RE: open diffs at the limit.

[David Eaton <david.eaton@computerland.co.nz>]

so orin, you are saying that that locked cntre diff is actually *worse*
than the torsen because it can modulate 100% of the torque from one axle
to the other in the wheel lift sceanrio?

eg: front wheel lift, 100% of torque to the rear axle courtesy of the
locked centre, once front wheel traction is back (later in the turn),
bang, and you've lost 50% to the rear, and have it back at the front.

again, the torsen has better behaviour than this because t(shift)
[=t(max) - t(min)] is less.

agree that the open centre can be a very dangerous boris...

dave
'95 rs2
'90 ur-q
> 
>-----Original Message-----
>NO.  Again, locked diff can send 100% to one axle if it has the
>grip.  Think about this... with a locked diff, one axle with
>no grip (imagine wheel in the air), the axle with no grip
>becomes no more than a useless appendage to the other shaft.
>Take a pencil, one with an eraser on the end.  Grip it in
>the middle.  Put the eraser end on a reasonably grippy surface.
>Turn the pencil as if it is an axle and the eraser a wheel.
>All the torque you apply to the center of the pencil is
>obviously going to the eraser end, the other is just flapping
>around in the air doing nothing.  Add some bearings, you
>have to overcome the friction of the bearings, that's all.
>
>A LOCKED DIFF CAN TRANSFER 100% OF INPUT TORQUE MINUS BEARING
>FRICTION TO ONE AXLE!!!
>
>BTW, torque, cannot be 'lost'.  If input torque to the system
>as a whole exceeds output torque + plus frictional losses,
>then the whole drive train accelerates at a rate proportional
>to excess torque divided by the moment of inertia of the
>whole system.
>
>It is the OPEN diff that gives a 50/50 output distribution...
>and it is CONTROLLED by the output with LEAST traction...
>open diff, one wheel on slippy surface, only twice traction
>at slippy surface transferred, excess torque accelerates
>drivetrain and wheel, ie the wheel on the slippy surface
>spins along with the drivetrain.  Sorry to say it, but that's
>the physics of the matter.
>
>Orin.