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Re: Torsen + EDL

In a message dated 98-03-04 11:25:59 EST, you write:

<< You didn't understand my statement. Let's try again.
> I _think_ (somebody correct me if I'm wrong) that EDL works as 
> two separate systems: one front EDL, and one rear EDL. All it sees 
> is differences between left and right wheel speed at one end of the 
> car (front or rear). If EDL was looking at the bigger picture (trying 
> to balance wheel speeds left to right, front to rear, and corner to 
 >corner) then there would be no need for the TORSEN center. It 
 >would be redundant. 
 I don't think your assumption to be correct.  Since EDL is Electronic Locking
Differential, I presume front to rear to be controlled.  If what you say is
true, then EDL has NO effect or control on the torsen, once the slip angle is
high enough, specifically, you can still get 100% Tshift with no wheel lift.
If that Tshift creates a spinning wheel, EDL will regulate that.  I still
don't see that as a correction.  40kph is not really the issue, regardless, so
I don't think we need to look at this too hard.  But as always, happy to.
 >By the same definition of a torsen center, as soon asyou turn, slip 
 >angle to the torsen becomes a variable.  INTERPRETED as a 
 >traction.  That's the problem.  4 Wheel EDL doesn't change that.  
>> Maybe not, but 2 wheel EDL will affect which wheel on the front 
>> gets the torque and which one on the back gets torque. By effectively 
>> locking the front and/or rear diffs when spin-up occurs, EDL 
 >>definitely changes how the TORSEN reacts in your "bite" scenario. I 
 >>realize you wanted to hold off on the EDL discussion until the gen II 
>> was sorted out, so we don't have to go any further into this. I'd still 
>> like to know what Boris does when the rear diff is locked on the 
>> gen II, though.
That really doesn't change the Tshift, only addresses Tshift to traction.  My
scenario is a pretraction problem in terms of the center torsen.  Trg to the
ground can be 100%, and Tshift can be maximum.  When you lose traction Trg to
the ground reduces, but it does that without EDL as well.  What you are
indicating is that EDL will prevent the Tshift from spinniing the front or
rear wheels.  That is really presenting a Torsen Center + Torsen Rear VS.
Torsen Center + EDL  VS. Torsen Center + open rear argument.  Not disagreeing
with you necessarily.  We just aren't there yet, in more ways than the
obvious.  Remember tho, I haven't lifted a wheel yet.  AND I've Tshifted
150lb/ft of torque.  You are addressing that in terms of lift, same issue as
Dave E.  I'm NOT.  
 >>BTW, as for the TORSEN extrapolating traction from driveshaft 
 >>speed, I'm not convinced. The Gleason tech paper seems to imply 
 >>that it's reacting to frictional resistance rather than speed 
>> differences. I could be wrong, though. Maybe one of our MEs 
>> should have a chat with them?
Frictional speed to a front torsen or a rear torsen is traction, since Slip
Angle in relation to traction is a constant (both tires have the same slip,
torsen will operate on traction alone).  Since a torsen center operates on
what happens to the front and rear driveshafts, friction CAN be Slip Angle, as
well as, traction.  Either or, or both.  The torsen interprets them as the
same thing.  Traction spins a rear wheel, rear driveshaft spins faster than
the front, torque is sent to the front.  Slip angle slows the rear driveshaft,
Torsen believes that front to rear slip angle to be a FRONT TRACTION problem,
and Tshifts to the rear.  You may or may not have a front traction problem is
exactly my point.  


Scott Justusson