Re: Torsens par avion

[AUDIDUDI@delphi.com]

> I'm not sure your 25% assumption to be true....  What I have found is
> that the torsen tends to send more power to the front drive wheels than
> the rear when in low cf conditions....  That creates inherent understeer,
> and have not driven a torsen audi yet that has addressed that
> phenomenon....  Can it be done with suspension mods, I suppose, but a
> challenge to the best of designers (go for it jeff).

Well, I'm hardly a "designer" -- "barely talented amateur" seems much more
accurate! -- and the only reason I'm interested in making a Torsen work is
because I think it has the potential to provide more traction while you're
accelerating away from a tight-radius corner under full power.  Given that
my emphasis is on autocross performance and not track stuff -- I don't see
more than 60mph on most courses and most of the time I'm under 35mph -- my
requirements are unique to my situation.  If I was going to be doing track
duty where the corner radii are larger and the minimum speed is 60-70 mph,
I'm pretty sure I'd go with a locked center diff instead...

> My thinking is that a torsen "hunts" within it's design perameters, and
> that creates a huge engineering nightmare

This is definitely my experience.  With a Torsen, the car's behavior at the
limit (and I do mean THE limit ... beyond what I would ever drive at on the
street) is unpredictable.  When you have the tires loaded to the limit, the
Torsen tends to disrupt the balance of the car by transferring power around
more quickly than you can compensate for with the steering and throttle ...
this causes the tires at one end of the car to overload, break traction and
then start to recover as the power's transferred to the other end where, in
turn, the tires are overloaded, break traction, etc.  The cycle will repeat
itself ad infinitum (or until you slow down so the tires have some traction
left to cope with the additional power that can be dumped on them instantly
from the other end of the car).  NOTE: This ONLY happens when you are truly
at the limit of the tire's adhesion ... for street driving, you will notice
none of this and the Torsen works very well indeed.  

     _             _             
    / l       l o l  \       l o   Jeffrey Goggin
   /__l l l / l l l  l l l / l l   AudiDudi@delphi.com
  /   l l_l \_l l l__/ l_l \_l l   http://people.delphi.com/AudiDudi