VCU Torque test results

celt69 said:

This might be a really thick question? so no doubt will get some sort of rude response, any way here goes. Has any body spoken to Land Rover and told them that we are not happy that the vcu is none repairable also what should be the optimal time for the weight test or how is the best way to test it.:behindsofa:

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Good question. There isn't an optimal age or mileage to change the vcu that we know of. Anyone stating there is can't supply supporting evidence. I asked a main dealer and they talked about the vcu and put a question into technical at LR on my behalf. Result came back about potential failure and how to spot it. Dealers take them off and test them if required. About 3 to 4 years ago when we had the opportunity to test vcu's which were only 4 years old we struggled to do so. Peeps just can't be bothered etc. Those vcu's are now 7 to 8 years old. The difference over time would have given us an indication how a vcu ages with time, and the effects. The only guaranteed solution to vcu problems is to remove it. But that kind of defeats the ownership of a 4x4.

or replace it

jamesmartin said:

or replace it

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Yes but that only fixes the problem for a certain amount of time. Many years but not a permanent fix. If we had results of vcu's degrading over time then we could make a prediction based on facts.

Hippo said:

Yes but that only fixes the problem for a certain amount of time. Many years but not a permanent fix. If we had results of vcu's degrading over time then we could make a prediction based on facts.

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true but its allways been common to have your gearbox done at least once in most other models ,rrc classic v/c lasted roughly 10 years 100k but obviously each vehicle varied due to usage ,tyres etc so some greatly more others less ,getting figures for averaging is a good thing ,very useful as a diagnostic tool amongst much other

jamesmartin said:

true but its allways been common to have your gearbox done at least once in most other models ,rrc classic v/c lasted roughly 10 years 100k but obviously each vehicle varied due to usage ,tyres etc so some greatly more others less ,getting figures for averaging is a good thing ,very useful as a diagnostic tool amongst much other

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Yes it's a good diagnostic. Woud be nice to be able to predict failure in the near future from results or at the very least spot vcu's which are way off what the average is.

Will be doing the one wheel up test this weekend on mine as it's about 6 months since it was last done.

When a vcu fails in a classic rr what's the result?

bust front diff ,prop ujs usually first but could be rear diff if weak and tyre wear ,quite often not noticed for some time

jamesmartin said:

bust front diff ,prop ujs usually first but could be rear diff if weak and tyre wear ,quite often not noticed for some time

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Thanks.

Hippo said:

Yes but that only fixes the problem for a certain amount of time. Many years but not a permanent fix. If we had results of vcu's degrading over time then we could make a prediction based on facts.

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i think yu is asking for the MTBF? most manufacturers have a guide for that.

ere Hippoo - from the Ashcroft site.... (for the Rangie)

RRC, Workshop Manual, Section 41 Transfer Gearbox, Overhaul, Dismantle, Inspection & Overhaul.

You can either do this test on the bench or in the car with the handbrake on and one front wheel lifted.
Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 ?C.
1) Secure the output shaft ...
2) Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.
3) If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25? - 30?. If no rotation or a greater force is required, unit requires replacing.

27 Nm = 20 lbf-ft 20 Nm = 15 lbf-ft


thats what we need for the freebie

The Mad Hat Man said:

i think yu is asking for the MTBF? most manufacturers have a guide for that.

ere Hippoo - from the Ashcroft site.... (for the Rangie)

RRC, Workshop Manual, Section 41 Transfer Gearbox, Overhaul, Dismantle, Inspection & Overhaul.

You can either do this test on the bench or in the car with the handbrake on and one front wheel lifted.
Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 ?C.
1) Secure the output shaft ...
2) Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.
3) If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25? - 30?. If no rotation or a greater force is required, unit requires replacing.

27 Nm = 20 lbf-ft 20 Nm = 15 lbf-ft

thats what we need for the freebie

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Have seen something similar before to test electric screwdrivers with a preset torque limit for production. Turns a dial to display strength.

If I understand it correctly he's putting a known torque on one end of the vcu and holding the other end stationary. Then counting the turns. A fixed torque will give N number of turns per counting period. If N reduces then the vcu is fighting back against the supplied torque and therefore limiting the number of turns, during the counting time period. That's not that far away from the principle of the one wheel up test which applies a torque during 45 degrees to the horizontal. Ashcroft's test is able to supply the torque constantly for longer periods of time which is a betterer test. One wheel up just gives a sample but repeating it constantly gives the same result each time from what I've seen. Previous idea of a rope round the wheel with a pulley allows for constant torque for longer periods than what the one wheel up test can do (unless the vcu is seizing then may will take much longer). Interesting find. Have looked through Ashcroft Transmissions site before so I may have seen it before. Dave's good at keeping the site up to date. Will have a think about this. Electric drill with torque limit to supply the force perhaps...

MHM,

Had a play with a battery drill with different torque settings today, in order to try to mimic the professional VCU bench test. Used different cables to see if I could set the drill torque so it would only just twist the cable, then keep the torque applied the same as the cable fights the torque when the drills torque clutch thing slips. It worked ok. I was using half inch aerial cable and some 16 or 24x 7/0.2 multicore. Applied torque to see it twist then reduced the torque and tried again. You could see the drill turning the cable less and the torque stayed the same as the clutch slipped. This is similar in nature to the test above with a motorised constant torque fed into the VCU.

The professional test must use a known measurement of constant force, applied to a VCU to turn it. If the resistance across the VCU is greater than normal the VCU will turn slower. Hence a reduction in revolutions per time period. Counting the revs per time period gives an indication of a the resistance across the VCU, and therefore tells you how hard it's working. Lower revs = greater resistance. It's certainly the way to go to test a VCU more thoroughly. The one wheel up test only tests for a brief period of time. This more professional way would allow us to see the effect on a VCU over a few minutes. Sadly this test method would be more involved than the one wheel up test which most peeps don't carry. So although it's good, peeps probably won't have a go. I guess you could lift one wheel and apply the drill torque via the centre nut too. Different drills would give different torques which would hamper result comparison.

The idea of constant torque (applied force) is interesting. Taking the following:

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

For a 1.2m bar and 8kg weight:

Torque = 8 x 9.8 x (1.2 x cos Angle) = torque in Nm

A one wheel up test with 1.2m bar holding an 8kg weight travelling 45 degrees to the horizontal gives an applied force ranging from 66.5Nm to 94Nm as it turns 45 to horizontal.

The rope round the wheel and up over a pulley option gives the same constant applied force throughout the test. Bar length is the same as the radius of the wheel. Weight on the end of the rope is effectively connected to the theoretical bar (wheel radius). Hence this would be 0.34m bar with 8kg weight at 0 degrees (angle = 0 as the rope follows the circumference of the wheel) = 26.7Nm constant. That's applied via the VCU via the diff but could also be applied direct to a VCU if tested on a bench.

Regardless of what tests we come up with, or the validity of their approach, the biggest problem of all is to get peeps to carry out the test. Turnip test being the easiest of them all.

Just seen that. You have made some very valid points, particularly the last!
The problem, as I understand it, is there is no defined perimeters to test, and it isnt in any repairers interests to assist, just to release frightening and, in some cases, incorrect information.
feedback is the critical factor.

The Mad Hat Man said:

Just seen that. You have made some very valid points, particularly the last!
The problem, as I understand it, is there is no defined perimeters to test, and it isnt in any repairers interests to assist, just to release frightening and, in some cases, incorrect information.
feedback is the critical factor.

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Agreed. I'm going to ask the local stealer to put in another request to technical for me about the parameters and how to define when it's beyond it's usuable life. Also going to approch GKN as they made the original VCU's for LR. May not get anywhere as design spec is theirs to own but it's worth a try.

Nothing to loose .

Hippo said:

Agreed. I'm going to ask the local stealer to put in another request to technical for me about the parameters and how to define when it's beyond it's usuable life. Also going to approch GKN as they made the original VCU's for LR. May not get anywhere as design spec is theirs to own but it's worth a try.

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Best of luck I tried that, even going through the back door via a neighbour who worked for JLR transmissions at Gaydon. LR still don't officially admit there is a problem with the vcu.

The best test is the known weight, applied via a known length of bar, directly on the the spline of the vcu, as per the video I made. The 1 wheel up test is OK too, but just decide on 1 weight and 1 length, no need to complicate it

austen said:

Best of luck I tried that, even going through the back door via a neighbour who worked for JLR transmissions at Gaydon. LR still don't officially admit there is a problem with the vcu.
The best test is the known weight, applied via a known length of bar, directly on the the spline of the vcu, as per the video I made. The 1 wheel up test is OK too, but just decide on 1 weight and 1 length, no need to complicate it

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The plan was to calculate torque (applied force) from the bar length and weight, in order to gain a more precise result. Torque v time to turn 45 degrees to the horizontal. This would get round the problem of owners using different lengths and weights, so complexity wouldn't be an issue as owners could use whatever they had available and we would convert the results for them. We settled on 1.2m and 8kg somehow.

I agree directly testing the VCU is more precise as it takes out the chance of a rubbing brake shoe etc and negates the diff gearing. The one wheel up test allows peeps to do the test without removing anything. Hence we thought it would be more popular. To date my video has 32751 views. 2477 views from links on LZ. It's been reposted by others all over the world on many forums.

Plan B is a VCU shaped hot air balloon over the lode lane factory. Plan C is top secret but easier than plan B.

I Like plan b!!! Lol!

Really can't see the point of calculating the torque as it all depends on the rate of how the force is applied, it just over complicates things. What simpler than a known length of bar and weight, more people can knock that up in the garage than something that requires torque readings.

BTW, not poo pooing any of your ideas/plans, just adding my input based on experience.

I doubt very much you will get Any torque figures from LR, let alone an acceptable range before bit needs changing. I worked at gaydon for years, the amount of dead wood there is staggering, with only a few actually knowledgeable and useful people there, a lot of who are contractors or permanent members of staff that get frustrated so move on

austen said:

I Like plan b!!! Lol!
Really can't see the point of calculating the torque as it all depends on the rate of how the force is applied, it just over complicates things. What simpler than a known length of bar and weight, more people can knock that up in the garage than something that requires torque readings.
BTW, not poo pooing any of your ideas/plans, just adding my input based on experience.

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All peeps need to do is post up results containing:

Length of bar from pivot point to the bit where the weight hangs off the bar
The weight used
Time in seconds to turn 45 degrees to the horizontal

If they choose to use a 1.2m bar with 8kg weight then this is ok. If they don't have a 1.2m bar then they can use what they have. I don't so I tie wrap a length of wood to my ratchet to make 1.2m. I use liquid bottles or large sockets and D shackles as the weights. I measure them with kitchen scales. I did several different weights to see the effect, which is optional. You can use anything as long as it still hangs off the ground when the bar is horizontal, and weighs enough to turn the wheel at a reasonable speed. If it's too fast or too slow then change the weight to suit. Time wise it's better to film it and watch afterwards to get a more precise start/finish position.

The use of torque allows me to compare results of different bar lengths and weights. What we're essentially doing here is applying a force which is generated by the length of bar and the weight:

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

For a 1.2m bar and 8kg weight:

Torque = 8 x 9.8 x (1.2 x cos Angle) = torque in Nm = 94Nm

Hence 1.2m with 8kg is 94Nm using the fixed point of 0 degrees which is the horizontal position (ignoring the fact that force changes due the angle of the bar (cos Angle bit) for this explanation, which isn't a problem as its proportional acceleration). The result for 1.2m and 8kg is roughly equal to 0.75m bar with 13kg weight as both options apply roughly the same force of 94Nm. Hence why I like the option of force applied calculated from the results given.

Peeps don't need to do the maths to calculate force. I'll sort that out for them. They just post the requested 3 items above.

The biggest problem we face is peeps not bothering to carry out the tests. If they don't have a suitable size socket then buy one. It's a hell of a lot cheaper than a VCU or transmission failure. I'm watching my VCU's results change over time. Have tested it on the bench too. I think MHM and I have gone as far as we can with this.

Does anyone know the difference between a v6 VCU and the other one which fits all the other non v6 Freelanders? I know the v6 doesn't have the damper fitted and I guess it won't have holes or mounting points for the damper.

TOR000010 = 1.8k series rover petrol, 2L rover diesel and Td4 BMW diesel
TOR000040 = v6 (rover kv6) petrol

Hippo said:

Does anyone know the difference between a v6 VCU and the other one which fits all the other non v6 Freelanders? I know the v6 doesn't have the damper fitted and I guess it won't have holes or mounting points for the damper.

TOR000010 = 1.8k series rover petrol, 2L rover diesel and Td4 BMW diesel
TOR000040 = v6 (rover kv6) petrol

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Its the same unit in operation, but v6 has no damper or the mounting face for it. Also the hanger bearings have a 25mm spacer on them to hang it lower. But to be honest you can just run a normal one in its place