RE: All the buzz about Diffy-q's

["Dave Eaton" <Dave.Eaton@clear.net.nz>]

nope scott, you just don't see it.  you're misunderstanding what torque is.
i'll say this one more time and then give it up as a waste of time, and
bandwidth...

torque doesn't (indeed cannot)  disappear in the ether.  with the locked
centre, the output shafts cannot speed up relative to each other, so torque
can and must transfer between them based on the tractive requirements of the
2 output shafts.  and in the case of a wagging front wheel, 100% (read that
again), *100%* of the torque goes to the back (less the frictional losses to
the front end).  not 50%!!!  torque cannot disappear.  once again, with a
locked centre 100% of torque can shift front and rear as and when required.

with the open differential and all wheels on the ground, 25% of the torque
is distributed to each axle.  regardless of the weight distribution (this
doesn't happen with a locked centre and all wheels on the ground, but until
you get the basics, there is no point in discussing that).  open
differentials reliably split 50% of the torque each way.  all the time.
even when one side has no traction.  when this happens, the diff will split
torque based on the tractive force of the *least* tractive output shaft.
the result, as orin has said, is the acceleration (increased speed) of the
lifted wheel.

i appreciate that this may be difficult for you, and that it is not what you
have understood, but if you sit down with a piece of paper and draw it out
it's quite obvious.  my offer for some spare time reading stands.  i can
even scan some stuff and send it to you if you'd like....

hth,
dave
'95 rs2
'90 ur-q
'61 mb fintail

-----Original Message-----

Date: Sun, 23 May 1999 22:02:07 EDT
From: QSHIPQ@aol.com
Subject: Re: All the buzz about Diffy-q's

Read Mr Eaton's post as stated again, Orin, maybe you'll see my point
better:
Dave E wrote:

> >the generation 1 locker *must* and does shift torque when it is *locked*.
> >(0%-100%-0% torque shift front to rear is certainly possible).

A locked center diff would have a maximum *torque shift* (please reread) of
50% not 100% as stated by Mr. E.  If you disconnect the driveshaft you only
have a maximum *torque shift* of 50% as well.  How exactly can we have a
0-100-0 *torque shift* in a locked center diff?  You can't.  My point.

>  This time, not much torque goes anywhere, excess torque produced by
>  the engine causes the engine, front driveshaft and left front axle
>  to accelerate - the wheel spins.

Ok Orin, reread Mr. E claims on open diffs here:
> >however, when all diffs are *open* *no* torque can be shifted.  all
torque
> >outputs are equal, and 25% by definition (for awd).

Unlocked, same lifting inside front wheel scenario....
All available torque shifts to the lifting front wheel, until spin that is
100% of engine torque, and by definition, once the wheel lifts is a *torque
shift* of 100% of available Trg (Torque ring gear).  Once lifted that would
be a *torque shift* of 100% not 0% as stated, even if engine total engine
Trg
output decreases.   Look at it this way, take an open diff quattro,  lift
one
wheel up on a jack, put the car in 1, let out the clutch out.  What happens?
The car goes nowhere, but the lifted wheel spins.  That is a maximum *torque
shift* of 100%.  You can't get any higher in *torque shift* or clearer in my
point.

Don't try the above trick with a locked center or a torsen.  Both will run
you over with a torque shift of less than 100%.  Always.  No thank you, I
haven't btdt...  :)

HTH

Scott Justusson
'87 5ktqwRS2 -10vt
'84 UrqRS2 -20vt
'87 4Runner turbo A/T