VCU Torque test results

It’s not the same test. The “one wheel up test” puts a known force on the vcu.

Force is the most important bit. Without a known reference of force applied, a test would be invalid. Force is key to understanding how the test works.

The “one wheel up test” supplies a time to turn 45 degrees to the horizontal. That means the test turns 45 degrees, and stops at the horizontal. The time taken to do this is measured, as a reference of force applied. The bar should start turning before the test, so it takes up the slack in the transmission and starts to apply the force to the vcu.

The force measurement is the pressure applied by the weight, due to the length of the bar, compared against a fixed reference = gravity. Betterer known at torque. If you hold a 2kg object close to your chest, its weight is a certain amount. If you hold the same 2kg object at arms length, it feels heavier, but the weight is still the same amount. Why? The answer to this is key to why a known force is so important. Torque = force x distance.

The weight of an object changes with distance. Thats why the same 2kg weight feels heavier at arms length. Bit like when you were at school and did balancing. 10kg at 1m balanced perfectly with 2kg at 5m on a sea saw. The “one wheel up test” uses the same principle. A known weight on the end of a bar of known length. The known length is the measurement of the distance between the pivot point (drive shaft wheel nut) to the connection of the weight on the end.

The best way to display the results are to measure torque at a certain point, depending on the angle. That means

Torque = weight x gravitational acceleration x (length of weight to pivot x cos Angle)

For a 1.2m bar and 4kg weight:

Torque = 4 x 9.8 x (1.2 x cos Angle) = torque in Nm

Measuring torque (force applied) is the bet thing to do. Torque against time is even betterer.

Buts it’s too complicated so after much debate we settled for the time to turn 45 degrees to the horizontal, with a known weight and known length of bar (distance from pivot to weight). The torque graph I posted above shows the torque applied verses angle, which is nearly the same during the test of 45 degrees to the horizontal. Hence weight and length factors still count. Cos Angle is taken out as we’re timing in seconds the amount of time it takes to turn.

Physics experts on ere such as young porky will have spotted a fundamental problem with this test. The weight of the bar needs to be taken into account too. The bar applies a varying force as it turns. At 3 o’clock it’s force is greater (maximum) than 2o’colck. We can take out this factor by performing the test several times, each time with a different weight. Subtract one result from the other to give the weight factor only, with no bar weight factor. Hence 6kg result – 2kg result = 4kg only known weight applied.

Sadly this isn’t an option as very few do the test anyway. Why? Not really sure myself. They either can’t be bothered or don’t think it’s worth doing. I appreciate some may feel it’s not something they can do. Some won’t have a big enough socket. Some argue it won’t work. Some argue a better test is appropriate. A common theory of changing the vcu at 70k seems to win most views. Why? Because a number have failed around or above this mileage. Without testing they’re happy to pay for a replacement when they may not need it. Bit like changing all Jatco auto’s at 100k miles as they suffer failures at that mileage.

I can confirm my vcu works ok. Last tested a few weeks ago. I’ve posted my results loads on times on ere, and other forums. Tried to get other forums involved in the testing too. Tested vcu’s on other peeps vehicles anorl. One of which compared nearly the same to mine, and he still changed it. After years of debate (including a few arguments) we still don’t have enough test results. Without that vital input, we’re stuck.

The Mad Hat Man said:

sounds a good simple system, but the usual method involves a known length pole, a known weight and a known angle of displacement (normally 2 Oclock-5Oclock) and the time taken is measured. using a torque wrench has been thought of before, but I think it was discounted. I would like to see Bells comments on this.....


results are here

Click to expand...

torque wrench was borg warners approved method of checking ,even new vary to some extent

Hippo said:

It’s not the same test. The “one wheel up test” puts a known force on the vcu.

Force is the most important bit. Without a known reference of force applied, a test would be invalid. Force is key to understanding how the test works.

The “one wheel up test” supplies a time to turn 45 degrees to the horizontal. That means the test turns 45 degrees, and stops at the horizontal. The time taken to do this is measured, as a reference of force applied. The bar should start turning before the test, so it takes up the slack in the transmission and starts to apply the force to the vcu.

The force measurement is the pressure applied by the weight, due to the length of the bar, compared against a fixed reference = gravity. Betterer known at torque. If you hold a 2kg object close to your chest, its weight is a certain amount. If you hold the same 2kg object at arms length, it feels heavier, but the weight is still the same amount. Why? The answer to this is key to why a known force is so important. Torque = force x distance.

The weight of an object changes with distance. Thats why the same 2kg weight feels heavier at arms length. Bit like when you were at school and did balancing. 10kg at 1m balanced perfectly with 2kg at 5m on a sea saw. The “one wheel up test” uses the same principle. A known weight on the end of a bar of known length. The known length is the measurement of the distance between the pivot point (drive shaft wheel nut) to the connection of the weight on the end.

The best way to display the results are to measure torque at a certain point, depending on the angle. That means

Torque = weight x gravitational acceleration x (length of weight to pivot x cos Angle)

For a 1.2m bar and 4kg weight:

Torque = 4 x 9.8 x (1.2 x cos Angle) = torque in Nm

Measuring torque (force applied) is the bet thing to do. Torque against time is even betterer.

Buts it’s too complicated so after much debate we settled for the time to turn 45 degrees to the horizontal, with a known weight and known length of bar (distance from pivot to weight). The torque graph I posted above shows the torque applied verses angle, which is nearly the same during the test of 45 degrees to the horizontal. Hence weight and length factors still count. Cos Angle is taken out as we’re timing in seconds the amount of time it takes to turn.

Physics experts on ere such as young porky will have spotted a fundamental problem with this test. The weight of the bar needs to be taken into account too. The bar applies a varying force as it turns. At 3 o’clock it’s force is greater (maximum) than 2o’colck. We can take out this factor by performing the test several times, each time with a different weight. Subtract one result from the other to give the weight factor only, with no bar weight factor. Hence 6kg result – 2kg result = 4kg only known weight applied.

Sadly this isn’t an option as very few do the test anyway. Why? Not really sure myself. They either can’t be bothered or don’t think it’s worth doing. I appreciate some may feel it’s not something they can do. Some won’t have a big enough socket. Some argue it won’t work. Some argue a better test is appropriate. A common theory of changing the vcu at 70k seems to win most views. Why? Because a number have failed around or above this mileage. Without testing they’re happy to pay for a replacement when they may not need it. Bit like changing all Jatco auto’s at 100k miles as they suffer failures at that mileage.

I can confirm my vcu works ok. Last tested a few weeks ago. I’ve posted my results loads on times on ere, and other forums. Tried to get other forums involved in the testing too. Tested vcu’s on other peeps vehicles anorl. One of which compared nearly the same to mine, and he still changed it. After years of debate (including a few arguments) we still don’t have enough test results. Without that vital input, we’re stuck.

Click to expand...

a torque wrench does put a known force on ,and regular checking lets you know if its changing for the worse

I tend to agree, James. But as I said before, for some reason it was discounted. I can't remember why.
As Hippoo said, without a number of rests, any test is meaningless.

jamesmartin said:

a torque wrench does put a known force on ,and regular checking lets you know if its changing for the worse

Click to expand...

The torque wrench method is done with a 2 bar torque wrench. If using a normal type that most have, you can make up your own results by applying more or less pressure, with differing click settings. The method above where andy discussed the torque wrench involves fixing the position of the wrench, then turning the wheel, whilst changing the click point so you can work out how much pressure your putting on the wheel. The problem here is you can't measure how much force/pressure your applying to the tyre. Just enough to turn, or just enough to overcome the vcu's effective resistance. The margin is only slight but the results are widely. It's difficult to explain but if you have a go you can get results to vary. The only way to do this would be a rope round the wheel fed through a pulley up high with a knwon weight hanging from the end of the rope, in the air. As the weight lowers due to gravity, the wheel is turned. Then adjust wrench to get the click point. Hence known applied pressure as a datum for reference giving a more reliable result.

your making it over complicated, v/cs vary as of new,just check regular your own and stiffening will show

I currently compare my own results and compare to those to pass me results.

With respect, the whole point of why we’re looking at this in such detail was to create a test the majority could perform. Then pool the results and look for a rough guide. This could relate to things such as age of vcu, mileage or some other unknown factor, which may pop up. There’s is a trend for force applied against time which displays on a graph easily. Finding a test the majority agreed on was difficult enough. Getting people to perform the test is even harder. MHM put up a picture method of how to perform the test. I put up a video of the method on Youtube which has had over 23000 views. Unfortunately the momentum to find a rough guide to the state of a vcu, with comparison to results collected, just hasn’t happened. If it had, Freelander owners could compare their own results with the pooled results and take an educated guess of needing to replace their vcu or not.

Just to close the loop .... Originally posted (on this sticky) a simple test with a simple torque wrench and concluded 35 lb ft for a good VCU and 80 lb ft for a tight one. Measured as shown previously at the rear wheel. Now all of the information about different gear ratios etc and whether it is perfect is all good stuff, but today I got the test results from Bell for my 'old' unit - the one considered tight.

They report that it took twice the time of a good one to complete its required motion when tested off the car.

That is good enough for me (I made it 2.2 x). I conclude that anything over 70 lb ft needs testing - easy test, repeatable, plotable, trend can be seen, everyone has the tool, takes 5 mins to do. More data useful, but that is my rule of thumb. Maybe I was 10% out, but this is a 'go no-go' test that we can all do in order to save our transmissions !!!!

good one

This thread started off as a good project but the disarray and arguments early on in the thread have destroyed what was a very good idea. The original idea was to find a comparison of our VCU’s in order to obtain a pattern of “good” values, which could be considered examples of working VCU’s.

I don’t like the “wrench test” as it doesn’t give reliable results. You’d have to try it to get the feel why. If you get someone else to perform the same test on your own vehicle his or her results are too far out to be reliable. The one wheel up test works better as it uses gravity as a datum, but peeps just can’t be bothered to do the test.

The facts are:

1. Peeps can’t be bothered to perform the test – lifting a wheel etc is too much effort.
2. Testing the VCU on a Freelander isn’t enough of a test to remove all possible problems – tyre mismatch is still the biggest issue/cause of failed VCU’s as they’re overworked.
3. Testing a VCU whilst removed from Your Freelander is too difficult, as peeps need to remove the VCU first – have to admit I took mine off purely to perform this test, then put it back. (Some people fink I’m bonkers… there’s nothing crazy about me)
4. Expanding the test while making in simplifier may get more peeps interested in performing a test which displays faults caused by either a duff VCU or mismatched tyres.

If you carry out the “one wheel up test” enough times with different weights you’ll realise there’s actually a point where adding more weight to the bar doesn’t turn the bar faster, even though your actually applying more torque to the VCU. Put more bluntly, the limit point where the VCU will not accept the difference in stress across it, could be a point which we could measure. This is where it fek’s your IRD and/or rear diff when transmission wind up is applied to your Freelanders transmission during normal use. This is still at the theory stage at the moment, but I’m convinced there’s a working limit which may decrease as the VCU starts to fail.

Most people coming on ere don’t have failed VCU’s. They have mismatched tyres (either same tyres with differing tread wear or completely different tyres which int the same diameter) causing the VCU to heat up much quicker than normal. If the heat generation is high enough the VCU stays “activated/locked” for most of the time the Freelander is driven. Hence more stress than usual in the transmission. My results show motorway speeds increase the running temp of the VCU more than lower speeds. Air temp is also a factor, which increases the VCU’s running temp.

I therefore put forward the suggestion that we should find the average running temp of a VCU, and use this as a comparison. If yours is hotter than the rest, then you have a potential problem. Could be VCU or tyres. I would hope this would be easier for peeps to take part in. Also it would spot potential failures caused by tyre mismatch (most common cause of VCU failure) at the same time.

For some time now I’ve been taking regular measurements of the temperature of my Freelanders VCU. Easy to do: just reach underneath my Freelander with a thermometer. That’s temp before a trip, sometimes part way, and when I arrive. I also take into account air temp as a reference. This test is much easier to perform as your only measuring temp of the VCU. You don’t have to lift/remove anything to take the measurements. For example: travelling 3.5 miles (half at 60mph and half at 30mph) with a starting VCU temp of 10 degrees ends with an end VCU temp of about 18 degrees. Both figures rise a bit if air temp is higher. A longer journey ends with a higher VCU temp. From the testing I’ve done I get the impression there’s actually a working average running VCU temp which we could find, as opposed to just saying they’re hot.

If it goes ahead, the VCU temperature test would be known as The Turnip Test. Because it’s a good name, which hasn’t already been used, and we all know swapping a VCU for a turnip would solve our VCU problems. It’s also true the same could be said of a match.

The end result would be a known reasonable working temp of a VCU. If your VCU measured similar to the “low/good values” then this would rule out VCU failure and tyre mismatch problems. If your VCU measured higher than the average values then this would provide a warning of potential failure, which needs investigated/solved – either VCU or mismatched tyres being the fault. Since performing the tests I’ve managed to reduce my VCU’s working temp by 10 degrees on motorway journeys. Simply swapping tyres round was all it took.

I should add that I still plan to put up my “one wheel up test” results when I get round to finishing them. Need to watch loads more videos to get the results out. Recent Freelander problems have delayed this. Also a new project/toy has taken up my time.

Some good points Hippoo and, although you may well be correct, it has to be good to encourage more peeps to test (and print their results). Maybe?? we are looking for a test that is too accurate? one that can be done easily, quickly and with some semblance of repeatability, must be a good starting point. It seems that the simple torque test does show a high reading when the VCU is tightening up, so maybe good/check/buggered ranges are required?
All the data that I have states that a good working VCU locks up at about 100deg C. Obviously a seized one wont get hot, so possibly a quick temp test mite be an idea?

I’ve been thinking about this quite a lot recently. Hence The Turnip Test to measure VCU temp. I think it would be a good idea to kick start this for peeps to take part in. I also think there’s still value in the other tests for those who want to take part. The more methods we use and the more results we get, the betterer the chance we will pick something out of it. Precise is good, as we can rely on the data.

The “one wheel up test” does have a slight floor in it. The weight on the bar includes the weight of the bar itself. I have thought about making up say 5 or 10 bars (1.2m length tube welded to nuts) then spreading them round the country. Each person uses it then forwards it to another person. Peeps should not keep details of the address they’ve been told to send it to, for safety. List would be kept centrally on user names only. Or we just make sure peeps give values of 2 different test weight times, and subtract 1 from the other. (8+bar) – (2+bar) = 6kg at a particular bar length.

The “wrench test” may provide feasible values but from what I see it hasn’t on mine. But to be fare this should be tested more widely before it can be ruled out. Length or wrench played a factor when I experimented due to the added weight. Then theres the force applied which can’t be controlled.

The Turnip Test (named after vagrent but don’t tell him) is probably the one test that would get most peeps interested. Just touching their VCU by hand and finding it too hot to touch would motivate them to take proper measurements and find their cause. Hopefully via performing the “one wheel up test” thereafter to rule out the vcu as failed and look at tyres as a potential cause. I recently swapped my tyres from one side to the other. Won’t be doing that again. Have put them back now.

I can't help wondering what a vcu is doing at say 50 degrees, and if it should be replaced if it gets to this temp with 4 brand new tyres - same make/model/size? Is 50 degrees a warning point? Perhaps 70 degrees is a limt. With the Turnip Test peeps could take many measurements and give start temp, end temp, miles covered and at what fixed speed (fixed speed is easier to start with for comparison). We do the rest to display results.

Evening all,

Being new to the world of Freelanders (1st Land Rover too) I find myself a frequent visitor to this site, with most of my focus on threads relating to the transmission…

Anyhoo, as an engineer by trade I have an interest in keeping my vehicles in tip top mechanical fettle. So on a regular basis I check the health of my VCU by turning on full lock in both forward and reverse. On the flat the FL will do this on tickover.

Today I drove about 20/25 miles on A & B roads, roundabouts etc. then did some full lock turns both forwards and reverse on tickover, no problem. Just out of interest I crawled underneath and touched the VCU which was warm to the touch, but I could keep my hand on it.

I know this is not scientific, but am I correct in thinking my VCU is in good health?

By the way, I replaced all 4 tyres when I bought it in March. The previous set were all matched, although the rears did have more wear.

Thank you.

Hi Neil

New tyres is a good thing as this will rule out mismatch problems. The vcu will feel a little warm after the vehicle has been used. We don't have enough info/results on this yet but if you can hold your hand on the vcu for say 10 seconds and it's not too hot then it's below the temp I would be worried (at the moment). Turning/driving forwards/backwards on full lock isn't really a good test. Many seem to do it on here and suggest it. Auto's and diesels will overcome the force and move the car better than manuals. Also what peeps feel as tight varies. For now keep an eye on the vcu temp and if possible have a go at the one wheel up test below. With new tyres and low temp I think your vcu is probably ok.

Hi Neil

Unless it has failed "open circuit" in which case it's as good as a chocolate teapot.

Morning,

Thanks for the replies. So, Hippo are you saying I shouldn't be too worried at the moment, but obviously keep an eye on it? I could have kept my hand on it indefinitely…

The trouble is, there doesn't seem to be any hard and fast rules for these VCU's and I was looking at Bell Engineerings' website and they as good as poo pooed the torque test. But, they seem to be well regarded…

I get what you're saying about perception of what feels like binding, hot etc.

I was going to speak to Bell Eng. and probably Town & Country (my local specialist) as I don't whether it's ever had a new VCU in it's 116k miles. Hence my paranoia…

NeilTD4 said:

Evening all,

Being new to the world of Freelanders (1st Land Rover too) I find myself a frequent visitor to this site, with most of my focus on threads relating to the transmission…

Anyhoo, as an engineer by trade I have an interest in keeping my vehicles in tip top mechanical fettle. So on a regular basis I check the health of my VCU by turning on full lock in both forward and reverse. On the flat the FL will do this on tickover.

Today I drove about 20/25 miles on A & B roads, roundabouts etc. then did some full lock turns both forwards and reverse on tickover, no problem. Just out of interest I crawled underneath and touched the VCU which was warm to the touch, but I could keep my hand on it.

I know this is not scientific, but am I correct in thinking my VCU is in good health?

By the way, I replaced all 4 tyres when I bought it in March. The previous set were all matched, although the rears did have more wear.

Thank you.

Click to expand...

That's pretty much what Bell Engineering recommends!

Afternoon,

Quite right Diesel Do, that's why I tried it. Just unsure of the temperature element as I had driven further and not all in a straight line…

As I say, it's all new to me and quite a mystery, but keen to learn

Unfortunately with all these things - it aint simple.

Bell do have a very good reputation for their products (He is a member on here), but you have to remember he is about selling his products & services. He has "poo poo'd" the tests mentioned on here, but has failed to suggest a different one that can be carried out by the owner simply, repetatively and with repeatable results (they take off the VCU to test it).

As for the heat generated, just think about it - if it has seized or is very stiff, how much heat will be generated? If it has failed "open circuit" - i.e. no drive through it at all, what heat would be generated?

The best test that we have so far is either Hippoos test or the simpler torque wrench test. Until someone can demonstrate a better test, then I suggest that is what peeps do - and on a regular basis. We know it isnt infallible, and results are not an exact science. but, and here I repeat myself, ITS THE BEST WE HAVE GOT!

If peeps cant be arsed to try it, or give feedback, then the consequences are theirs.

Did anyone see how Britpart tested a vcu in LRO?

in their series about renovating a Freelander



it was very un-scientific but they seemed happy with it