During the annual, we discovered a crack in the tailwheel head. The grease seeping out of the crack gave it away. Has anyone ever seen a crack like this? Can't remember ever landing hard enough to crack the tailwheel. I think the rest of the assembly is fine and will be ordering a new head from Alaskan Bushwheels in the morning. Just seeing if anyone has ever seen anything like this? Tailwheel is on a 1947 Stinson 108-3.

There has been a post or two on the 170 forum about very similar cracks.
The other place they fail is the king pin.

I would suspect it started from the hammer marks on the rear.
Possibly center bolt was a little loose at one time too???

New parts should be here Tuesday. I might know more when we take it apart to rebuild it. I've only had the plane for a year so do not know the history of abuse if any.

The back end of that thing looks like it’s suffered some extreme abuse. These are castings, ya know.....

MTV

I had one do that on my C-170. While I'll never know for sure what caused it I have a good idea. I had a really bad tailwheel shimmy after landing and upon inspection I found the bolt holding the tailwheel assembly to the spring had become slightly loose. It was tightened and a few days later I found the crack, much like yours except it was much more visible from the bottom and only looked like a pencil mark on the top. I suspect the loose bolt / shimmy did it. Yours looks like it took quite a whack from something on the aft edge.