VCU Torque test results

sijwhite said:

Just out of interest, where did you buy it?

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Island 4x4. I have used them for quite a few parts. Partly price, partly because they will ship to Sweden without breaking the bank.

The main reason I went for new over a refurb is, being a bit of a mechanical/engineering/physics minded geek type I have an idea on how the VCU operates. Given the almost impossible task of finding out exactly the great secret of the correct viscosity of the Dimethicone/dimethylpolysiloxone that GKN used in the original system I am not convinced that a refurbed one has the correct viscosity in it. from my research I am guessing it is 100 000Cs. It is also like finding rocking horse **** here in Europe although Dow make it and it is available in the USA. Just to note also, it is considered safe for skin contact etc. It had better be! as it is one of the most common ingredients in most skin and hair care products on the market today, although at the lower viscosity range of around 1000Cs. (mm2/sec)

How geeky was that!!

One more thing that can affect the time on this 45' test is the temp of the oil in the rear diff. This will probably have more of an affect than the temp of the Dimethisone in the VCU. Condition/temp of the wheel bearings and grease will also make a difference. Mine was done cold. I fitted the new and tested straight away just to get a benchmark.

Just to add to my previous geeky post.
Dimethicone is also the old kids toy "Silly putty". I am guessing that the Dimethicone in my old VCU is probably as viscous as silly putty now.

Some interesting posts there Portchy. Well done. Test results from recon vcu's are normally quicker than new units, when doing the one wheel up test. Often peeps feel their recon replacement is betterer than the one removed as the feeling of tightness will reduce. It's doing it for a reason. The recon vcu has been re-filled to give reduced stress across it.

Hippo said:

One Wheel Up Test times can be accidently increased if the handbrake int fully released or if the rear brakes are catching.

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I was kinda suspicious of this at after my vcu done there was a noticeable reduction in tightness on full lock to the extent that I thought I had been ripped off with a loose vcu. Subsequent one wheel up test as above, at 25- 30 secs ish I was happy because I was moreworried the weight was goin to hit the floor straight away, Just for good order I checked the free rotation with both rear wheels up and it was ok. With this and the mud test i was happy. Mud test performance was as I would like to see. Watching wheels closely, the front wheels had barely slipped one rotation before the rears took up. Is this what everyone would be happy with on their freelander?

Hippo,
I did the wheel up test as follows:

- 206,000 miles
- 5kg weight 1m from hub
- falling from 45 degrees to horizontal
- 50 seconds

is this good or bad ???????????

not good

musky81 said:

I was kinda suspicious of this at after my vcu done there was a noticeable reduction in tightness on full lock to the extent that I thought I had been ripped off with a loose vcu. Subsequent one wheel up test as above, at 25- 30 secs ish I was happy because I was moreworried the weight was goin to hit the floor straight away, Just for good order I checked the free rotation with both rear wheels up and it was ok. With this and the mud test i was happy. Mud test performance was as I would like to see. Watching wheels closely, the front wheels had barely slipped one rotation before the rears took up. Is this what everyone would be happy with on their freelander?

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The vcu does activate quite fast. I've tried filming this before using high speed frames on slippery surfaces. It will always have some resistance across itself.

tkitt said:

Hippo,
I did the wheel up test as follows:

- 206,000 miles
- 5kg weight 1m from hub
- falling from 45 degrees to horizontal
- 50 seconds

is this good or bad ???????????

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That's a lot higher than average. We don't have enough results to know for sure if it's too high, but it's certainly much higher than the average we have.

It's considered impossible for Freelanders to get to that mileage without transmission failure. So with that in mind either yer tyres are balanced perfectly, we're all mad and missing something, or yer brakes are binding. If not then yer vcu is restricting a lot more force across itself than normal, which is bad luck. Can you jack up both rear wheels and release the handbrake to see if they spin freely? If they are then think about getting the vcu replaced.

While I'm ere... A lot of peeps ask about using the wheel nuts for the One Wheel Up Test instead of the 32mm centre nut.

We would like peeps to use the centre 32mm nut as it's much stronger then the normal wheel nuts. A 1.2kg bar with 8kg on the end put a force on the nut of 94Nm. If you were to increase the weight to 10kg that would apply 117.6Nm to the nut. If that were to be applied to the wheel nut, it would be higher than the manufacturers recommendation of 115Nm. Yes I know it's not much more, but I don't want to take the risk of someone applying much higher values like 294Nm with a bigger bar (2m) and heavier weight (15kg). Also 94Nm on the wheel nut would give a slightly different time to the centre 32mm nut, due to being offset from the centre.

Thanks Hippo / Mad Hat Man, i knew you were going to say that

Even with that reading i don't think i have much resistance when reversing on full lock ?. I will check the rear brakes however, I just did an overhaul on them for the annual NCT (MOT) so i don't think there's any problems there.

I think what your doing here is very worthwhile, but it will take time before a pattern can be established.
In the meantime I'm going to be stubborn and carry on with the original VCU, I'll let you know how i get on and try to get some regular results.

With regards to the tyres, I'm very careful to keep them matched, i also assume that travelling at 50-60mph on B roads puts far less strain on the transmission than motorway travelling at 80-90mph. Would i be right in saying that any mismatch is exaggerated as speed increases ?, or is it just a set percentage based on the diameter ?, i cant work that one out !

I look forward to seeing the ongoing results, i must admit that i totally missed this thread as it was a sticky, i just got into the habit of scanning the latest threads, I'll keep an eye on it from now on.
Regards
Tkitt

Ok just done a test as I've feeling a bit of tightness when parking up in the supermarket car park.

2001 Td4 Auto. Mileage 122,000 and from what I can see its the original VCU date stamp 00.

Today outside temp is around 6 deg. My Freelander hasn't been used for a couple of days.

Offside rear wheel jacked up, 1.2m ally spirit level with ratchet and 32mm socket strapped to one end. Weight is 9.4kg, (two old brake discs and a calliper). Timed through 45 deg came to 40 seconds.

I'm guessing that's to long and the VCU is stiffening up?

sounds like it - I would think closer to 20 secs is the norm (if one exists)

Nodge68 said:

Did a quick VCU test today. I only had time to do a 10Kg test. My car is 2001 V6 with 31500 miles on it.
10 Kg's @ 1.2M = 11 seconds

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Well here's my results for this year. The car has travelled 6000 miles since the last test but the VCU has been sat on my workshop bench for 3000 of those miles.
This time I used a 1m lever with 8kg hung on it. It took 45 seconds to turn 45° which is much longer than last time even if I factor in the shorter lever and lower weight.
I'm thinking that maybe I'll do the Turnip Test next for safety.

looking iffy, Bodge

The Mad Hat Man said:

looking iffy, Bodge

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Yes is does
I'm going to test it again next week as the test I did today was done once I refitted the props without the vehicle being driven.
It drives fine without hopping in reverse and only minimal braking effect.

Nodge68 said:

Did a quick VCU test today. I only had time to do a 10Kg test. My car is 2001 V6 with 31500 miles on it.
10 Kg's @ 1.2M = 11 seconds

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Nodge68 said:

Well here's my results for this year. The car has travelled 6000 miles since the last test but the VCU has been sat on my workshop bench for 3000 of those miles.
This time I used a 1m lever with 8kg hung on it. It took 45 seconds to turn 45° which is much longer than last time even if I factor in the shorter lever and lower weight.
I'm thinking that maybe I'll do the Turnip Test next for safety.

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10kg x 1.2m x 9.8 = 117.6Nm
8kg x 1m x 9.8 = 78.4Nm.
I wonder what it would be like after a drive. Even half a mile will turn the vcu enough to mix the fluid around if it's sunk to the bottom.
You may be about to join the club of those who have tested regular, and spotted their vcu change, if it is changing... the Ternip Test is yer friend in situations like this. I's amazing to think a test named after vagrant would be so useful.

Hippo said:

10kg x 1.2m x 9.8 = 117.6Nm
8kg x 1m x 9.8 = 78.4Nm.
I wonder what it would be like after a drive. Even half a mile will turn the vcu enough to mix the fluid around if it's sunk to the bottom.
You may be about to join the club of those who have tested regular, and spotted their vcu change, if it is changing... the Ternip Test is yer friend in situations like this. I's amazing to think a test named after vagrant would be so useful.

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Well i'v just realised that things don't appear as bad as I first thought.
The torque figure that I applied of 78.4nm seem high, but this torque figure isn't seen by the VCU, the diff is multiplying the rotation speed of the VCU by the diff ratio. This multiplication of speed will reduce the torque by the same figure.
The maths works like this.
Torque at wheel is 78.4 nm this is divided by the diff ratio of 3.21. This equates to 24.41nm or 18ftlb seen by the VCU!! It doesn't seem much to me
Any thoughts on my theory?

yu ignore the diff as all the results are comparative, not absolute.



I dont believe that torque is affected by ratios, just thro losses.

but its been a long time since I needed to work it out

You are rite as the new figures recorded has increased compared to the figure done last year.
The actual torque required to turn the VCU will be less than that at the wheel by the diff ratio less any gear losses!!
The VCU took 45 seconds to rotate 144° with a torque of 18ftlb applied. I can't see it needing to turn that amount on the road so for now I think I'll be ok.