Every time this comes up, it gets more aggravating.  I'm no mechanical
engineer, nor am I a chemical genius or silicone fluid professional, I
don't even own a Syncro . . . yet.

However it all seems very simple to me.  A Viscous Coupling is a COUPLING,
not a differential.  A DIFFERENTIAL PROVIDES SLIP UNDER LOAD (ie cornering)
A VISCOUS COUPLING LOCKS UP UNDER LOAD AND provides SLIP under NORMAL
CONDITIONS.  The two are completely opposite.

The VC in a Syncro takes the place of a transfer case does it not?  It
allows you to drive in 2wd when appropriate, then mechanically engages the
front drive, without actually having to engage gears in a gearbox.  It
also, because it is fluid, reduces wear on the drivetrain (gears don't
"give").  I see no differential action taking place here and I don't see
why everyone keeps bringing it up.

If the silicone fluid had exactly opposite properties, and would lock a VC
under normal conditions, providing limited slip under stress, then it would
have application in a differential set up.  This may be what the Jeep/Talon
setup actually does. . .?

How often have any of you Syncro owners had to change a VC?  Is it often
enough that it makes it not worthwhile owning one?  I am currently looking
at an 86 Syncro that I can probably get for about $3500 (canadian), but if
I am going to have to spend that much again in 3 months when things start
getting muddy (glorious mud :~) ) to replace a VC, or go on the never
ending search for silicone fluid, then whats the use?  If there was a
source for the fluid in North America, then wouldn't a car company have a
vehicle out that uses a Viscous Coupling? (NOT a viscous DIFFERENTIAL)  I
think that one of our european listees could probably find some. . . At
over $3000 a piece, a couple of us could get together and pay for a nice
North American vaction for Helmut, providing he brings over a couple of
gallons of silicone fluid. . .

Gary Thaxter
74 transporter (panel)
85 transporter (kombi?)
looking at an 86 syncro and now a 91 cargo van

Anyone know what kind of setup the Subaru uses?  What about the "electronic
4wd" you see on ford aerostars and such?  What about the 400hp porsche
AWD??