rat,
Did you change the rear wheel or something? Was the arm that you're having trouble with ever fitted on that wheel?
I've seen brake arms in both coarse and fine spline. If I had to guess, Honda probably only used at a maximum two different spline pitches/sizes on their early 70s bikes.
For what it's worth, early 70's Honda brake arms were stamped steel deals like this,
Honda go sideways!
Edited by - krapfever on Apr 18 2007 12:04:46 AM