[Gladman]

Quick thought update...

I decided to go pull out the centering spring on the rack to see if it was flattened out or something and made an interesting discovery.

With the spring completely removed I can move the steering wheel back and forth the exact same distance that it vibrates under speed without the rack moving. The shaking looks to be directly related to the distance of play in the rack when this spring is removed, which might suggest the tension is too loose and it allowing a miniscule amount of poor balance to effect steering.