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VCU Viscous Coupling Readings TD4 Manual MY2001

Lovel

Lovel

Accelerating Away
After trawling through endless threads on various sites and finding not a lot tbh but argument after argument. I thought I would post these facts.

BTW, the viscous coupling was the original factory fit in 2001.

With one rear wheel jacked up of the ground. a torque wrench, 32mm socket, and the wheel just turning:

75,000 miles reading of 60ft/lbs, a friends TD4 also tested at the same time gave me the same reading.

Recently the car has been exhibiting creaking and/or thumping noises from the back end with full steering lock, and ruling out all the usual suspects which I know have been fixed or are not applicable. I carried out another test to establish the torque reading this time at 93,000 miles I got somewhere between 80-90ft/lbs.

I decided rather than wait for drive train destruction to occur to replace with a brand new genuine GKN VCU and bearings, the reading with the new VCU fitted is now 60ft/lbs.

The creaking thumping seems to have gone, so looking good hopefully.

I also put a torque wrench across the old VCU on the workbench. A 15/16" (24mm) A/F socket fits the splines tightly, so was able to check torque reading here too. I got 40ft/lbs at the VCU directly, which suggest you lose about 40-50ft/lbs reading when you take it at the back wheel.

Well that's my lot for now. :)
 
Hippo said:
What type of torque wrench were you using, and did you apply the pressure to it yourself?
Click to expand...

Applied by hand, just enough to begin to turn the wheel using this item. Some folks will no doubt say that this type or wrench is not accurate enough. I dont really care, it is the relative difference between VCU's I was looking for to give me a trend.

torque-wrench.jpg
 
Thanks for the info.

The best test I know of is one which puts a known weight on a length of bar, which allows you to calculate the force/effort in Newton Meters, as the bar turns, whilst timing the time it takes for the bar to turn 45 degrees from angle A to angle B. Sounds a bit complex, but easy to do on a diy basis at home.

I would agree we all have differing opinions on which test is best. But as you say, your test before and after the vcu replacement has proved the change has benefited your Freelander, and was the right thing to do. That's the main thing.
 
I have been having problems with my 2001 td4 , it does not want to move on full lock unless you give it some gas . i have asked various people ranging from forums to a landrover main dealer and a firm called bells engineering on the best way to test if the vcu is faulty . The dealer said they had not experienced any vcu failings so they did not know how to test ( i suspect this is because they fail out of the warranty period and noone wants to pay main dealer labour charges).Some forums say jack up the rear wheel and turn the rear prop with a bar in the joint. Bells said put the car in reverse and full lock then drive backwards in a circle then put your foot on the clutch and if it feels as though the handbrake is being applied then the unit has failed.I have also read where people have experienced this problem and replaced the unit only for the symptons to still be there.
 
Try the one wheel up test. Chock the front wheels, hand brake off, and lift one wheel. Put a 32mm socket and bar on the big nut, and a known weight on the end. This gives you an idea of the slippage available on your vcu. It's not perfect, but it's an indication which a diy'er can do at home, without taking the vcu off the car.

http://www.youtube.com/watch?v=Oh01nQgh7z8
 
With Hippo's test, the bar needs to about a metre long, and it should move smoothly but very slowly with a fair pressure on it. I have always recommended this method. I am doubtful of Bell Eng's method. Some inbuilt stiffness is normal.

If it is jerky or impossible to move then take the whole prop and VCU off until you can replace it. To continue driving risks causing VERY expensive damage.
 
Yep. We started to time it turning to look for comparisons. The effort put on the bar is:

9.8 (gravitational acceleration) x bar length x weight = Nm

We timed the bar turning 45 degrees. You have to take up the slack in the transmission, and start turning the prop before timing, to get a fair test. Hence starting at the black blob, and timing through the thick red line in the pic below. The is because the weight is greater when the bar is horizontal, as opposed to verticle. This was done on lz to try to create a rule of thumb. Not perfect, but again something to use as a comparison. We have an example test of a good, bad, and average vcu coming soon.

WheelTorqueGraph.jpg
 
just finished timing how long it takes to complete 45 degrees as per your diagram , used a 1.2 m bar on the centre nut with 8kg of weight connected to the other end and over 10 runs the average was 53.2 seconds.seemed to take an awfull lot longer than the ones on you tube ,as i have no comparison does this indicate a seizing vcu or one that is about to ?
 
Just watched your video on you tube Hippo and using crude measurements it seemed to only take your bar 10 or so seconds to go from 45 to 90 degrees .That doesnt look good for mine .
 
The problem is there is no "standard" for this, so just because your's took longer doesn't have to mean it is fubbared. I found it had more to do with the feel of the movement.
 
So it seems as if it is one of those results that come down to personal interpretation ,the speed at which it turned seemed to remain smooth . Can i take it that because it turned, all be it painfully slowly , then the vcu is not seized ?
 
If it was seized you wouldn't move it AT ALL!!

Too many people panic because they hear all the stories and think it applies to them, when in fact it doesn't. I suggest you go out and enjoy your car and use it for what it was built for, gentlish off-roading.
 
The general idea behind this test was to create a rule of thumb, for owners to use as an example. Sadly we didn't get enough people to do the same test. There was also a troll arguing in the middle of this... Hence results are limited. We were hoping to be able to compare age of vcu, mileage travelled, and if it was known to be the original or not. We had some offers from those who bought new replacements etc who said they would put up results, but few did. the test isn't proof, and many have knocked it... but we don't have a definitive test to be able to measure the sheering effect of the silicon in the vcu, that owners could do at home on a diy basis, as a guide to the health of their vcu. Would be nice to be able to state that above a certain time frame, the vcu is on it's way out. I think I'm right in saying the ratio's in the rear diff may alter between models, so this will offset results a little. The video has gone global, across numerous countries, so hopefully we will find someone who'll sus it out. If peep on ere want to do the test and put up results, or pm them to me, I'll add them to the list and report back one day.
 
(missed the edit window!)

As I have said previously, Land Rover and others do not provide an exact torque measurement for the VCU, presumably because there are too many variables. Whilst I agree that your test gives an indication of the VCU condition, it cannot be considered a "standard" until many brand new units are tested comparitively using a known standard technique, under controlled conditions.
 
well i had my unit looked at by 2 independant landrover garages today , first one put it on their ramp , jacked up the wheels , then put a screwdriver in the uj on the prop either side of the unit , he pushed one and pulled the other but nothing moved , their conclusion , the unit is seized.
second garage did nearly the same except they used longer prise bars instead and the front one was held against the underside of the car while the rear one was pulled in the opposit direction,you guessed it the unit turned very slowly .I then got them to mark the items on the unit that should move , and took it for a spin round a nearby car park , doing figure of eight and left and right circles, took it back to the garage and the marks were no longer in line , which they said showed that the unit is working.
 
Llanigraham said:
I see no troll in this thread, only people with practical experience of Freelander's.
Click to expand...
Troll was on a different forum, not this one.

Would agree about comparing figures against new vcu's. But not many people have posted results, although many have promised across several forums. the more figure we collect the better.
 
i little off topic but on my wifes newly acquired freelander 2001 td4 when reversing on full lock it will not free wheel is this a seized vcu? if you take it off full lock slightly then all is fine.
 
Hi mudskipper, these symptons are the reason i had mine checked out , especially after reading on the bell engineering site that this is how they say to check the vcu, but after getting the check done by the second garage they said it is normal.
It feels awfull doesnt it ! I think i might take teh front and rear prop off with the vcu and just replace them when the weather turns nasty.
 
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