VCU Torque test results

Do you not feel that even with the knowledge you have now it still doesn't offer a carefree ride?

 

lol, I think it would be a bit like after putting it back after the rebuild - s**t scared at first that it will all go bang, but after a while it will be fine. I am though chatting to a chap who has built a diag device that talks to the engine's ECU and he's extending on it to talk to the Wabco ABS module. I want to take that and hook it up to a Raspberry Pi (or similar) to constantly monitor wheel speeds in case there's another flat - plus I want to bung some temp sensors on the IRD, diff etc and monitor them real-time. HTR has fitted a TPMS to his Freelander - that's probably a sound investment on Frelander!

 

I don't worry about mine John. I just drive it. My VCU has 115K miles on it. It appears to be about 50% stiffer than a new VCU on the OWUT. However it's not skipping tyres on full lock, so it's got some time yet.
I do have a full set of matching tyres and I check the pressures fortnightly. Otherwise I just enjoy driving the thing. Life is to short, to be worrying about things like VCUs.

 

I thought I'd post my experience here of reconditioning a VCU by flushing it out. I don't believe this can ever be as good as cutting the top off and properly cleaning every disk but many of us don't have a welder or the skill to use it so without spending hundreds this is your only other choice, this is copied from other threads so may be a bit disjointed.

1. Drill two holes in the end the appropriate size for the tap and bolts or grease nipples you intend to use. I used M10 Extra fine as I hoped the extra number of threads would make it stronger. I think the drill was around 8.9mm but it's easy to find tables showing the correct drill size for your tap.

2. Leave it overnight for some of the gunge to ooze out

3. Tap the holes now so that any swarf will come out with the gunge as you clean it (use a 1/4" extension bar from a socket set to extend the tap).

4. Clamp it in a vice and using a syringe or a small funnel pour in as much white spirit as it will take.
5. Put the rear propshaft onto the splines and stick a long crow bar (or similar) through the UJ and start turning to mix the white spirit with the fluid still in the VCU.

It might be a good idea to tidy your bench before taking photo's and posting them on the internet.

6. Repeat points 2 through 4 many many times over a week or so until there is more white spirit pouring out than gunge and the VCU is quite easy to turn.
7. Once happy it is as clean as your going to get it then leave it to drain for a few days turning repeatedly to try and get rid of as much white spirit as possible.
8. Once drained start injecting new fluid in with a big syringe while turning to get the fluid down the VCU and inbetween the disks. You might find you need to screw in the bolts to stop the fluid coming back out.


9. Repeat until you have approx 150mls of 100,000 cst fluid in the VCU
10. Screw in your bolts, refit to the car and drive for a few miles to really mix everything up.
11. Do the one wheel up test and if too slack squirt in a wee bit more fluid (easier said than done) or if too tight let some out then drive for a bit more and test again.
Note, It might be worth putting in a little more than 150mls of fluid as it will be much easier to let excess out than put more in. I plan to add another 10 - 20mls on top of the 150 for that reason. Also a little ends up spilling out so it's hard to measure exactly how much made it into the VCU.

Tips
If using grease nipples they are very shallow so no problem but if using bolts you'll need to cut them down to approx 9mm. I cut mine to 10mm as I'm using a copper washer which is probably unnecessary but I have them so why not.
Drill the holes as near centre as you can (half way between the shaft and the edge) Too near the edge and you'll hit the side wall and too near the shaft and your bolt will foul the curve at the shaft.
Buy a good quality tap and tap handle. I have a cheap tap which is useless and a reasonably good one which is great. I used metric extra fine M10 but fine or even normal would be OK if using bolts instead of grease nipples. Grease nipples are very shallow so don't have much thread to grip and if your tapping isn't perfect you could easily strip the threads.
Get a good big syringe with a large nozzle.
Weigh the fluid before you start and at the end to confirm you have the right amount in.
Pour the fluid into the syringe. Trying to suck it into the syringe will introduce so many air bubbles you wont be able to use the markings on the syringe to measure it (and its painfully slow).
Both cleaning and filling are very very messy jobs. Be warned and have appropriate gloves and cleaning materials.
To find the silicone fluid go to ebay and search for 100000 cst

Disclaimer
I haven't finished yet or tested it so will report back once done. I'm only posting this here to show how I did it and am not claiming this is the correct method or saying this is how you should do it.

Edit
VCU is back on the car and giving a OWU time with 5kg weight and 1.2m bar of approx 20 seconds. This is pretty close to OEM I believe so happy it isn't too tight. As pointed out by others, the OWU test cannot confirm the VCU works as a VCU so I tested it in a muddy field and happy to say all four wheels were spinning at the same time. Still to test on a steep stony hill so can't confirm how much torque will be transferred to the rear wheels.
The only concern I have with using this method to refurb your VCU is that there is bound to be residual old fluid mixed with white spirit which is now mixing with the new silicone fluid. This may or may not have an effect on the performance but if this VCU is as good as the last one I did the old way then I know it works fine on rocky hills so I'll be very happy.

 

Excellent write up Alibro mate ...

Can I just clarify

Do you mean - weight the VCU complete before and after as this would be an excellent way to ensure the correct amount - you could use a simple balance to ensure it is correct.

Also, a few ideas that may (or may not ) help.
The gunge that first comes out after drilling the holes can be a damn good tester for solubility of various fluids to aid cleaning.
If you place small amounts of the gunge in separate containers and then experiment with various solvents you may find a better one. White spirit (mineral spirit as the yanks call it) does apparently act as a solvent for silicone oils. Toluene is supposed to be better - worth testing ? might be ....
I believe a lot of lacquer thinners are toluene based ?
Just a thought....

Again, superb write up - should definitely be made a sticky in it's own right in the 'technical help' forum
Nice one !
Joe

 

I agree Joe!

Alibro, reading your write up makes this task look an absolute doddle!

 

Not so sure it sounds like an "absolute doddle" - but a great write up

 

Thanks guys. It's no doddle as it is slow and your arms will be tired turning the damn thing but easily doable by anyone who has a drill.
As for weighing yes if you have a scale suitable to weigh the VCU to single grams then that would be ideal. Mine are kitchen scales which only go up to 2kg so I weigh the bottle of fluid instead but also measure using the scale on the syringe.

 

Naw mate, you don't need a special scale at all, just rig up a simple balance scale. Add two bolt heads (heads only) to the first 'weigh' - that will equalise the additional weight you are adding.
Just use a simple pivot point as friction-less as possible hang vcu on one side and add weight on the other until it balances exactly. You dont even have to know the weight.
Just ensure you hang the vcu from exactly the same point when re-weighing.
We balanced 2 blade microlight props with that method. perfect - you can add a tiny wood screw on one end when balanced and it will tip - extremely sensitive.
The appliance of science
Joe

 

Lol, far too precise for me. I'm more of a, have a go and wing it kinda guy but measuring the way I did is probably close enough.

 

lol, -- yes, but it would be a very interesting exercise as one would be able to tell within a knat's todger the exact amount of fluid used in manufacture
Even with changes in properties of the fluid the 'weight' will not change. The original specific gravity of what comes out and what goes in should be more or less identical. If not actually identical.
Whatever state the vcu is in it will weigh the same as when it left the factory including fluid. A good way (weigh lol ) to know what the original had !. - also to enable you to match it in the context of fill capacity for hump mode operating point.

I commend the idea to the house...

 

Excellent stuff.

 

I go for weeks without checking tyre pressures.

 

I'm sure there will be a reasonable amount of metal suspended in the fluid that comes out from wear on the plates. I know Alibro has said that the plates do not look worn when he's opened up a VCU - but I'm still convinced that it happens. This would affect calculations by weight.

 

Hi Grumpy
Possibly, but IMO - probably not measurable. 1 gram (which would only be = to 1 mil fluid (1cc) - would be a hell of a lot of swarf. A magnet sump plug covered in particles will probably not contain more than a gram if fully coated. That kind of wear is self evident.
You would see particulates in the fluid if any wear was evident.
The metal is also ferrous, so a neodymium magnet in the gunk catch tank would pick up any trace. - I doubt you would fine any of any consequence at all.

I agree that there will probably be some caclulable extremely MINUTE wear, however, I would say it would not be measurable at all - even if we are talking of a sub gram resolution.
Joe

 

The reason I believe there is minimal wear is that the disks never come in contact with each other because there is always a layer of fluid between them. Also when you look at the disks there are no visible wear marks.
As for perfection in the weighing I don't know how important that would be as other factors like how well you cleaned out the old fluid or how much white spirit (or whatever you used) was left in it will effect the weight and VCU performance. Unless you cut the top off you'll never clean it out fully and if you do cut it off it would be impossible to weld exactly the same every time.
With so many variables it's probably best to just add a little more fluid than necessary, drive for a few miles then test. If too tight then bleed some fluid out and test again until happy. 150g was the the amount I used the first time but that was a perfectly cleaned VCU so this time I suspect it will need a fair bit less.

 

Hi all,

Back in the land of 'LANDY'.
53 plate Freelander S TD4.
Just done a quick test on the VCU with a socket on a rear wheel nut with a Britool 18" breaker bar, guess what, took a hell of a lot of effort to turn the wheel (no brake binding!).
Would appear from the posts I need to (sooner than later) remove the rear prop as a temporary measure to save the rest of the transmission from failure.
Driving home from work yesterday, it appeared to have a gear whine, so thought I would try the 'slip' test.......

Paul S.

 

It would be prudent to remove the props, just in case

 

Let's just remind everyone reading this thread, where the original idea for the OWUT came from, and why the data collected here is so important.
These quotes came from Austen of Bell Engineering. The respected Freelander VCU and IRD reconditioners. The OWUT came about due to the number of IRD failures on the forum.
Here's a few of Austen's words.

.

All this thread's information is available here.
https://www.landyzone.co.uk/land-rover/an-open-letter-to-austen.148283/

All that is needed is continuing info to be fed into this threat.
Thanks.

 

Interesting reading. As pointed out other than compensating for the gearing issue it's the same as bench testing them which is a service currently available.