mechanical turn plates.

[smkjoe]

I bought a set of Intercomp mechanical turn plates, these are not digital. no instructions came with them, nose anyone no how to zero them and has anyone used them, an give me some infomation on them, also how do you adjust akerman.
Thanks, Gary.

[dynoman14]

You jack up the front end and put the plates under the tires with the pointer as close to 0 as possible. Set the car back down and once you shake the car up and down a little to settle the suspension back down, you record the settings on the plate as ZERO. Some of them have an adjustable pointer you can move to ZERO.

Now you turn the wheel to the left and about every 5* of wheel movement I take a reading on both plates. Once you get about a revolution of the steering in you will have probably gone more than you would ever go on the track.

This will provide you with a dynamic toe curve or Ackerman curve.

You can do the same thing turning to the right and see what happens but unless you are road racing it should not affect you.

Ackerman is changed by lengthening the steering arm on the spindle or shortening it to create a slower toe gain or faster toe gain. That is why some LF spindles have gator teeth on them so you can adjust the position of the tie rod making the spindle steering arm longer or shorter.

I can tell you but I will leave it to you to discover what changes make more or less Ackerman...it is more fun to learn on your own because that way it will imprint into your brain and you will learn this forever.

At Daytona we used to run reverse Ackerman, at a short track you run positive Ackerman which means the left wheel turns in faster than the right wheel. When Cup drivers refer to the LF digging into the track, they are referring to the combination of Ackerman and Caster to crank weight and heat into that tire.

The negatives are burning up the LF but I have not seen that happen much, most LF outlast the other 3 tires 10:1. When you get things going LF tire wear will increase.

That is a simple way of explaining it. Herb Adams suspension book goes into detail if you want more info.

[smkjoe]

Thanks, that explains it well.
Gary.