DIY VCU service

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Datatek said:
Is Turps actually thinning the silicon?
Click to expand...
Seems to make it more fluid, if mixed with the fluid in a pot it does combine together....makes it thinner and more oilly like...its also a lot less sticky... its actually looks revitalised. .

But getting it to mix in the vcu properly is a problem.

Its coming out better...but not sure if turps is ideal...might try paint thinners on the fluid tomorrow
 
I have been reading this with intrest and so last weekend I finally got the disc cutter on one of my old vcu's I cut the top plate off and removed all the plates from inside the housing (50 in total). The fluid was so thick that I had to use over 2 liters of petrol to thin the fluid enough to remove all the plates. For your infomation I could not turn the spline by hand until I had all but the last 2 plates removed.
I then steam cleaned the plates and housing to ensure that all fluid was out.
I have ordered some 30,000cst oil from ebay and will refill and weld back the 2 halves of the assembly when Im next at home (probably another 2 weeks).
Will also take some pics and try and post them up here.
 
That's great stuff...I was thinking about cutting mine open as its a pain to get the old stuff out...there seems to be sweet spots where the holes in the disc must align and then it passes through more...pics of what's inside would be helpful too....mines slowly freeing up but still a long way to go....need to try something other than turps I think...
 
If its not going to be opened, you'll probably lever to turn it by hand or a motor on it so that it agitates the insides and gets thinners into where they're needed.

Prob need to fill it with thinners, block the holes - then give it a good spin! Then see what comes out!
 
The way I see it. With 2 holes drilled opposite each other. Fit an air line to one hole and turn it to the top. The hole that is now at the bottom should allow the fluid out.
 
brake n clutch cleaner works !! just spray it in the hole ! turn the vcu with a spanner holding the other end still then let it drain , the solvent evaporates leaving the old fluid behind ,this can then be weighed to get the exact amount required to refill the vcu !
 
Update..

Ive got my vcu to the point I can now turn it with both hands....it has really freed up now...There is still old fluid coming out if I force air into it, but I may just leave it there....the turps substitute I was using works great..it combines with the fluid when mixed and seems to act like a lubricant....

Now I need to put something back into it.....initially I was thinking a 60,000 Cst...but I thinkbi will play it safe and go for a 30,000 Cst viscosity. ...I would like the vcu to be loose..I dont want any unwanted pressures on my ird/rear diff etc....its all going to be trial and error..but I have a feel of how I would like the vcu to preform now...hopefully I can judge this on the bench...as I know how it was and how it is now, so some where in between would be nice....

Any input welcome

:)
 
Think the trick will be getting the rear wheels to drive when needed ie when the fronts are slipping on soft ground. It could end up not kicking in at all and rendering you 2wd 😨😨😨😨
 
Yep that's the one.....but im pretty sure I can feel/judge this on the bench.....turning the vcu slowly and it goes round easily...speed up the rate of turn..and this is when the fluid starts to do its magic...and you start getting lock up.....

Will see what happens..
 
Well mate I wish you the best of luck... If it works then you can do mine to confirm the fix lol
 
With 50 plates in there, I wonder how much friction would be in there if a couple are sightly out of shape and touching? So the remaining friction may not just be the fluid left in there.

I suppose the resultant force your VCU will apply will depend on what grade fluid you put in and how much you fill it. You could do the workbech test before you put it on the car to calibrate it to a time X% faster than a working normal VCU would take.

If you are producing a 'soft' VCU this would presumably still help on road safety, but you would need to make sure that its was also capable of shifting the car on a 'muddy field'. If it were to just slip in that situation, I think it would soon destroy itself, or at least the fluid you've put in it. If you get it wrong, you might have been better off going 2WD now. Mind you there's quite a strong argument for the original VCU being like that !
 
i found when i did mine white spirit did the trick as it comes out with the silicon it evaporates so you can then measure how much to put back as to the silicon to buy i will try and find it if you are replacing with the 30000
nearly forgot i use compressed air to force the spirit in the vcu
there is listed maybe on this thread the amount you need for a refill and if memory serves me this will do 2 and a bit vcu's
Silicone Oil 30,000cst 30000 T3 Silikonol Syncro | eBay
or 3 bottles of this
[Team Associated] RC Parts Silicone Diff Fluid, 30K(30000cst) / 59ml (5457) | eBay
when i get the time i have another vcu to do but not urgent as i no longer have a free lander i went to the other side
hope it all goes well for those giving it a go
Ron
 
Just returned to this thread after stay in hospital ( new ankle). To find that two friends both engineers and both hippo owners after reading this thread have been very busy they have use of a commercial workshop and so have taken a different route.

They have split the VCU on a lathe removing the end cap. After dismantling and cleaning they have fine threaded the external body ,Then they have made from scratch a threaded retaining ring that holds it back together.
I understand that there were some problems that they seem to have overcome in notching the end cap to take an O ring + O rings in general Plus they are not happy with the grade of fluid there using and the amount. But they do have 2 test units fitted and on the road all ready.

I do wish they would allow me to post video they have made but as there looking to turn this modification into a commercial enterprise there holding there cards close.

Watch the net for announcments
 
Last edited:
Would adding valves so you can adjust air pressure to vcu have any effect on lockup and rate of slip etc?....you could vary the psi in the vcu to suit your needs. ...just a thought would it work?
 
bugsb said:
i found when i did mine white spirit did the trick as it comes out with the silicon it evaporates so you can then measure how much to put back as to the silicon to buy i will try and find it if you are replacing with the 30000
nearly forgot i use compressed air to force the spirit in the vcu
there is listed maybe on this thread the amount you need for a refill and if memory serves me this will do 2 and a bit vcu's
Silicone Oil 30,000cst 30000 T3 Silikonol Syncro | eBay
or 3 bottles of this
[Team Associated] RC Parts Silicone Diff Fluid, 30K(30000cst) / 59ml (5457) | eBay
when i get the time i have another vcu to do but not urgent as i no longer have a free lander i went to the other side
hope it all goes well for those giving it a go
Ron
Click to expand...
I used a turps substitute it says on the bottle...ingredients basically solvent...and yes it comes out nice mixes well too.....
 
GrumpyGel said:
With 50 plates in there, I wonder how much friction would be in there if a couple are sightly out of shape and touching? So the remaining friction may not just be the fluid left in there.

I suppose the resultant force your VCU will apply will depend on what grade fluid you put in and how much you fill it. You could do the workbech test before you put it on the car to calibrate it to a time X% faster than a working normal VCU would take.

If you are producing a 'soft' VCU this would presumably still help on road safety, but you would need to make sure that its was also capable of shifting the car on a 'muddy field'. If it were to just slip in that situation, I think it would soon destroy itself, or at least the fluid you've put in it. If you get it wrong, you might have been better off going 2WD now. Mind you there's quite a strong argument for the original VCU being like that !
Click to expand...
The plates are nearly touching each other from manufacturer..there is minimal clearance between them...less than a knats crack....:eek:
 
fredi250 said:
Just returned to this thread after stay in hospital ( new ankle). To find that two friends both engineers and both hippo owners after reading this thread have been very busy they have use of a commercial workshop and so have taken a different route.

They have split the VCU on a lathe removing the end cap. After dismantling and cleaning they have fine threaded the external body ,Then they have made from scratch a threaded retaining ring that holds it back together.
I understand that there were some problems that they seem to have overcome in notching the end cap to take an O ring + O rings in general Plus they are not happy with the grade of fluid there using and the amount. But they do have 2 test units fitted and on the road all ready.

I do wish they would allow me to post video they have made but as there looking to turn this modification into a commercial enterprise there holding there cards close.

Watch the net for announcments
Click to expand...
Sounds like what the vw lads have done on one of there sealed units http://forums.vwvortex.com/showthread.php?t=5958346

I escaped all this turmoil as I have haldex on mine :p

Tell them to let you post the video...other wise its all lies....:)
 
jedi said:
Would adding valves so you can adjust air pressure to vcu have any effect on lockup and rate of slip etc?....you could vary the psi in the vcu to suit your needs. ...just a thought would it work?
Click to expand...

I think it will be very difficult to adjust the air pressure inside a VCU because the volume is very small. Adjusting the fluid volume however is the efficient way to achieve the desired amount of slip/grip.
With a slightly soft VCU the TC will aid in getting traction. I am currently running one that is on the soft side and it works nicely for summer driving.
 
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