How loose is the nut holding the springer front end. I would elevate the front a few inches, and torque it to where it has only a small amount of fall away (when you crank the front end left or right, all the way-and release it it barely moves to the middle or less!) If you look at my posts, you will come across one called "Brain Damage", it is a trike I built with a 40 inch over stock springer. Before I torqued the nut down it would shake and wobble. Just an idea.