Returning to 4WD after VCU removal

I've had my TD4 auto for about three years and after about a year or so I noticed my VCU was tightening up. So as a precaution I whipped off the VCU and prop shafts whilst I saved up for a new one. The time is now approaching to return the car to 4WD. I've run it for the best part of two years (25k give or take) in mondo mode. Now I've no reason to suspect the diff or IRD have suffered as I'm pretty confident I caught it in time. However, I was wondering if there is a prudent/precautionary checklist of things that could/should be carried out before refitting the new VCU just to make sure?

Changing the fluids in the diff and ird wouldn't do any harm

pardec said:

Changing the fluids in the diff and ird wouldn't do any harm

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This^^^^
Additionally. Examination of the removed fluids will give you a good idea of the condition of the components inside.
Dark coloured oil is fine. If there's a silvery or metallic tinge, then wear has taken place. If this is the case, a rebuild of that unit is necessary.

Also make sure you get original GKN carrier bearings or you will be replacing sooner than you want

kernowsvenski said:

I've had my TD4 auto for about three years and after about a year or so I noticed my VCU was tightening up. So as a precaution I whipped off the VCU and prop shafts whilst I saved up for a new one. The time is now approaching to return the car to 4WD. I've run it for the best part of two years (25k give or take) in mondo mode. Now I've no reason to suspect the diff or IRD have suffered as I'm pretty confident I caught it in time. However, I was wondering if there is a prudent/precautionary checklist of things that could/should be carried out before refitting the new VCU just to make sure?

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Things that suffer from stiff VCU:
1. Rear diff - check for noise, play, oil leaks.
2. Rear diff mounts
3. Prop carrier bearings - fit decent ones. Avoid Britpart/Allmakes.
4. IRD - warm it up, change oil. Check for lots of metallic debris and check pinion play.

Following on from the above, if the IRD oil comes out metalicy you can get bearing kits for about £150 - it depends on how good/confident you are at fitting them as to how much the ultimate cost will be. More to the point though is any wear in the gears. Before you go splashing out on a bearing kit, which may be worth while even if you stay with 2WD, you'll also need to see if there has been any damage to the crown and pinion gears as they are a lot more money.

Hopefully it will come out nice and dark

I picked up a Freelander that had a 3 minute 1 wheel up test time when I first did it. I ran the test a few times and it settled at just over 2 minutes - still way over what you'd be happy to run the car at. When I checked the oil it was nice and dark - so hopefully its OK, although I don't know if the oil had been changed and how recently.

What's this "1wheel up test" all about?

Its test 3 on the following...

https://www.landyzone.co.uk/land-rover/tests-new-freelander-owners-should-do-on-their-car.312863/

On LZ "the recommendation" is to use a 1.2M bar and 5KG weight and take the time from 45 degrees to horizontal - this way we can get as many timings as possible to get a more accurate reading. You can see people's results, together with a load of normal off-topic spats on...

https://www.landyzone.co.uk/land-rover/vcu-torque-test-results.109486/

So, all the sensible checks done by a transmission specialist. IRD and diff oils changed. Both looked good when they came out. Nice and dark, no evidence of metal. No signs of play or wear. Diff supports are all good. As a result, a Bell recon VCU + new bearings (also supplied by Bell) are going on. Are there any ways that I can balls up the refitting of the prop? Is it easy to get the VCU bearings lined up? I'm excited to be getting the car back to how it should be but don't want to fall at the last hurdle.

Also, is it worth doing the OWUT straight away for reference? I will be meticulous with tyre maintenance but are there any recommendations on how often to do the test once fitted, and any idea what life the Bell recon unit is likely to have?

EDIT - 4 new tyres fitted the other day btw.

The VCU mounts can be installed wrongly - or at least imperfectly. The rear diff pinion and the IRD pinions are offset from each other a bit - but I believe the VCU must be mounted 'straight'. I believe @Alibro has commented on this in the past.

When I removed my props, I made sure that the bearings covered the marks left by the old ones. Its been running fine without grumbles from the bearings, UJs or CV for 4 years - however, I reinstalled the same VCU/supports and removed the drive from the IRD so probably not the best example!

GrumpyGel said:

The VCU mounts can be installed wrongly - or at least imperfectly. The rear diff pinion and the IRD pinions are offset from each other a bit - but I believe the VCU must be mounted 'straight'. I believe @Alibro has commented on this in the past.

When I removed my props, I made sure that the bearings covered the marks left by the old ones. Its been running fine without grumbles from the bearings, UJs or CV for 4 years - however, I reinstalled the same VCU/supports and removed the drive from the IRD so probably not the best example!

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As GG said I suspect quite a few VCU support bearings fail prematurely due to incorrect fitting. If they're not dead square to the VCU then the rubber supports will be stressed, the bends in the propshaft need to be at the CV joints.
The first time I did the job I had the CV joint almost dead straight with the support bearing twisted slightly but later after thinking about it I refitted and all was well.

As above.
You can always pop over to mine for a hand, if you get stuck.

Just reading that (thanks @guineafowl21 ), I did mark the flanges when I removed the prop, BUT i'm expecting the marks to be long gone now. Is it critical that the prop goes back bolted to the exact same fixing holes as it came off?

P.s. @Nodge68 I might be in touch, but I'm hoping to have it all sorted without pestering anyone.

kernowsvenski said:

Just reading that (thanks @guineafowl21 ), I did mark the flanges when I removed the prop, BUT i'm expecting the marks to be long gone now. Is it critical that the prop goes back bolted to the exact same fixing holes as it came off?

P.s. @Nodge68 I might be in touch, but I'm hoping to have it all sorted without pestering anyone.

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its not critical or even necessary to mark prop flanges so as they go back in the same holes, it makes no difference, how would you fit another prop to a vehicle using the same holes

jamesmartin said:

its not critical or even necessary to mark prop flanges so as they go back in the same holes, it makes no difference, how would you fit another prop to a vehicle using the same holes

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That's what I was expecting/hoping. Just wasn't sure given that there are balancing weights on the prop. Didn't want to throw anything out of kilter.

kernowsvenski said:

That's what I was expecting/hoping. Just wasn't sure given that there are balancing weights on the prop. Didn't want to throw anything out of kilter.

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they are for the prop which is balanced when made not on a car ,but even then i see lots of props were the weights have rotted off and no one can tell the difference