Ackerman is probably the most important geometry setting for a race car or trying to get a car handling well, for those who dont know it is measured in percentage, the closer you can get your car to 100% ackerman angle the better, unfortunately most car come no where near that, so in racecars the extend arms out at the bottom for 3 reasons 1. neg camber 2. ackerman angle 3.caster how do we work out this angle, well from memory and chris could help on this, draw and imaginary line across you car from ball joint to ball joint, then using the centreline of the car you now have a big T, draw a line at 30 deg inward on each side i think and this will give you your ackerman point on the car where the two lines intersect, to get the percentage you count the front line as 0% and the centre of the diff/swing arm as 100%, so with a tape measure to measure the distance and apply that to a percentage graph.
Now there are other tools to help with this as well the easiest to use is a tremmel, panel beaters have been using them for years to fix chassis, because built in to your cars subframe is a bunch of reference points, how does this help us well fuk all really because of the way the lower control arms are mounted, which is why race cars run double wishbone suspension so these arms can be spaced out accordingly or have the amount built into them at the time of manufacture,to get things further out you need to start modifying arms and mounting points and making offset bushes, now we cant put it all into one post this is supposed to be a resource for all so if you put your FAQ here we will do our best to help you out