Cases of beer - you owe me :)

[QSHIPQ <QSHIPQ@aol.com>]

>1) scott, you base the *whole* of your case on btdt, and 1 sentence in the
>gleeson article (aka the 'weasle words' of section 5.2).  both jeff and i are
>attempting to get dialogue with the gleeson folks to clarify a hat-full of
>things, to fill in some of the blanks.
OK, sorry I jumped the gun, it's pretty clear to me.  Tshift happens, I don't
see much more that we need to clarify.  But sure, I'm just a goofball.  First
to admit it.

>2) your confident assertion that you are "arguing physics", and the rest of
us
>aren't is bollocks.  what you *have* done, is to present a case full of a
whole
l>ot of assumptions, none of which we can verify with science (aka
measurement,
>observation, replication).  your assumptions (from memory):
>. the behavour of a type 44/torsen executing under/over/understeer through a
>corner is explained by the behaviour of the torsen alone (i don't doubt that
>this happend btw, see below).
>. the centre torsen splits torque at the bias ratio when the car is
cornering.
>. slip angle is traction to a torsen centre diff 
>you also state that the gleeson paper is some sort of bible, where in
reality,
>it clearly says *very* little on the point on which we're arguing.  there are
a
>whole lot of things which are not covered, which we are attempting to get
>clarified (for instance, it spends only 1 paragraph covering the torsen in a
>centre diff application).
>some of your other assumptions (made quite confidently btw) have proved to be
>wrong before eg. because audi knew about the spider bite, they never raced,
or
>rallyed with the torsen centre.  they clearly did, and successfully, despite
>the 'physics' of the spider bite.
ER, ah, well, not exactly.  A torsen was used, was it 22/78/78/22?  Doubt you
want to argue that.  But that's what we got.  If you read, btw, the torsen in
terms of fwd/rwd you don't need to make any assumptions it's stated.  Slip
angle to both those configs is constant.  A variable in the center.  NO change
in design.  Implications, conclusions or jumps?


>3)you have *no* information on the implemetation of the torsen in the audi
>chassis.  you don't even know whether the implementation in the type 44 is
>*different* from the ur-q, the rs2, and the later cars.  do you?  it clearly
is
>btw, as the bias ratio has changed.  as you well know, most of the gleeson
>article is an attempt to model the theoritical basis of the operation of the
>diff, particluarly with regard the modelling of torque through the diff.  it
is
>not an explanation (and beleive me, i'd love one), of the operation of the
diff
>under cornering.  in the whole article, there is precious little about this
>thing which is the whole basis of the "spider bite".
Ur, ah no.  The torsen, is CLAIMED by audi to be 78/22/22/78.  The bias ratio
changed on the newest S4 (we only know half of it btw).  Documentation it
changed elsewhere?  NO.  In the grand schemothings it doesn't matter, if it
has a range that makes understeer and oversteer, the ratio is moot.  Torsen is
a traction device, that is all it is.  As stated in the article.  They don't
have to explain what it isn't.  If I were selling a couple hundred thousand
Torsen centers, my incentives to include what it isn't might be somewhat low,
don't you think?  Physics is physics.  Does it translate to real world, well
we can certainly say it CAN.  The rest is statistics until the model.


4>) your case, when studied, makes me wonder how my cars stay on the road at
>all.  the fact that they *do*, while doing the things i expect, indicates
that
>there are a number of *other* factors at play.  none of which we (me, you,
us)
>understand.  the fact is, and with your "spider bite" case in mind, both my
>cars have tracked truely without bite despite my best efforts at provocation
>(see previous posts of btdt).  btw, i've been sepnding the last week with the
>rs2 and gravel (coromandel) roads.  low traction, high intertial moments, and
>lots of fun (big time oversteer), but no bites (meaning, oversteer, back on
the
>power, back into line, lots of fun, and no drama).
Congrats, you are eliminating statistical non events, no physics OR no
specifics to the event, and no methodology to the non event.  Statistical non
events are only significant to the event with a correlation.  I can explain
your non event.  Can you explain my event?  Care to give the variables in the
matrix, might be a little more complicated than you are doing.  Or simpler.  I
haven't been struck by lightning either.  And I still don't stand under trees
in storms.  

>5) i'm not dis-regarding your btdt (in a type 44 w/torsen).  please respect
>others who have similar btdt (without the type 44).
>i do get annoyed when you claim the "physics" high ground, when all i've seen
>is a few formula based on the assumptions above, and *nothing* out of the
>gleeson paper.  btw, i've also posted formula which show that the torsen is
>much better than the locker when wheel lift occurs which, to me, is still
worst
>case....
Yup, you are correct, in a wheel lift scenario in a turn, the torsen is a good
absolute traction device, given and absolute traction problem, so posted and
agreed by me.  Before that is NOT worse case, by your own definition, and
that's when the spider bites.  The torsen paper explains rwd and fwd
extensively.  I don't draw any conclusions or assumptions that aren't already
there.  Sorry.  It's all in that paper.  You are not addressing the physics
only the effect of them on chassis dynamics.  That is a statistical event with
a lot of variables, that we haven't been able to put in a matrix.  Doesn't
change the physics of the event or the non-event.  Think about what you are
arguing first.

>one other nit, you keep telling us that a vc switches torque.  it does no
such
>thing.  it senses (switches) rotational speed.  you state that a (unnamed) vc
>can switch torque [sic] in "less than one revolution".  i'd love to hear more
>information on this?
Switches rotational speed, how do we measure that Dave?  IN terms of torque
transfer maybe, or am I missing something?  It switches torque based on speed
differential.  Maybe this will help your nit:

All Wheel Drive Performance Handbook, page 29-30.  Jay Lamm

"With the VC transmission, the viscous coupling doesn't merely oversee a
mechanical transfer system, it is the transfer system.  When the automobile is
travelling down a the road normally, axle speeds are relatively equal and
almost no TORQUE (reread torque here dave) is transmitted throught the
coupling.  If the primary drive axle starts to slip, however, the speed
differential between axles activates the viscous transmission and TORQUE is
quickly transmitted to the secondary axle.  This can happen in as little as
one-quarter rotation of the primary drive wheels."
Hello dave?  Did that help either of your 'nits'?

>lets continue this off-line, when we have more information..
>as i've said before scott, a beer awaits, and a couple of cars to drive
>whenever you make it to godzone...
Happy to.  And no offense intended or taken.  There is a plethora of mail in
my box, too that has coimbra on it.  This post should help you understand the
VC some too.  I believe to have the information I need, and happy to also
recind it.  I believe I also understand it.  And believe there is a lot of
MISunderstanding too.  Your keyboard just happens to be one of a few that
misunderstands.  No big deal.  Hey can you drive the 540i6?  I'd love to see a
comparo with the RS2.  

Scott Justusson