Re: Physics, Torsen

[ckuo@sprynet.com]

Scott,

I guess I still take issue with some of your terminology. 'Mechanics' would be a 
more accurate term than 'physics'. Torque shift is really a result of the 
mechanics of the Torsen. Physics does play a part in all of this, because the 
operation of the gears, bearings and other mechanicals is governed by the laws 
of physics, i.e. friction, opposing forces, inertia etc. However, the Torsen 
differential and its behavior was designed by mechanical engineers and designers 
using the mechanics of gear design and mechnical engineering design. -Just my 
engineering $0.02.

What I'd really like to know is, in your argument, are you stating that due to 
rear wheel slip angle alone, that maximum torque shift can occur?  I would agree 
maximum torque shift occurring in the middle of a turn could cause an 
interesting scenario. However, from reading the Gleason white paper, my 
impression is that it would take a significant loss in traction in either the 
front or back drivelines to cause a maximum torque shift. My understanding of 
Torsen mechanics is that torque shift is essentially instantaneous, and is 
infinitely proportional to the loss or gain of traction on a given output 
driveline. In fact, the statement 'Since division of torque is automatically 
achieved by the Torsen differential in proportion to available traction...' from 
the Gleason paper would seem to imply this. 

I guess that given a type 44 (and possibly anything else) cornering near the 
limits, it may not take that much torque shift to cause a variation in the 
chassis dynamics. Whether the variations are good or bad is another question, 
and that could depend on the driver. One aspect that could be investigated is 
whether or not there is some resonant frequency or oscillatory mode of the 
Torsen-drivetrain-chassis system which could cause problems. Since Urqs and type 
44s have significant different dynamics, and different tires and suspension 
tweeks can have different dynamics, perhaps this could explain why some people 
experience the bite and others don't.

If I'm just repeating stuff already discussed on this thread, my apologies to 
the list.
Just being a curious observer...

Chauncey Kuo
ckuo@sprynet.com

85 5KS Avant
84 Scirocco II
Rossignol Extreme monoski - the ultimate cornering machine