If you ever wondered what was inside the VC

Post by **Aidan** » 17 Jun 2007, 21:36

I need a VW 3136 tool so I can do bearing replacements on front diffs as well as rebuilding gearboxes, but the tool is no longer available, and after six months of trawling the world's ebay sites, vw forums and sites, and even speaking bad german on the phone to a very nice man at the original tool makers and getting nada I decided the time had come to strip my spare, spare, tight, VC for it's inner axle to make my own tool....and hey it worked, I have welded a suitable socket to the axle and now have the ability to undo the speedo-drive/pinion bearing lockring, and more importantly do it up to the correct torque when replacing the bearing, so all good

I took some photos whilst I was at it and have quickly put together a little site with them on for you to enjoy.

http://homepage.ntlworld.com/aidan.talbot/VC/index.html

Post by **Simon Baxter** » 17 Jun 2007, 21:46

Too simple, and begs the rebuild question..

Post by **andysimpson** » 17 Jun 2007, 21:56

Simon Baxter wrote:Too simple, and begs the rebuild question..

I was thinking the same.

Post by **Aidan** » 17 Jun 2007, 21:58

all we need is some fluid and a fill quantity and a trial vehicle, oh look there's one parked outside

oh and a source for the oil seals and o ring too

there was a little scoring on a couple of the discs on this one, but it seems to be a design thing that the two outer discs have no spacer so they get hot quickly

Post by **peasant** » 17 Jun 2007, 22:04

veeery interesting !

Can't really see any reason why anything metal in there should fail substantially and/or terminally.

On most failed ones it has to be just a case of old fluid and maybe a cracked seal ?

Post by **oorwullie** » 18 Jun 2007, 08:08

fascinating stuff.doesn't look very complex!

Post by **Hacksawbob** » 18 Jun 2007, 09:15

Nice one Aiden, Fascinating stuff, you are venturing where no syncronaut has been before (as far as I'm aware) SOOOO whatcha gonna put in it? any old silicone? would you need to fill between each plate as you put them in? I suppose would depend on viscosity of the stuff in its "resting state"

Post by **HarryMann** » 18 Jun 2007, 09:47

Great exploits and photo-article Aidan, opens up a whole new world -

fascinating stuff. Doesn't look very complex!

Hehe! No doesn't, does it!

The simplicity of its construction belies the complexity of hydro and thermodynamics going on there... which is why it's such a fascinating device.
It took quite a few years to find the trick to getting these things to act as an auto-lock clutch in a controlled and predictable way. Without the slots and holes and other clever tricks, you just get a steadily decreasing torque Vs speed curve as fluid viscosity, even silicone fluid, decreases in the normal way with temperature - quite the opposite of what you really need.
These things work at transient internal pressures up to 100 bar and the plates deform in 'sets' and pairs. The fluid 'fill' is quite critical, in viscosity and volume terms. Too much and it'll burst, too little and it won't lock early enough - and then might overheat.
The working analysis has been advanced a lot in the last decade and is now pretty well understood, though is still a mixed mathematical 'model' based both on theory and empirical correlation, giving a way of scaling and designing couplings for a variety of sizes, loads and speeds.
More advanced viscous couplings now have servo-control of locking behaviour - quite a long way from the original Ferguson/Rolt patents.

Post by **KarlT** » 18 Jun 2007, 09:48

I've got a couple of tubes left over from doing my bathroom if thats any good to you!

Post by **HarryMann** » 18 Jun 2007, 09:53

Breast enhancement silicone might be a bit more suitable... if you could make some of that available

Post by **syncroand101** » 18 Jun 2007, 09:58

p.s.. nice write-up Aidan.

Lets go organic and use Cornflower mixture, that goes nice and thick when stirred...

Post by **peasant** » 18 Jun 2007, 10:43

according to these guys
http://ig-syncro16.de/dragonfly/index.p ... ht=Silicon

Its somewhere between 265g (for a 14") and 290g (for a mainly offroad 16") of "Wacker Siliconoel AK 90000"

Where to get it though is the difficult bit.

Post by **syncroand101** » 18 Jun 2007, 10:47

I thought it was a Silicone patented by SDP. And only available through SDP in Barrels. I think this was the case when I looked at it about 5-6 years ago!

Post by **vwjon** » 18 Jun 2007, 11:13

if its only avaliable in barrels, why not get one then sell it off in 290ml bottles to the madding crowd! put me down for two, poss three, and i'm sure there will be a few more ozzy's interested! (postage?) cheers jon

Post by **v-lux** » 18 Jun 2007, 11:27

Hell

i'll have a bottle of that too!!