Vehicle Dynamics 1

[martin a]

While reading through some recent posts I noticed that there was a general consensus that advanced driving advice rarely touched upon vehicle dynamics. Maybe someone has gone over this before, but if not hopefully I can shed some light on this subject and debunk a few myths. All this stuff and more by the way is what I teach learner drivers on their first day to make the rest of their driving lives safe, easy and fun.

First of all oversteer and understeer which are badly described in 'Roadcraft' and mainly it refers only to when too much power is applied to the driving wheels, causing them to lose grip. Hence the old adage: rear wheel drive cars oversteer, front wheel drive cars understeer. True, in those circumstances but not necessarily all others. So, on to a better explanation. I hope.

Common sense may tell us that when we look at a normal car we think of the front wheels steering and the rear following their path, but this is not the case, it only seems that way. The car is supported by two steering front wheels that make it want to change direction and two fixed rear wheels which make it want to go straight on. Its actual path is a compromise between these two but almost never a 50/50 split for reasons which I'll try to explain in the following post.