The 
  angle between the steering axis of rotation and the vertical is called caster 
  angle. An inclination to the rear is marked above by positive sign.
  The wheels are pulled by the wake, whereby their flutter inclination is reduced. 
  With driving along curves additional resetting forces become free, which support 
  the straight-ahead position of the front wheels together with the effect of 
  the spreading angle. 
  If the Caster angle at the left-hand and right hand front wheel are strong different, 
  then the vehicle drives it to no more with released steering wheel straightforward, 
  pulls on one side. 
  The wake is indirectly measured, to which the dive angle modification is entered 
  with a reciprocal steering angle of 10 or°20 and projected with a formula.
  Caster angle, indirectly measured over the 20°- steering routine
at 
  MG F  1996 Caster should be: 4°06' ... 5°54'