Correct VCU silicone oil

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Alibro said:
My 'how to' with some improvements by others. Please add to this thread if you have improvements of your own.
https://www.landyzone.co.uk/land-rover/how-to-recondition-a-vcu-yourself.307445/

What I used
http://www.ebay.co.uk/itm/Silicone-...898414?hash=item36137880ee:g:ToYAAOxyJX1S~Ufp
Click to expand...
Thanks a bunch!
What is the beaviour of your Freelander? Does it "lock" when front loses traction? As I see from your DIY I am using low grade silicone oil and also small quantity...
 
I used the car for some off road driving and it was very good. I couldn't say if the rear wheels are pushing as hard as they would with an oem VCU on steep rocky hills, as I don't have an oem one to compare it with but for 99.9% of what Freelanders are used for it is fine. In a muddy field I saw all four wheels spinning at the same time.
 
Alibro said:
I used the car for some off road driving and it was very good. I couldn't say if the rear wheels are pushing as hard as they would with an oem VCU on steep rocky hills but for 99.9% of what Freelanders are used for it is fine. In a muddy field I saw all four wheels spinning at the same time.
Click to expand...
Ok. That is really cool :)
And on tarmac on small manouvres did you feel any drag, like when the VCU is completely seized?
I ask this because I am testing different grades of silicone oil to see what is the best for an everyday use and some ocasional greenlaning.
 
I feel a little drag while reversing full lock but this is completely normal and is felt by folk who have fitted oem VCU's. I prefer to test with the One wheel up test as it is better for comparison with other cars and results put up by other folk.
 
Alibro said:
I feel a little drag while reversing full lock but this is completely normal and is felt by folk who have fitted oem VCU's. I prefer to test with the One wheel up test as it is better for comparison with other cars and results put up by other folk.
Click to expand...
Thumbs up man :)
Really great post.
In the meanwille I will try different grades of silicone oil, next try will be on 30,000 cst, if the beauvior is not of satisfaction, I will try higher.
The quantity of 150 ml is the same for all the grades?
 
I believe @jonaf used thinner fluid (30k cst) and if he wanted a tighter VCU he used a grease gun to inject more. If he wanted it looser he let some out. This ties with my experience as the first VCU I refurbed was too tight giving a 1WUT time of 1 minute and letting some fluid out brought it back down to oem (ish) i.e. around 20 seconds.
I think the quantity is as important as the type.
 
Alibro said:
I believe @jonaf used thinner fluid (30k cst) and if he wanted a tighter VCU he used a grease gun to inject more. If he wanted it looser he let some out. This ties with my experience as the first VCU I refurbed was too tight giving a 1WUT time of 1 minute and letting some fluid out brought it back down to oem (ish) i.e. around 20 seconds.
I think the quantity is as important as the type.
Click to expand...
Very cool.
I have read a post of @jonaf about the 12,500 cst. As I only have 120 ml, tomorrow I will try to inject some more 30 or 40 ml and then put the wheels spinning on a workshop ramp (elevator) and see if the VCU "locks"
 
The fluid is a PDMS (google it!). Not non-netwonian in operation as slip increases until it 'locks'.

It can be called Silicone Oil - however, 12,500cst has a consistency of .... custard. If you want a VCU that will drive you up a muddy slope via the back wheels, you'll need something like 100,000cst. If you just want a bit of assist from the back to improve the handling and get you moving on the flat, then you need to be looking to about 30,000cst at least.

With 12,500cst - you might as well take the props off.

Just my observations of observations.

And you'll need a correct air gap - but less observations on that - although if you search on here for posts by @htr and 'gap' he put up an observation recently!
 
I suspect 12,500cst fluid will work fine on a ramp but will slip a lot when stressed and won't really work at all if you are green laning and have a front wheel in the air, especially if you have less fluid than standard. Adding more might tighten it up a bit but it will never be as good as oem.
Just my best guess so would be great to hear your real life experience.
 
We got a few inches of wet snow yesterday. Climbing steep hills on this slippery surface is no problem with well worn studless winter tyres. The TC will kick in now and then when a front wheel spins but it is no problem to stop and start in the middle of the slope.
The VCU i currently use is filled with 12.500 cst fluid but I can't tell much difference between this and one with 30.000 grade The trick is to pump fluid into the unit until it goes solid and then let a few cc out. If it's still to stiff, let out some more. My Freelander goes wherever my wife's Suzuki S-Cross goes with the 4WD in "lock" mode on brand new winter tyres.
 
Last edited:
jonaf said:
We got a few inches of wet snow yesterday. Climbing steep hills on this slippery surface is no problem with well worn studless winter tyres. The TC will kick in now and then when a front wheel spins but it is no problem to stop and start in the middle of the slope.
The VCU i currently use is filled with 12.500 cst fluid but I can't tell much difference between this and one with 30.000 grade The trick is to pump fluid into the unit until it goes solid and then let a few cc out. If it's still to stiff, let out some more. My Freelander goes wherever my wife's Suzuki S-Cross goes with the 4WD in "lock" mode on brand new winter tyres.
Click to expand...
I suspect lower CST fluid will be much less of an issue on snow than it will be green laning. The torque required to drive a car up a hill with a front wheel in the air will be much more than that needed on snow.
Still good to hear how good the Freelander is compared to other makes. ;)
 
GrumpyGel said:
The fluid is a PDMS (google it!). Not non-netwonian in operation as slip increases until it 'locks'.

It can be called Silicone Oil - however, 12,500cst has a consistency of .... custard. If you want a VCU that will drive you up a muddy slope via the back wheels, you'll need something like 100,000cst. If you just want a bit of assist from the back to improve the handling and get you moving on the flat, then you need to be looking to about 30,000cst at least.

With 12,500cst - you might as well take the props off.

Just my observations of observations.

And you'll need a correct air gap - but less observations on that - although if you search on here for posts by @htr and 'gap' he put up an observation recently!
Click to expand...
Ok mate.
Thank you.
 
After some tests, I believe that I am satisfied with my Freelander VCU beaviour, 160 cc of 100.000 cst silicone oil and it is very satisfactory both on the road and off road, tried some axle crossing and the Freelander just overtook the obstacle!
 
Mike Nascimento said:
After some tests, I believe that I am satisfied with my Freelander VCU beaviour, 160 cc of 100.000 cst silicone oil and it is very satisfactory both on the road and off road, tried some axle crossing and the Freelander just overtook the obstacle!
Click to expand...
Good to hear, what sort of time are you getting with the one wheel up test?
 
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