Thomas,
I had a mean nosewheel shimmy that would get worse if the tire pressure was much outside of 14-16 psi but it was ALWAYS pretty bad.
The usual stuff to try:
Your nutcracker bolts need to be tight. on the top and bottom bolt, the bolt goes through a bushing that should have sharp teeth all the way around the ends where the bolt goes through. Those teeth should bite hard into the nutcracker metal. However, if the teeth are worn down or the nutcracker metal has worn away... you need new parts.
Get the weight off the nosewheel and make sure there's no slop in the wheel bearing. Then disconnect the steering rod and make sure it doesn't have any front-to-back slop (that it doesn't move without moving the yokes).
Aaaaaand those didn't fix it for me. What did fix it, instantly and 100% better with no more shimmy at all, was when I took apart the nose gear to rebuild it. The
outer oleo cylinder
of the nosegear had a
big brass bushing
on the bottom - the inner part oleo cylinder moves through this bushing on an o-ring.
There's also an upper brass bushing inside the outer cylinder that the inner cylinder also rides on. It wears down but there's no way to get it out! Fortunately you can just slide a new one up there and sink in a couple screws to hold it in place.
Anyway, I replaced all that stuff. No improvement! But one thing bothering me was that the bushing didn't fit very tight. It turns out that my outer shaft must have become slightly bell-mouthed. I got my hands on a good used outer cylinder and presto - the bushing fit into the cylinder was much tighter. Now the inner shaft is held more securely and doesn't shimmy anymore.
Vernon can hook you up with all the parts you need. My recommendation is that if all else fails, check whether that lower bushing and the lower end of the outer cylinder have become bellmouthed. All that shimmying kind of hammers on it and eventually it's gonna be shaped more like a blunderbuss barrel than a tube.
