There was a crudy conical rear hub in the batch of stuff my brother bought, like the ones 175s,250, and 400, use. All the spokes were hanging off the short side and like I said it was crudy as all get out. A trip through the solvent tank with a wire brush cleaned a lot off, and I discovered that something was stuck in one of the sprocket bolt holes. The bolt holes were a bit wollowed out, and I believe they should be 7mm or so in diameter for 6mm bolts. This one hole was blocked solid with a steel object and closer inspection looked like a broken tap. All the other holes had light thread makings in them also. There was no driving it out with a punch, so the only way to get it outwas to relieve it by cutting a wedge shaped section out, running from the edge of the hole towards the outer edge of the hub. Once this was done, a light tap with a hammer and everything fell out. The object was a hardened bolt, that I couldn't even touch with a carbide drill bit. It looked to me then, that what happened was the previous owner rode the bike with loose sproket bolts, then was going to try running 8mm bolts through the hole with an impact, and the result was a REALLY tight broken off 8mm bolt that cut threads deep into the sides of the hole. I cleaned the hub up the rest of the way in the sand blaster, and welded up the hole and the circumfrential fins and will finish them by hand and paint. Once finished, this should save the hub for future use.
My question is, is it acceptable, general practice to drill out the sprocket holes for 8mm bolts? There are 7mm bolts and nuts available and just to save a good hub for a rider project, that should be acceptable. 8mm bolts starts to make the edges kinda thin, but if this is commonly done so that common bolts can be used, I can deal with that.
Anybody else got any experience with this?
Thanks a lot,
Dan McEntee