understeer/oversteer

[fjbauer@dsavm.e-mail.com]

Frank J. Bauer                                                                  
dassault systemes of America     email:fjbauer@dsavm.e-mail.com                 
Subject: understeer/oversteer                                                   
huw sez:                                                                        
> OK, I'm sick of trying to remember what someone told me once.  What is the    
> definition of oversteer and understeer please?                                

understeer means the front tires are slipping more than the rears.              
oversteer means the rear tires are slipping more than the fronts.               
neutral would be if your steering input was just enough to follow the           
arc of the turning radius.                                                      
understeer is considered a "safer" condition for most drivers since it is       
a stable condition - you initiate your turn by steering toward the center       
of the arc, the fronts start to slide, you dial in some more steering           
toward the center of the arc, etc.                                              
oversteer is an unstable condition - you initiate your turn by steering toward  
the center of the arc, the rears start to slide, you counteract by steering     
away from the center of the arc until the steady state is reached, but not      
too far or you will initiate a new turn in the opposite direction and not too   
late or you have already spun.                                                  
the advantage to oversteer is that you are better set up to apply power         
upon exiting the turn.  plus it feels great  =8)                                

in general, RWD's tend to (or can be induced to) oversteer while FWD's are      
primarily understeer.                                                           
this is an oversimplification since this feature can be affected by weight      
distribution, engine power (and it's distribution in AWD/4WD), weight transfer, 
suspension setup, coefficients of friction at the contact patches, steering     
input, etc.                                                                     

hth...                                                                          
frank