The binder bolt for my '82 Miyata 1000's seatpost kept coming loose and it was never easy to tighten. Here's some pictures of the bolt and the seat tube. You need something like a flathead on the nut end and allen on the bolt. But the bolt pushes into the flathead as you try to hold the nut in place.
I replaced it with a new bolt but it's ugly and external. I really would like something closer to the original that fits neatly into the seat tube similar to the way it's cleanly designed. Not sure where/what to look for.
http://i24.photobucket.com/albums/c1.../seattube1.jpg
http://i24.photobucket.com/albums/c1.../seattube2.jpg
http://i24.photobucket.com/albums/c1...inderbolt2.jpg
http://i24.photobucket.com/albums/c1...inderbolt1.jpg
Didn't know if this was a question best for CV folks or the mech forum. Let me know, don't want to cross-post.
thanks,
-Michael