Bushwheel Fork and Tail Shimmy

[Steve Pierce]

Here is a picture of a spring pad I made from a big truck mud flap and installed between the tail spring pad and the spring to help the angle. The next picture shows the good angle that solved the shimmy on this FX3 Carbon Cub.
Spring pad resize.jpg

Good angle resize.jpg

[sierrasplitter]

Thanks Guys AB Supercub spring Ordered ! And thank You Steve for the pics. Clears up everything.

[sierrasplitter]

SuperCub spring was installed 5/18 Still have the Shimmy ( Dammit)

IMG_9779.JPG Also, pic is the correct orientation before I post ?

Getting tired of this. Real Close to going back to the standard Scott Fork and small tail wheel

[JPerkins]

How many springs inside the tailwheel head? Usually they have three but provisions for up to five. These are the springs that press on the thrust plate and would help dampen the shimmying. An extra one or two might help. I've got a couple spares (I think, have to check) if you want to try that.

Sent from my SM-G930V using ShortWingPipers.Org mobile app

[sierrasplitter]

Hey Jason . I dont know, but Im about to find out. I had a shop rebuild the head at the same time the larger fork and 404 tire were installed. So, I believe I have the head angle good with the supercub spring. I also know my new 404 tire is out of round ( That could be the issue) . Dont know if it was round and I banged it up or if it was out of round from the get go.
But, Its time I tore the head down myself to get a better understanding of how it works and to check to see if it was put together correctly.
But I may just have to go back to the Stock 3200 fork and small tire. Just dont seem to be getting anywhere with this AB fork. Too much asphalt under my tires

[andya]

I could see if the tire was out of balance or out of round it could induce the shimmey

[sierrasplitter]

It sucks. The tire only has maybe 20 landings on it? I guess a couple were a bit too hard. But, eliminating all the other variables one step at a time

[Gilbert Pierce]

With your plane on the ground, can you push the rudder left and right and disconnect the tailwheel from the rudder?
If so, does it take the same force to break it loose left and right?
How much force does it take to break the rudder free from the tailwheel: not much, a whole lot, or a moderate amount?

[sierrasplitter]

With your plane on the ground, can you push the rudder left and right and disconnect the tailwheel from the rudder

You mean push the rudder until the tail wheel breaks loose? Have not tried that .
It does seem to break about the same as the smaller wheel I had before.
The first time I picked it up from the shop it was way too tight. You could turn one direction while taxiing but the bearings were so tight full rudder input in the opposite direction would not change the direction it was traveling in.
So I took it back and had them loosen it one notch . I tried it and had shimmy. Went back to my hanger and put the tail o the stand and could feel the bearings were still a bit bound. You know what a too tight bearing feels like......kinda " notchy" . So I adjusted until there is no slop in the head but it feels smooth.
Tested with pushing on the tail to get it to break and seems ok
The Shop that did the work doesn't have a lot of tail wheel experience but they have done a few

My rigging seems good. It sits just like the one in Steve's pic above. Same springs , same tension at rest

I will try breaking it loose pushing on the rudder

[Gilbert Pierce]

You need to find a mechanic experienced with working on Scott Tailwheels. You don’t tighten or loosen the swivel bearing to adjust the unlock force.
I would be concerned that the internal parts were even assembled correctly.