I'd like to replace this stem expander bolt, because the head is so chewed up that I'm not sure I can get a wrench to fit it securely. It's from a TTT stem, and the bolt head recesses so deeply into the stem that little of the head is exposed once it's tightened. A few more washers under the head would have helped, but the damage was done long before I got it.
One thing that puzzles me a little is the necked-down section of the bolt just below the head. I don't recall having see that before, and can't think of what its purpose is. Is there some reason I can't replace this with just a straight bolt of some kind? Haven't tried to figure out the threading yet, but it's finer than the threading on most of my other stems.