Viscous coupling silicon

[sandwedge]

Found this for anyone thats interested http://www.dieselkontor.de/product_info ... ts_id=3022" onclick="window.open(this.href);return false;

[KarlT]

Now that is interesting.
Next question is.....Does it come with instructions?
How hard can it be?
Can anyone find info on someone using this?
My VC is a tad tight, & at new units now costing 900euros, this has got to be worth a look!

[syncropaddy]

Now that is interesting.
Next question is.....Does it come with instructions?
How hard can it be?
Can anyone find info on someone using this?
My VC is a tad tight, & at new units now costing 900euros, this has got to be worth a look!

Yes it is
I doubt it very much
Very .... ask Aidan
Ask Aidan
If your VC is tight buy the recon one that Aidan has for sale

Buying the fluid is only half the job ..........

[KarlT]

Hmmmmm....Was hoping not to spend £500 though!!
If 63 euros is half the job I'll be happy!
Will look a little deeper into this. Any more advice welcome.

[syncropaddy]

Well Aidan tried it and he still gets his from the guy in Switzerland ........ nuff said!

[peasant]

Several people on the German IG16" forum tried a DIY refill and the results vary widely. There seem to be minor differences internally (wear mostly) between VC bodies and so the amount of silicone that worked for one didn't work for the other etc. Also, apparantly minute differences in the amount of silicone make for a huge difference in performance character. Another issue seems to be that the refill silicone doesn't have quite the same characteristics as the original stuff. So weighing/measuring how much comes out and putting in the exact same amount of new stuff apparently doesn't work either.

The main problem is that you can't test your VC other than by driving it ...by the time you finally get it right you might have had it in and out and filled and re-filled several times.

I've just fitted a refurb (from the Swiss guy via Busschmiede) or rather I've had it fitted. That works perfectly, cost 400 and something Euro and was done in a day (and it came with a test protocol)

[Aidan]

I looked into this and decided that without the test equipment and a proper procedure and without pressure filling equipment I could not do it with any guarantee of success so I'd rather get them from Dorfbrunnen, who has done 800 of the things, has all the gear, spare plates and cases and centre axles and the correct seals and offers a 12 month guarantee and the paperwork to back up the work. It does mean dealing with Dorfbrunnen though Or you can source from Buschmeide or Syncroservices.

There's a guy in the french club who does home rebuilds, but most of them run decouplers so a bit stiff (sports if you like) isn't a problem. I couldn't find anyone who could give a precise weight, or measure for the fluid and having taken one apart I know you can't just pour it in. Jake found a source for the correct fluid but it was 50l itres minimum I think and no information on coshh, storage and shelf life.

But please don't let me put someone off from having a go themselves, if you can do it for less than a hundred quid then great eh.

[sandwedge]

I was thinking, if VW VC are so expensive, is there a cheaper alternative that could be incorporated into a modified propshaft.

I.e. use a solid shaft in the diff and mount and external VC from a freelander or similar, or would this throw the balance of the prop out, and I guess the VC is tuned to the drive train.

[..lee..]

cant see why an external vc and solid shaft wouldn`t work if done right.

ok we know about testing the vc by driving but i`m suprised there is not specific torque vs temperature readings that can be used to test the vc in the workshop.

[HarryMann]

ok we know about testing the vc by driving but i`m suprised there is not specific torque vs temperature readings that can be used to test the vc in the workshop.

There is, of course... since day 1 rapid production quality test done with a temperature~torquemeter at about 75 rpm

This has all be discussed many times in various forums, specifically syncro.sa about 2 years ago in depth and here now again


From our own Syncro website, images been there about 5 years now..



This is what would be needed as a minimum for calibration.. a torque/temperature calibration test-rig (lathe type device with a torquemeter) Dorbrunnen acquired SDPs

NB. The above is a production calibration curve, that's all. It is not one of a whole set of VC design/optimisation/performance paramaters for VCs, so cannot directly be used to determine VC behaviour - just the easiest way to tell if the VC is 'within spec'

Without disassembling and cleaning the plates of a VC, it would be quite difficult to to get the fill volume within an acceptable range. The important parameter is the post-fill void volume, % wise. It has to be quite accurate, as pressures can go above design max (100 bar) otherwise, or the VC slip permanently. New main seals would be a good idea too (100 bar pressures!). Also bad ones can have plate surface wear.

Void volume (%) varies with siloxane viscosity. Some people know the original viscosity used, but these fluids have been under constant development, many now contain performance/anti-ageing additives that probably weren't in the originals.

[HarryMann]

Additional...

Dimethicone is another name for polydimethylsiloxane and is used to impart a soft velvety feel to hair or skin products. It is also used as an emulsifier for "water-in-oil" emulsions.



Note: Doesn't quote the actual viscosity (in CentiPoise) just 100.000 specification

Looks like it comes from USA and sold principally for cosmetic/medicinal uses

===

Ah! ..a nd a bad one as received at Dorfbrunnen

[sandwedge]

Just spent the last hour reading through all the links on VC's, I would conclude that its defiantly not a job that can be done at home

Unless you have a fully equipped test facility, and all the specialist kit required.

Which is a pisser, as my VC is presenting symptoms of being on the way out, and its apparently new, fitted to a rebuilt diff in May 2009, guess previous owner may have given Adrian a second hand VC.

Just to check VC is not supposed to stop forward movement on full lock low speed maneuvering is it?
If Im turning on full lock its like the front brakes are on, it can be overcome by using the accelerator, Im guessing this is not normal. Any other sort of driving it seems fine.

[HarryMann]

No that's quite common.. don't panic Captain Mannering

After all, full lock on any car takes a lot of force to scrub the wheels (they're not on rails are they, the pushing sideways, scrubbing)

Then there's the fact that the 'full' lock on a T25 is pretty tight by any standards. And then it's a 2 ton van

A whiff of gas is of course required to push it around - but really - don't use 'absolutely' full lock unless you 'absolutely' need to... eh?

Chances are, unless it stiffens up a lot when it's hot, after a long run at heavy load, it's OK. They're often a bit stiff when cold, by design.

Seriously...

===

I guess sooner or later we should set to and try to make a crude calibration rig, to at least check them... chances are quite a few that go back to Dorfbrunnen are still within spec. or not too bad. A bit like half the T25 starter motors that GSF take back as exchange (I'm told)

[sandwedge]

Cheers Harry

Just not used to a 4wd feeling like that at low speeds, then again most of the 4wd vehicles Ive driven over the last few years have used the VW 4 motion system not a VC.

[HarryMann]

then again most of the 4wd vehicles Ive driven over the last few years have used the VW 4 motion system not a VC.

Do they turn as tight? Were they manual or automatic? 2 tons?

The VC is a compromise, but a good one IMO