I made a trailer, it mostly works, I like it. Today I put a pretty heavy load on it (bookcase, maybe 90 pounds) and the dropout brackets came loose (before I started riding). They look like this:


(bigger image)

The connections between the metal and the 2x4s is what's wiggly. It's held together by screws.

I'm thinking maybe If I took it apart and replaced the screws with bolts it would do better. Maybe I need to put bushings in the 2x4s to put the bolts through? (I know bushings are usually used with rotating parts, but they would also help keep the bolt stable in the 2x4.) Suggestions?