RE: torsen naderism

[audidudi@mindspring.com (Jeffrey J. Goggin)]

>this seems beyond simple.  you state that the torsen just takes input
>torque and spreads it around.

Yep, that's it.  Nothing more, nothing less.  It's a dumb device and cannot
respond in any other way except as pre-programmed by its designers.  It
doesn't know if it's allocating torque between the front and rear wheels,
the left and right rear wheel or the left and right front wheel ... to the
Torsen itself, they are all one and the same. 

>apart from the different torsen designs which audi used (which you seem to
ignore;
>my rs2 uses a different torsen than my ur-q for example), and the
simplistic assumption that all
>torsens are the same (clearly they're not, as a simple visit to the
>zexel web site would show).  anyway, apart from these things i agree.
>that is siple and obvious.

All Torsens used by Audi in a center diff application ARE of the same basic
design and, so far as I can tell, of roughly the same bias ratio.  That's
pretty much all you need to know to determine how the Torsen operates ...
which, of course, may or may not tell you anything about how the car
equipped with a Torsen behaves while being driven at or near the limits of
adhesion.  

>but what beggars belief is that you then state that this proves that the
>"bite" *must* happen on all chassis, because of it's alleged occurance
>on a type 44 chassis.

If you accept the basic principle of operation, then it's a given.  Like I
said, what happens to the car AS A RESULT OF THE TORSEN's operation is
another matter altogether.  Some cars may handle this better than others;
some cars may not be affected at all.

>so, you assert that the the following have *no* influence on the
>torsen's input parameters:
>
>1) the ability of the chassis to put power to the ground (and keep it
>there).
>2) the ability of the chassis to provide good levels of steering
>response when cornering
>3) the roll stiffness of the chassis (keeping tyre contact patches on
>the ground)
>4) the type and quality of tyre used
>5) the fundamental dimensions of the chassis (wheelbase, track etc).
>6) the torque characteristics of the engine

All of the above parameters may indeed affect the INPUT signals from which
the Torsen takes its lead; however, NONE of them will alter how THE TORSEN
ITSELF operates.  Give it the same set of input signals (as modified by the
above factors in whatever combination you prefer) and it'll allocate torque
exactly the same way ... every time, without exception.  Like I've said,
there's no way that it CAN'T do this.  It's just a simple mechanical device
-- dumb, even -- that's remarkably complicated to design.

>and then you assert that a visit to steamboat is required to "really
>show the bite" ie. in a low cf environment.

It's not required but the easiest way to do so ... convincing you has been
difficult enough as it is, why make things any more so?  Like I said, I can
do it on dry pavement (pretty much on demand now, thanks to practice!) but
it takes just that much more effort because the threshold is just that much
higher.

>reality check brothers.  on all of the above 6 points, the zexel
>engineers disagree with you.  hell, what would they know...

Be careful here, Dave.  They DON'T disagree with me, at least so far as the
basic operation of the Torsen is concerned.  Each of those factors will
modify the input signal to a different extent and Yes, if your goal's
optimizing the design/specs of the Torsen to a particular application, they
must be taken into account.  But they have no effect whatsoever -- repeat,
NO EFFECT WHATSOEVER -- upon how the Torsen itself operates.  QED.

>for all we know, it's the *inability* of the type 44 chassis to do some
>of the above things "consistently" which produces the bite, where it is
>simply non-existant on other, better balanced, chassis.

Quite possibly ... but it's also possible that the Type 44 is a superior
chassis design and thereby responds more immediately to any changes in
torque distribution.  At this point, though, I can't tell you which and I
have never claimed anything other than that the Type 44 and Torsen
combination isn't a particularly good one ... it's entirely possible that
the RS2 and Ur-Q chassis cope with a Torsen doing its thing much better than
any of Audi's other chassis.  Personally, I think this rather unlikely in
the case of the Ur-Q -- after all, its chassis was designed well before Audi
ever considered using a Torsen whereas the Type 44 was very likely designed
with the Torsen in mind from the outset -- but I acknowledge that it's possible.

That said, the basic design of the Torsen CANNOT guarantee that it won't
someday allocate torque incorrectly and/or inappropriately between the front
and rear wheels of whatever chassis it's installed in.  Whether you will
ever experience this personally and if so, whether it will upset the
handling of the car you're driving isn't something I can predict.  However,
like it or not, I can say unequivocally that the *potential* for it
happening is part-and-parcel to the Torsen's basic design and inherent in
ANY car that is equipped with one.
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   / |      _| o    | \       _| o  Jeffrey Goggin
  /__| | | / | | __ |  | | | / | |  audidudi@mindspring.com
 /   | |_| \_| |    |_/  |_| \_| |  http://www.mindspring.com/~audidudi/
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