<VV> Ackerman

[Padgett]

>NO! Changing the box only will NOT change the Ackerman angle. Only
>changing the arms will do that.

Have to think of the drag link, idler arm, pitman arm, and steering arms as 
a moving parallelogram that controls the steering geometry. The steering 
box is just a gearset that changes the steering rate but not the geometry 
(so long as the pitman arm pivot is located in the same place.

The Ackerman Angle takes into account the fact that the inside wheel  on a 
turn is following a shorter radius and needs to turn more than the outside 
tire. If the radius of one is wrong, you get scrub (one front tire fighting 
the other). In a street car this is not good

In Real Racing the ackerman is not that important since the inside tire in 
a turn will have very little weight on it and tire wear is usually not 
important. Besides the steering angles at high speeds are small.

In a low speed autocross where much wheel flailing may occur at low speeds, 
the ackerman needs to be correct because scrub will increase understeer and 
both front tires are having an effect, something you really do not need. 
Repeat after me: "Upsetting the front end geometry causes understeer".

Years ago I did not bother with quick steering in my Corsa, at high speeds 
you really do not need to move the wheel much (a whole 'nother driving 
technique I use is called "slow hands"). I did use a shallower dish and 
smaller diameter steering wheel which accomplished much the same thing 
without upsetting the geometry.

For me in an autocross what I want is very positive steering, not 
necessarily fast and the Corvair is quite suited to steering with the back 
end. When driving at 10/10s (no-one can drive at 9/10s) you really get a 
lot of response from small inputs.

BTW: what looks fast with arms and elbows flying and large slip angles, 
usually isn't.

Padgett