Re: A couple thoughts

[PDQSHIP@aol.com]

In a message dated 96-01-12 13:35:35 EST, you write:

>the clutches are exactly what the name implies: clutches.  they work
>by friction surfaces rubbing against each other.  the clutches are
>pressed together with hydraulic pistons, which are in turn
>electronically controlled, with inputs coming from wheel sensors,
>accelerometers and the brake pedal (for deactivation).  without
>the electronics, the clutches have no capability of locking.  and
>that's the failure mode.  a free unlocked center diff.

Unlike clutches in the traditional sense of an LSD, the clutches aren't what
the name implies on the v8, they are used more for allowing slip (as in a low
traction turn) than generating heat to "perform" as in an LSD.....  Look at
it this way eliot, the hydraulics make the diff either lock or unlock, not
progressive, not wear-tearing, heat generating progressively applied, as in a
true clutch or LSD.....   What their primary function is on the v8 is open
when no hydraulics, and allowing some "slip" while turning with "hydraulics"
activated......  The activation is a clear and precise on off function, the
clutches only allow for slip...   The 959 (page 126-7 of your reference
material) used a progressive clutch arrangement that can be considered a
"smart" system.....
>
>the viscous coupling relies on the shearing of a viscous oil by discs
>with cutouts to transmit power.  there is usually no contact but they
>can be made to rub under extreme conditions if desired.  it is much
>much simpler (and dumber) and has nothing in common conceptually with
>the clutches.  there are no electronics involved in the heart of the
>VC.

However, and this isn't in Lamm's book, the VC has progressed beyond the
"smart" stages of your v8 system, in that there are no "clutches" to slip to
make a turn.....
You may want to read up on the advances made in VC beyond Lamm's 1990 publish
date....  Either Porsche or Mitsubishi has that information available to
you.....

Scott