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Viscous test with a bar and weight.


gadget

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I've searched and read a bundle of posts on here regarding VCUs and their deaths.

One post had a link to a thread on lz that suggests a 1.2M bar and a 5kg weight and timing the drop of the weight.

Bell engineering site seems to suggest that youd need a large bar and some grunt to turn the wheel.

Bell also suggests that the tippex test isn't indicative either.

The one on swmbo's freelander will turn with a bar and weight, but extraordinarily slowly.

The first test would suggest that the VCU is kaput, but it fits with Bell's thoughts.

Brakes aren't sticking or binding so can attribute all of the required force to the VCU.

I've not had a chance to take the VCU and props off yet so don't know how it behaves when off the car.

I would have thought that VVVF-stiff = not good?

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When I fitted my reconditioned VCU from Bell, I did the test on it and with a 1m bar I was able to turn the back wheel slowly by pushing down with reasonable force. I don't know what that equates to in terms of weight, but quite a lot I should think!

Unfortunately, I hadn't tried this test before with the knackered VCU, but the symptoms were obvious - back wheels 'skipping' when going round tight bends at low speeds in Tesco's car park.

I don't think the white paint test would prove much either.

After fitting the reconditioned unit, the 'skipping' had completely disappeared. The drive train still felt tight on full lock (e.g. reversing into a parking space) but this is normal, I believe.

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I've tried just turning the wheel with both a knackered and new VCU. I couldn't turn the wheel with the knackered one at all, even using a long bar. With the new one, I could turn the wheel slowly.

The thing about any viscose coupling is it should move slowly with little force. To get it to move quickly, the force increases exponentially. Imagine moving your hand through treacle. If you move it very slowly, it will encounter almost no resistance as the treacle has time to move around your hand. Moving it faster, it does not have time to flow, so you are moving a big bow wave in front of your hand.

My experience was at the two extremes of working and solid. Because there is a sliding scale between the two, it's hard to call when it can be considered knackered. I would say it's knackered when the car starts misbehaving.

Si

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At present i don't know if the car is behaving or not. First freelander and nothing so compare it to.

I'll drag it off to a car park and see if the wheels skip.

Will it show skip in both directions at full lock? More importantly, will the skip be obvious to the untrained observer?

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Never heard skipping as a diagnostic. Dragging (as if the handbrake's been left on) when manoeuvring / parking (full lock) is an indication, and lots of clonking/groaning from suspension when doing so, as is scrubbing rear tyres, but as Bell's website says it's very hard to diagnose with any degree of certainty.

It will always have some drag, that's how it works, and it's very temperature dependent too - when cold it's much freer, we were down in Bosnia in 40degC+ heat and it was quite a job to park the thing as it would lock solid when you tried to manoeuvre!

The VCU's have a rated service life of 70,000 miles, so that's one indication.

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FF: The reason i'm interested in trying to determine if the VCU is duff is that it has higher mileage than yours and there is no info in the documentation that came with it that is has ever been replaced :o

If yours is over 100k, 10+ years old etc. and you're planning on keeping it, £250 is the price of peace of mind.

Bear in mind, driving with a seized VCU will be lunching the rear diff and the IRD, stressing the suspension, eating tyres and burning more fuel.

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I tried to post this last night but something was duff in lr4x4-land.

---

After doing the slowest doughnuts Tesco carpark has seen in a while...

720 degrees forward and reverse, both directions on tickover. No scuffing to report.

An intersting tick noise every 3/4 of a second when going around roundabouts at speed though.

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If yours is over 100k, 10+ years old etc. and you're planning on keeping it, £250 is the price of peace of mind.

It's MUCH closer to 200,000 miles :o I've no problem is replacing the VCU if the one on it is duff.

SWMBO doesn't want to drive it until it has "stopped making those horrible noises" and until then she wont know if she's to keep it or not. I'd like to fix the noises a cheap as possible, but without cutting uneccessry corners.

I think it will boil down to mondo mode. Lots of test drives and then fix the noisy bits. :D

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At 200,000 miles I'd definitely replace the VCU and support bearings. I changed mine at 106,000 and used Bell's at a cost of £280, I now have piece of mind. If you intend to leave in Mondo mode then you should notify your insurer as this is classed as a modification.

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At 200,000 miles I'd definitely replace the VCU and support bearings. I changed mine at 106,000 and used Bell's at a cost of £280, I now have piece of mind.

The piece of mind angle has already crossed my mind, but with such a high mileage car my piece of mind parts swapping could end up being rather pricey in the end.

If the recon is that much i'll probably opt for a new GKN at £360 instead.

If you intend to leave in Mondo mode then you should notify your insurer as this is classed as a modification.

It will be 4wd or sold. A 2wd focus has lower VED and insurance than a 2wd freelander :)

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Props are off and the drone is no more :) Still way more road noise than i expected though.

The rear prop is away from the VCU but no amount of bashing wanted to free the front prop from it.

The cavity between the rear prop and the rear diff flange was full of oil. Is the seal on the pinion nut easy enough to swap?

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Props are off and the drone is no more :) Still way more road noise than i expected though.

The rear prop is away from the VCU but no amount of bashing wanted to free the front prop from it.

The cavity between the rear prop and the rear diff flange was full of oil. Is the seal on the pinion nut easy enough to swap?

If it's droning, it could well be flat spotted tyres, especially if the VCU was knackered. As it scrubbs, it flats spots the rear tyres causing road noise.

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If it's droning, it could well be flat spotted tyres, especially if the VCU was knackered. As it scrubbs, it flats spots the rear tyres causing road noise.

When i've replaced the VCU and put the props back on i'll take it for a test run on a smooth road rather than the country lane i was on and see how it sounds. Hopefully i'll be able to determine what's creating the noise there.

I've still got to get the VCU and front prop apart. I've cut the bearing off and will get the blow lamp on it, and a bigger hammer, when a get a bit of spare time.

Found another fault on it too. The wipers don't park.

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I found that slackening the UJ retaining bolt a bit and then driving a wedge-shaped bit of metal down there works, but can take some hammering if it's proper stuck. The UJ yokes deform easily if you hit them with a lump hammer, and it may not be obvious until you start lunching UJ's regularly...

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I've deformed one of the UJ yolks already using a small ball pein hammer. It's not beyond repair yet.

It's definitely stuck. I spent a long time with hammers, wedges and swearing and it wouldn't shift at all.

Now that the bearing is off i'm hoping that heat + hammer + swearing will be the answer.

I'm considering changing the UJ on this prop because all this hammering can't have done it any good :(

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