t differences

[QSHIPQ <QSHIPQ@aol.com>]

Stilian Elenkov writes:
>As far as I know VC does not work very well while braking (I mean it
>really sucks).
I'm guessing late entry to the whole thread Stilian.  I might direct you to
the 90 vs 90q 11/88 for some insight as to torsens under braking.  Be careful
saying this, the only words in that web page are that they are locked.  So are
torsens.  We aren't to this point yet in the discussion.  Some agreement on
acceleration might be in order first, don't you think?  Ck the archives...

>Try breaking into a corner with both rear wheels locked in sync cos the
>VC sensed some Rotational
>difference. Is that a good thing.

Are you going to tell me that a worm gear is freewheeling?  Read the following
in 'great detail' first to get up to "speed" here:
http://www.mindspring.com/~audidudi/Torsen.htm

Neither a VC or a torsen does well in braking.  Why?  Cuz both are linked
while stopping.  One bettern' tother?  Both have BR, with minimal Trg.  The
point gets washed.  We haven't come to a consensus on torque yet, and you
already want to argue the braking equation?
 
>I do not buy that at all. Torsen has proven to be very competitive in
>racing  - Look at Lancia Delta and the UrQ that use Torsen vs the
>competition using VC.  If torsen was so bad nobody would use it
>considering it is more expensive. Also VC has logarithmic action and is
>greatly affected by temperature. Imagine an exhaust leak close to the
>rear diff and constant lock - now that will be pretty in turns.

You are reciting the incomplete web page you referenced.  Read the archives to
get some better background, this is a rehash.  Torsen in 78/22/22/78 hasn't
"proven" anything at all.  IN fact, you can't argue that it was used in ANY
quattro (and btw, the Urq NEVER used the torsen in racing, only the S1).  More
expensive for a dumb device, don't make it better.  VC is just as dumb, don't
give it a logarithmic action.   Be careful with blanket statements of temp and
viscosity.  VC's have become very refined of late, for dumb devices. Remember,
ONLY if you change inherent chassis dynamics in a turn is a VC a *bad* thing.
O-O-O in a turn at WOT with a VC split at 65/35 is not ugly sir.  A U-O-U in a
turn with a torsen is.

>Torsen does not detect slip (which is rotational difference) that is the
>job of VC
Er, well, correct it doesn't detect slip, cuz it considers it a constant, even
though its a variable.  However, slip is designed into both switches, or you
can't turn without distributing torque.  Old post.  Wrong on either
intentional definition.  

>after the slip has occurred ( ~ 0.5 - 1.0) seconds AFTER the slip
>depending on the 
>setup for racing apps sometimes even later.
NO.  That is not a time lock, it is a rotational lock.  The latest and
greatest within less than one revolution of driveshaft.  .5 seconds is a long
time.  Remember driveshaft slip is NOT a spinning wheel necessarily.  

> Torsen does not allow
>"theoretically" the slip to 
>occur while allowing rotational differences during braking and
>cornering. That is what the Torsen white paper states. If you do not
>agree with it prove their data wrong with good enough sample pool
>(statistically significant). Chassis dynamics is all nice and pleasant,
>but VC offers more disadvantages than torsen according to european
>racing statistics (results I mean).

Again archive search.  You are way behind here.  There is a bias ratio on
braking in a torsen, it doesn't freewheel.  You need to really look at the
device sir.  A torsen cannot tell if a tire is slipping or losing traction.
To the input, the torsen assumes both to be the same.  It is a dumb device,
don't make it smart, it's not.  "Which european racing statistics" do you
refer to?  We all musta missed something.  Chassis dynamics is NOT all nice
and pleasant, cuz a torsen doesn't know them as anything but traction inputs.
Slip angle and relative slip angle are NOT traction inputs.  Torsen fooled. 

> 
>The page  http://www.rallycars.com/Cars/4wd_turbo_cars.html  that I
>pointed you to has a lot of links proving that racing cars using torsens
>are winning vs VC equipped competitors, now if that is not good enough
>proof that torsen works in 10/10th I do not know what is. BTCC A4q,
>rally UrQ, and Lancia Delta are some of the prime examples of cars that
>dominated while using torsens. Now that is a fact, that no chassis
>dynamics and slip angels can argue with. Torsen might have some
>weaknesses, but none of the above mentioned teams complained about it,
>and honestly I do trust their experience most. If you detest torsen so
>much why do you drive a torsen car? Get a Subaru WRX, I hear they are
>great cars.
Again you are way behind here.  Rallycars.com gives a very simplistic and
mostly incorrect synopsis of torsen and vc differentials.  The Urq never used
a torsen, so nix that.  The BTCC A4q, you may want to ck your stats, or Phil's
interesting observation looking under one.  Regarding the Delta, what was the
torque split on the torsen, do you know?  If you read the literature, the
Delta ran 56r/44 front in the early cars and 57r/43f on the latter cars.  Both
were inherent neutral to oversteer torsens.  A wee bit different than the
78/22/22/78 U-O-U torsens audi enjoys.  

BTW, if you read the archives, you will know that I don't OWN torsen cars.  I
own 3 locker quattros thank you.  Before you get all worked up, catch up to
the discussion in archives.  You are way behind, and premature in the firing
of the Torsen Patriots.

Stilian, I think you are late to bloom here, and way underinformed.  Before
you fire butane you may want to ck the archives to make sure you are not
slaying way dead horses.  

Just a thought, from one who claims nothing.

Scott Justusson
'87 5ktqwRS2
'86 5ktqw
'84 Urq