So, I've done some more reading and I have a few considerations to post. The front geometry is bad for several reasons including:
1) The steering rack is too wide for the car, requiring short tie rods instead of longer ones. When the suspension goes up or down, the short length of the tie rod compared to the longer control arms causes the end of the tie rod to pull toward the chassis more quickly than the ends of the control arms. This in turn causes the steering arm on the upright to be pulled towards the chassis faster than the upright, which causes the upright to rotate about the kingpin axis. As this happens, the wheel's toe substantially changes.
The usual way to avoid this problem is to use tie rods that are about the same length as the control arms and to locate the steering rack so that the tie rod is parallel to a control arm.
2. The kingpin axis doesn't even come close to intersecting the tire contact patch. More precisely, the axis of the kingpin does not pass through the plane of the wheel at ground level. This means that there is essentially a lever arm giving the tire leverage over the steering. So when you hit a bump, the wheel is pushed backwards, this in turn creates torque around the kingpin which manifests in a sudden, violent jerk in the steering wheel. Basically the offset of the kingpin is dead wrong. This sort of error is quite literally a text book mistake,
"It is disastrous, as some of the pioneer designers discovered, simply to move the steering axis (the kingpin) smartly sideways [inwards]. That makes room for the hub and permits the swivels to be moved further apart, thus reducing the stresses on both. Sadly it also means that every road shock tries to twist the wheel about its steering axis - not exactly the kind of feel we were looking for. Far from each wheel being naturally self0centering, each will be trying to twist itself around its steering axis in a state of constant conflict with the other. Such permanent tensions are bad news in any kind of engineering, but especially in a system as safety-related as the steering."
-Car Suspension at Work: Theory & Practice of Steering, Handling, and Road Holding. Jeffery Daniels 1988. Page 77-78. (
http://www.amazon.com/Car-Suspension-Wor...pension+at+work )
I'll post more on this later. I've been very busy working 10-12 hour days at a new job, so my free time to post is sparse. I hope this helps explain whats going on with our beloved trikes. They are wonderfully fun, and I would enjoy mine even more if it didn't occasionally try to rip the wheel out of my hands and kill me when I hit bumps on the freeway (75mph+).
Good night everyone.
P.S. The exhaust heat shield mount tore out of the muffler last night, leading to quite a lot of noise and some improvisational welding. Enjoy ->
http://www.youtube.com/watch?v=m5PbUq8lvww
