Back on Track
 

Ackermann is one of those "black art" areas of race car design and tuning right now. I think that it is safe to say that while everyone understand how to adjust it, very few have a good idea exactly what the affects are. Earlier in the year Racetech had a series of articles (complete with pictures, formulae, geometry and data derived from observation of Williams BMW F1 car). Suffice to say a full discussion of the subject wouldn't fit in the space available here. A couple of take-aways that I got from the it all:

1) Ackermann can be used to fine tune the front end of the car. There is no "right" value, but there are better compromises for different cars/situations/tracks.

2) Ackermann doesn't mean a whole lot on fast corners because the wheels aren't turned enough to make it meaningful. So it really is a sharp/slow corner tuning aid.

3) Cars which inately push in slow corners can often be helped by adding more Ackermann. Conversely, cars which tend to be loose in tight corners can often benefit from less Ackermann.

4) Cars which are very loose in tight corners (think dirt track sprint cars) can often benefit from negative Ackermann. Yes, this is when the inside wheel turns less then the outside wheel.

5) The best way to figure out the correct Ackermann setting is to adjust it in testing and see what feels best. This is easier said then done since many suspension designs are not set-up for ease of Ackermann adjustment.

There is a lot more to the subject which you can read about in the back issues of Racetech .