Noisy vcu

Hi,
I have a problem with my freelander td4 04plate.
When I go round right hand tight corners in 2nd gear at about 15mph there is a juddering/clonking noise coming from the vcu.
I know that there can be issues with these and have also read that you can have strange noises etc in the drive chain while turning full lock.
Just wanted some advice whether to get a new one or not?? Thanks.

Usually the support bearings either side of the VCU, front one usually goes due to ingress of dirt.

Seek out and "perform one wheel up"test to see if you need vcu and its support bearings, or just new bearings

I bought it about 6months ago and have a receipt for 2 bearings that were fitted about 18 months ago so I presume they should be okay?
How do I perform the one wheel test??
I must add that this is the only thing that worries me the vehicle drives perfectly well apart from the occasional noise when turning right.

It could be the support bearings - but it could just as easily be the rear diff (mounts) - noise travels through the transmission and chassis and doesn't always sound like its coming from where it originated.

I've never had either go, so have no first hand experience, but from threads on the forum I believe when the support bearings go, they usually groan all the time - its more usual that its the mounts for the rear diff when the noises are clonking and on cornering.

You are probably in for a replacement VCU - as said do the 1WUT with a 1.2M bar and 5KG weight and hope for a time under 1 minute - over 2 minutes is a definite replacement. Also though, check that all your 4 road tyres are pumped to the same pressure - and I assume you are running 4 identical (make & model) tyres. These all affect whether a Freelander's transmission works or destroys itself. If your tyres are all OK - do you get a braking/binding effect on the car when your reverse around a corner on full lock? If so this is another indication that the VCU has gone to tight.

Dan H said:

I bought it about 6months ago and have a receipt for 2 bearings that were fitted about 18 months ago so I presume they should be okay?
How do I perform the one wheel test??
I must add that this is the only thing that worries me the vehicle drives perfectly well apart from the occasional noise when turning right.

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Where did the bearings and VCU come from? What make are the bearings? Is the VCU a new GKN unit, a recon or from a breakers?

Original LR/GKN bearings should last a long time, cheap replacements (eg bought to sell the car!) can last anything from about 2 miles upwards! Even LR/GKN ones though can go quickly if they were not installed (alligned) correctly.

A VCU from a breakers is a gamble - especially if its not tested properly. There are plenty of cowboy outfits that will supply a "recon" VCU - most are dangerously pulling the wrong viscosity. Needs to have come from a good supplier.

As far as I know it was just the bearings that were replaced not sure what make.
I will do the test when I get time and let you know the outcome thanks.

Cheap bearings are well known to fail quickly and I suspect a stiff VCU will cause them to fail even quicker along with the front diff mount (on the rear axle) If it were me I'd be checking the VCU as a matter of urgency and if in doubt whip the propshaft off.

Dan H said:

As far as I know it was just the bearings that were replaced not sure what make.
I will do the test when I get time and let you know the outcome thanks.

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If you are not going to do the 1WUT very soon - I would consider removing the propshafts & VCU. oops Alibro beat me...

Alibro said:

Cheap bearings are well known to fail quickly and I suspect a stiff VCU will cause them to fail even quicker along with the front diff mount (on the rear axle) If it were me I'd be checking the VCU as a matter of urgency and if in doubt whip the propshaft off.

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If the VCU is to tight or (even worse) the tyres do not match or are not pumped to the same pressure, it may not take long for the transmission to destroy itself. You have good warming signs to be worried.

If you do need a replacement VCU - heed the warning above! Either get a new GKN one or a recon from someone other people recommend - such as Bell Engineering.

Dan H said:

I bought it about 6months ago and have a receipt for 2 bearings that were fitted about 18 months ago so I presume they should be okay?
How do I perform the one wheel test??
I must add that this is the only thing that worries me the vehicle drives perfectly well apart from the occasional noise when turning right.

Click to expand...

If it is the VCU bearings it will be the same whichever way you are turning.

Its far more common for the bearings to go than the VCU by the way, although people with skin in the game will tell you otherwise.

The one wheel test is to jack up a rear wheel and see how much torque it takes to turn it. If its solid (brakes off of course) new VCU time. It can be pretty stiff and still be OK.

If you crawl under he car crapped out bearings that move in the rubbers are easy to ID - just wobble em a bit.

Checked the bearings and they look fine to me.checked tyre pressure and two were a bit low so topped them up.
Drove it on the corner where the knocking occurs and didn't knock however it doesn't always anyway.
Will carry out the 1wut tomorrow and see what happens. Thanks for all the help so far.

This does not IMO appear to be a vcu related 'noise' issue . - most likely CV but also consider IRD issues,
Check - as a matter of urgency, the rh inner cv joint - and of course the outers. It is strange that you say are getting noise only when turning right - so it appears
Your problem could well be the IRD - not simply the VCU. - of course, it could also be something much less serious like a CV joint.
Can you feel anything through the steering when it 'knocks' ?

Drive the car in reverse on full lock in both directions - slowly, also forwards on full lock and see if you get any unusual noises or knocking or feeling as if the brakes are being slightly applied at full lock. The OWUT is also viable however you need to identify where the noise is coming from immediately , if it IS the ird the damage is done.

What makes you say it is 'coming from the VCU' ?

'clonking' as you put it, especially on lock, in a 'normal' fwd vehicle is indicative of cv joint issues. On a freelander, it is also thus, BUT, also potentially indicative of IRD failure. There should be no play at all in the cv joints. The rh inner - where it enters the IRD can cause catastrophic failure of the IRD if there is excessive movement in the CV.
IF it is the IRD, (and let us hope it is something else and much simpler and cheaper - like a cv joint ) - then as said the damage is done.

If you think the noise is coming from the middle of the car underneath when on full lock then it is probably coming from the IRD input pinion to crownwheel (another type of ird failure - if ird it is usually the input pinion to crown wheel teeth - or, the rh inner cv area where the main concentric shaft / diff unit pass drive to the output shaft in the ird), unlikely to be the VCU at all (making the noise) - the VCU may well be captain cooked though.

Can you feel anything through the steering when it 'knocks' ?

Just to add, if you have pumped up the tyres and the sound is less then it is unlikely to be either a CV or the VCU.................

Can't feel anything through the steering wheel and the noise which would be better described as a creaking doesn't happen all the time and from inside the car it sounds like it's coming from just behind the gear stick and this is approximately where the vcu is.

Hmm, a creaking isn't a juddering or clonking.
If you can't feel anything through the steering that is very good news.
It is often extremely difficult to identify where a particular noise is coming from but at least from your latest description it does not sound too problematic. Still do the full lock forward and reverse - both left and right as described above and check for ANY unusual noises or knocking or feeling of brakes being applied. Also do the OWUT as you said you are going to do.
When doing the forward and reverse on full lock to check for noise etc - make sure it IS full lock.
IF it was anything to do with vcu it would occur on both left and right as the vcu has to turn slightly to compensate for the differing front to rear axle speed and otherwise always lies in the same plane.

Thanks for the advice, I will do as you suggest and I will let you know the outcome.

Tyres being at different pressures is bad news when driving in a straight line - because the axles will be turning at different speeds - which tells the VCU that 1 axle is slipping. So if the "slippage" is enough it will "lock up" the transmission - which will destroy the transmission.

When the car is turning, the outer wheels of the turn travel further than the inner and the front axle travels further than the back - once again further and less travel creates a scenario that tells the VCU an axle is slipping. With tyres pumped to different pressures, there is a high likelyhood that the amount of "slipping" the VCU sees will be different when turning left or right. So just making sure all your tyres are at the same pressure may have solved your problem.

However, it may also just mask the fact the the VCU has gone stiff. So you should still carry out the tests - including the ones not related to the VCU in case it is not related to that.

If it is a creaking, you should also do a search on here for "cracked chassis", for example https://www.landyzone.co.uk/land-rover/cracked-chassis-repair-no-welding.243704/

My penny-worth. Clonking from the region of the VCU could be as simple as the VCU & its support bearings not being aligned or a worn centre diff' mount, or even a worn lower engine tie bar.
For the first on you can simple check the measurements from the front and rear VCU faces to their respective support bearings. Left and right sides should be the same but the front measurements may be different to the rear measurements that's okay. It's true that cheap bearing won't last long. When I changed my VCU and bearings I had a knocking. I checked the alignment and I hadn't got it right. However it was easily sorted. I could see on the bearing's rubber where it had been flexing as it was dust free on the outer edges while the rest had its coating of dust...
The centre diff' mount will look tired or could even be disintegrating.
The lower engine tie bar bush could be shot - use a bar and see if you can lever the motor fwd... Bk.. That would knock when you change gear...

The one wheel up test [OWT] gives an indication of the VCU's condition and is a good thing to do. Timing the weighted bar's movement from 45º to horizontal should Ideally be about 30 seconds which would be very good = VCU fine, getting close to two minutes and it's time to replace it.

Done the test as suggested the wheel was quite stiff but did move (not as quickly as I had hoped).
Drove at different speeds forward and reverse in full lock no noises whatsoever.
Hasn't made the noise as yet while cornering Could it be the fact that the tyre pressures were slightly different? Is it that crucial??

Dan H said:

Done the test as suggested the wheel was quite stiff but did move (not as quickly as I had hoped).
Drove at different speeds forward and reverse in full lock no noises whatsoever.
Hasn't made the noise as yet while cornering Could it be the fact that the tyre pressures were slightly different? Is it that crucial??

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Did you do the OWUT with a 1.2 Metre lever and 5 Kg weight? If so what time did you record for the lever to move from 45° to 90°? Less than a minute ideal. Over a minute means a VCU will be needed soon. Over two minutes means, remove propshafts until a new VCU can be obtained.
The tyre pressure is important, but 1 or 2 PSI won't make a huge difference, for a few miles.
The same make, type and size of the tyres is more important than a couple of PSI of pressure difference.

Owut took about 80 secs.
All tyres are identical I will look into getting a brand new vcu and bearings.
I can get one with bearings for about £400 and I've been quoted £120 labour.