I was reading how to incorporate an ankerman angle on my spindles, right now it is a little off. The spindles we have are from blue sky and have 15 degrees of a kingpin angle and zero camber. Since the kingpin is tilted and the ankerman is measured off of it where do I measure from the kingpin?
Just like the diagrams on page 19 shows the various angles all have to do with your specific cars wheelbase and track, the size of wheel you are using, the length of the spendles from the kingpin to the center of the wheel, etc. So you need to measure the components of your car and then use Trig--my kids use TAN usually--to find the various angles. If you car is short with a wide track the ackermann angle is greater than if it was narrow and long, etc.
So measure the distance between the kingpins at the height from the ground that you tie rod will be since the kingpin is angled, and divide it by two. Now measure the straight distance from the center of you front axle to the center of the rear angle like on the bottom of page 19. Take the Tangent of that angle and you will know your angle. Ours are usually around 18 to 20 degrees.
The kingpin angle should be found like the upper right diagram. Ours are usually about 16 to 18 degrees.
For Caster I like mine tipped back about 15 to 25 degrees so both front tires dig in on a corner. I set my Camber at about 2 to 8 degrees so the wheels tip in at the top about 1/2 to 1 1/2 inches from the bottom.
For us these seem to work but again it depends on your specific car and components.
Nitoragro - Ackerman angle can also be built into the steering arm (Pittman arm) on your steering shaft if you are using a steering wheel rather than twin levers. This is difficult to explain without drawings and pictures; if you see me at our next race I can show you on my car.
As a "rule of thumb", it's better to have too little Ackerman than too much. Too much Ackerman angle causes the car to "drag" the inside wheel around corners which is excess rolling friction. Running too little Ackerman causes some side scuff on the front tires, but doesn't seem to be as severe. If the Ackerman angle is perfect there is no additional rolling friction. Few cars are 100% perfect; we just try to get it close.
Different builders have different preferences on front end geometry. The final design is usually somewhere between what you think is ideal and what is practical. I build my spindles with 0 kingpin angle. Then I build my front axle with 7 degrees positive caster and 7 degrees of negative camber. There are lots of ideas, theories, and arguments, but this works for me. I set my toe at 1/16 inch in. Again, there are different opinions here. Some prefer to run toe out. Experiment and do what works for you.
