jamesmartin
Well-Known Member
it seems to have been the right decision ,whereas the vcu can be seen as a weakness it isnt hard to change and freelander was a big success for land rover
GrumpyGel
Well-Known Member
I agree - the main problem with the VCU is people not knowing about its need for replacing and importance of matching tyres. If you own a Freelander and are on LZ (or similar) then you should never suffer transmission failure due to problems relating to the VCU - but its a recipe for problems with people who don't know about the importance of it and the garages where they have the car serviced/maintained also not knowing.
Madmustang
Well-Known Member
How did you do that if I may ask?
blue beasty
Leaks an prone to bits dropping off
Yes but many aren't as sensitive as a Hippo.
In normal conditions the centre diff on a Disco /Fender will take out the difference and assuming diff lock is only used in low traction conditions a little tyre skip prevents transmission windup.
There are of course limitations, wildly different rolling diameters are going to make the diffs work harder.
With either of those in diff lock, not a lot of problems if going in a straight line to get out of trouble. Then knocking it off. But large steering inputs will cause windup. That is why the reverse test on full lock on Freelanders should give an indication of VCU state. IF you know how to recognise it. Because doing that causes all the wheels to travel at different speeds, as they are all describing a different arch.
Madmustang
Well-Known Member
Thanks
Alibro
Well-Known Member
I will probably be doing another one soon so hoping to learn from mistakes doing last one. Biggest one I think was putting fluid in before welding it together. I did it because I wasn't sure how easily it would go in and wanted to see it had got between the plates, with hindsite it was pretty stupid and made it difficult to weld as I had to keep it vertical instead of on its side and I was constantly concerned about the temperature.
Nodge68
Well-Known Member
Wow I missed a huge amount of willy waving on this thread before Christmas.
There are a couple of things that I believe to be inaccurate.
This is inaccurate as the gear ratio between front and rear gives the opposite effect. So when driving straight on the road, the rear propshaft is in fact turning slightly faster than the front. This forces the VCU to slip constantly, trying to make the front prop turn faster. This is the reason why the least worn tyres go on the back. If smaller radius tyres go on the back the rear prop will turn fast still, effectively stiffening the VCU, causing a kind of reverse wind up effect.
Secondly Wammers said that on the road 95% of the drive is going through the front wheels. This again isn't correct as the gear ratio difference between front and rear causes the rear to drag against the VCU. This means if normal straight road driving, is done 100% of the drive by the front wheels. This gives the Freelander a front wheel drive feel but with the benefit of added rear wheel drive when needed.
Wammers also said earlier in the thread that the VCU should be regarded as a consumable item. I believe this to be a sensible statement which is odd because I don't believe much of what he says. LR as far as I can tell never gave the VCU a service life or change interval but as we know, they do go wrong.
A few pages back, a new and probably departed member said something about making sure that the car was serviced and well looked after, then a good VCU is likely. This isn't an accurate view to take. How does anyone know that the well looked after Freelander hasn't been driving with odd tyres or incorrectly had new tyres put on the front. Simple answer is you don't. It's in the owners handbook about tyre purchase and fitment, but who bothers to read that? It's that kind of complacency that causes the early demise of the VCU, IRD and diff.
There are a couple of things that I believe to be inaccurate.
First Wammers said the front prop is turning at a faster rate than the rear.
This is inaccurate as the gear ratio between front and rear gives the opposite effect. So when driving straight on the road, the rear propshaft is in fact turning slightly faster than the front. This forces the VCU to slip constantly, trying to make the front prop turn faster. This is the reason why the least worn tyres go on the back. If smaller radius tyres go on the back the rear prop will turn fast still, effectively stiffening the VCU, causing a kind of reverse wind up effect.
Secondly Wammers said that on the road 95% of the drive is going through the front wheels. This again isn't correct as the gear ratio difference between front and rear causes the rear to drag against the VCU. This means if normal straight road driving, is done 100% of the drive by the front wheels. This gives the Freelander a front wheel drive feel but with the benefit of added rear wheel drive when needed.
Wammers also said earlier in the thread that the VCU should be regarded as a consumable item. I believe this to be a sensible statement which is odd because I don't believe much of what he says. LR as far as I can tell never gave the VCU a service life or change interval but as we know, they do go wrong.
A few pages back, a new and probably departed member said something about making sure that the car was serviced and well looked after, then a good VCU is likely. This isn't an accurate view to take. How does anyone know that the well looked after Freelander hasn't been driving with odd tyres or incorrectly had new tyres put on the front. Simple answer is you don't. It's in the owners handbook about tyre purchase and fitment, but who bothers to read that? It's that kind of complacency that causes the early demise of the VCU, IRD and diff.
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Nodge68
Well-Known Member
It depends on the drive train fitted. My wife has just got a new Ford Kuga. This clearly states in the handbook that the tread depth difference between front and rear must be within 5mm and suggests rotating the tyres every 5000 miles to keep them as close to each other as possible. It also says that the tyres should be replaced as a full set of identical tyres. If this isn't done, transmission damage will result that isn't covered by the warranty.
The D3 should also have tyres that are all the same, much like the Ford. So it's not just the Freelander that has tyre fussiness.
davidsmith1307
Well-Known Member
When I bought the V6 the garage said they had been looking after it for years, and whenever it needed tyres they were sure to put the new ones on the front like they should.
They were mighty surprised when I showed them the handbook.
Nodge68
Well-Known Member
Not uncommon TBH. When I was looking for a Freelander recently, I saw loads that had nice new tyres on the front and part worn tyres on the back. People simply do understand the importance of correct tyre placements.
Alibro
Well-Known Member
Most folk aren't aware of the tyre issues with 4wd cars and probably wouldn't believe you if you said it mattered. They just replace the most worn tyres first and since 99% of tyre depot workers are equally ignorant most Freelanders will end up with new tyres on the front.
Apparently this is correct and the rear prop is driven by the rear wheels 0.8% faster than the front prop. This is to keep the VCU primed so that drive to the rear wheels is more or less instantaneous if the front wheels lose traction. It also means there is no drive whatsoever to the rear wheels in normal use and the car is to all intents and purposes a front wheel drive vehicle until the front end loses traction. I am still waiting for an explanation as to how the MAF sensor controls fuelling on the TD4 by airflow through it, obviously other than by readings from the IAT sensor.
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Nodge68
Well-Known Member
Today I actually got time to test the VCU in my 05 TD4 SE auto. The vehicle has done 111K miles so I'm expecting to need to referbish it.
The time on the one wheel up test was 45 to 50 seconds with a 1.2 meter lever and 5Ks hung on the end.
So I don't think it's to bad just yet but I'll referbish it in the summer and give the results here.
The time on the one wheel up test was 45 to 50 seconds with a 1.2 meter lever and 5Ks hung on the end.
So I don't think it's to bad just yet but I'll referbish it in the summer and give the results here.
Alibro
Well-Known Member
My second Freelander took 2 minutes to do the test so I figured it needed done pronto. The first one was so tight I couldn't move it at all so at 1 minute yours still has some life left.
Nodge68
Well-Known Member
I'm going to rebuild the VCU later in the year. I'm going to try doing this without cutting it open. I plan on using a similar technique to that used for the VW synchro VCU.
Alibro
Well-Known Member
I thought the VW syncro had a removable cap so that it can be taken off for refurbing. Am I wrong?
Nodge68
Well-Known Member
The VW Synchro VCU has 2 screw in plugs at 180° spacing which I assumed was allow the fluid to be changed. However on more research I found that the end cap can be unscrewed for maintenance. The 2 screw caps are in fact, a cast in lump and 180° round a brake type bleed nipple for filling and venting.
I'm going to make my own plugs and fill using a grease nipple. Hopefully pumping new fluid in will force the old fluid out. I'm thinking of orientating the fill at the top, hopefully allowing the old fluid out the bottom.
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