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RE: RE: Torsen 201

Car 80q fully loaded, hi cf, 45m radius, accel 4m/s

According to 885140 this car will cause a torque dist of 38f/62r.  Let's call 
this an O dynamic chassis.  As you add acceleration (increase trg or lower 
cf) you can cause the rears to break loose from traction argument.  As soon 
as they do (and forced slip is irrelevent = 'torsen 103/201', cuz as you 
allocate torque from rear forward you are back into the range of the torque 
split), torque is shifted forward to avoid spinning the rear wheels (or if 
you are already accomodating rotation -see below, the rears will spin before 
torque shifts). The shift will be at the BR, which causes 75f/25r = U.  
However, since you have done nothing to the steering input, the relative slip 
angles will dictate that 62r/38f is the dynamic condition with no traction 
issues.  So, after U, and now rear traction is restored, slip angle 
differences put you "back" to O (62/38).  Doing nothing else, this will cycle 
indefinitely.  Enter the driver.

When U occurs, the front end will now deviate from the apex outward, which 
would require more steering input (we can discount throttle input as an 
option or we wouldn't be here to begin with:).  As you steer into the apex 
more, 2 things happen.  You have now a default slip angle difference higher 
than your initial turn in.  This will cause another torque allocation to the 
rear at a higher rate, which causes another traction argument, which causes 
another shift to the front = U.  

The real torsen issue is where the threshold for U and O are in a given 
chassis with a given load at a given acceleration on a given surface in a 
given radius.  These are not constants.  So by definition, neither is the 
point where slip angle differences or traction inputs rule chassis dynamics.  
The "accomodation of different speeds of rotation", although a valid 
argument, is confusing.  This scenario would require a very small radius 
turn, where all dynamics are most likely irrelevent, or put another way, what 
speed did you hope to go thru a 15m turn?  So one could easily argue forcing 
differing speeds of rotation isn't relevent to the bite due to slip angle, 
cuz you just can't drive fast enought to make it relevent.  Try it, put the 
wheel at full lock, what's the fastest speed you can travel in a 15m circle?

I'm getting confused with the presentation Dave.  It is introducing 
irrelevent (or unrealistic) variables into the discussion.  Let's stick with 
*just* what the torsen does or doesn't do for now, it's easier.  We can 
compare the locker or the open at a later time.  Torsens accomodating 
differing speeds of rotation, is a presentation you didn't make clearly, 
however it really doesn't matter, cuz it's irrelevent to the topic of chassis 
dynamics while turning.

Scott Justusson