals) the front wheel won't turn when you turn the rear wheel (assuming the vcu and rear diff work correctly as they should). The rear lifted wheel will only turn slightly which is down to the internal opposition of the vcu. If you do the same test with the auto in neutral (neutral for manuals too) the front wheel will turn in the same direction as the rear wheel.

Note: when I say won't turn, it will turn but only approx 1 inch circumference or a few degrees, as opposed to turning round fully. This is the movement between the gear teeth only.
Click to expand...
 
Nodge68 said:
My my auto quite happily pulls itself at full lock at idle. If applying lock at idle is stopping it moving?. The VCU is to stiff, so should be removed before damage is done.
Click to expand...

I don't think it stops it at idle, but certainly slows it. I'll have a check this week.
 
Hard-Drive said:
I don't think it stops it at idle, but certainly slows it. I'll have a check this week.
Click to expand...
Do the one wheel up test (OWUT). The test is on YouTube done by Hippo.
Most of us use a 1.2M lever with a 5Kg weight on the end. Any time longer than a minute will show the VCU is past its best.
 
I'm so confused about the VCU post because I've recently put a post on about this issue and been recommended I do this test and also contacting Bells Engineering.
If you go on their website they basically say the OWUT is a waste of time?

I was going to do it tomorrow but is it worth it?
 
Giantdog said:
I'm so confused about the VCU post because I've recently put a post on about this issue and been recommended I do this test and also contacting Bells Engineering.
If you go on their website they basically say the OWUT is a waste of time?

I was going to do it tomorrow but is it worth it?
Click to expand...
They do NOT say that.

They say that jacking up 1 wheel and trying to turn it by hand is a waste of time - which it is.

They recommend turning on lock which you have done - and going by that, your VCU is broken beyond belief - which it almost certainly is.

I believe they recommend this test because anyone can do it. Most people on here do not believe it to be the most accurate test though - that is the OWUT.

The OWUT is not discussed on Bell's website
 
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