Re: torsen tech 101

["Rich, Jack" <JRich@Kronos.com>]

I can't believe I'm butting into the thread from hell, which I was really
quite tired of, but...

Dave,

When you refer to a "locker", are you talking about the Gen1 diff being run
locked, or unlocked?  If you are referring to unlocked, then it distributes
torque to the end of the car with the least traction.  This is a standard
differential, which I usually refer to as an "unlimited slip" differential.
If you are referring to locked, then I have to assert that this will force
the driveshaft to the front differential to spin at exactly the same speed
as the driveshaft to the rear differential.  Wheel slip is *forced* to occur
in a turn.

You say:
>when cornering within the bias ratio of torque distribution the torsen diff
>is *locked*.  you may need to re-read that statement.

Sorry, but re-reading it hasn't helped me.  You cannot say that a torsen is
*locked* in a turn within its bias ratio.  If this were so, it would not be
possible to turn a torsen-center-diff'd car at low speeds in a parking lot
without major drivetrain shudder and chatter as the wheels were forced to
slip.  (Never mind.  You can say it.  I mean that I don't understand it and
don't believe it.)  "Locked" means that there is no slip occurring, and that
the two outputs are spinning at the same speed.  I believe you may mean the
opposite -- that beyond the bias ratio (say 75:25) it "locks" into that
percentage, i.e. one output can never spin less than 1/3 the speed of the
other output drive shaft.  (I'm guessing at your meaning here.  I don't
claim to know poop from shoe polish about torsens.)

>let me say it again in a different form.  the torsen operates as a bevel
>differential until relative slip between the axles occurs.
There will be relative slip the instant you turn in a parking lot -- the
front wheels will be traveling a larger arc than the rear wheels.  The
output to the front diff must spin faster than the output to the rear
driveshaft.
>  this causes the
>differential to *lock*.
Gulp!  Can't be, unless a torsen Audi just practically *cannot* be turned in
a dry, paved parking lot.  I've made the mistake of turning off a snowy road
into a cleared parking lot with my center diff locked, and believe me, no
torsen is locked.
>  until torque distribution across the diff reaches
>the bias ratio.
This must be the part I don't understand what you mean, because hopefully it
refutes my understanding above.
>  which is usually 3:1 (25:75) in audi applications, but can
>also be 4:1 (80:20) depending upon the design.

I'm no expert on differentials.  My sole understanding is that they accept a
turning input, and convert that to one or two turning outputs (usually not
the output you wanted when it's only one of them.)  A locked diff converts
the turning input into two equally turning outputs.  (Am I wrong here?)
Your explanation of torsen hasn't enlightened me.  I think we must mean
different things by locked.

Another theory for Gary: People who drive on the left don't understand what
people who drive on the right mean, and vice versa. :^)  (This is a joke.)
(I personally like the theory that RHD and LHD models have different
balance.)

Jack Rich