RE: VC vs awd

["Dave Eaton" <Dave.Eaton@clear.net.nz>]

whoa scott!  pull up!  think about what you have just said...

scott: "Toyotas system for example, uses an open diff center differential
that transmits power equally to both front and rear driveshafts (effectively
an open center diff awd).  When slip occurs, the VC coupling effectively
locks the center and rear drivshafts (think of it being "around" the center
diff)"

simple question here scott.  how can the centre differential distribute
power equally both front and rear *through* the vc, when slip has not
occurred?

you should know that a vc does not start to lock *until* slip has occurred.
therefore, in the normal mode (equal traction, no turns), there is *no*
slip, *no* vc lock, and ipso facto *no* drive through the vc.  that equals
2wd.  when slip occurs (cornering for instance), then you have 4wd.  it's
still "full-time awd" as far as the marketers are concerned, just not as we
know it.  ditto the haldex.  you just bought the marketing spin without
thinking :-)

you need to understand how a vc works.  because the vc is a friction device,
it cannot sustain long periods of lock (hump) without damage (heat).

fwiw, there is a comprehensive discussion of these issues in the paper "a vc
in the drive train of an awd vehicle" sae #860386.

dave
'95 rs2
'90 ur-q
'88 mb 2.3-16


-----Original Message-----

Date: Thu, 23 Sep 1999 08:50:54 EDT
From: QSHIPQ@aol.com
Subject: RE:  VC vs awd

Dave, this concept has eluded you for some time.  VC with Center Diffs are
rather easy to be full time awd.
[snip]
I'm surprised with all your white paper, this awd concept eludes you.

HTH clear up the confusion you raised.

Scott