RE: [CR] Help! Need axle bolts for Williams AB-77(splined-cotterless) crank

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Subject: RE: [CR] Help! Need axle bolts for Williams AB-77(splined-cotterless) crank
Date: Wed, 30 Nov 2005 23:46:06 -0800
Content-class: urn:content-classes:message
Thread-Topic: [CR] Help! Need axle bolts for Williams AB-77(splined-cotterless) crank
thread-index: AcX2Ijb40n2oPureRpCo1lR1wEHDpgAJnP1g
From: "Mark Bulgier" <Mark@bulgier.net>
To: "Joe Bender-Zanoni" <joebz@optonline.net>
cc: classicrendezvous@bikelist.org

Joe Bender-Zanoni pointed out
> I think the answer is 8mm X 1.25 which is a standard metric
> coarse thread! Even if 5/16X20 is right, the metric size is
> is so close it should work anyway.

Yay! Thanks Joe. I just checked with some bolts I had - 8 x 1.25 is a very common thread - on bicycles it is found on many Japanese handlebar stems, like SR and Nitto. First one I tried didn't thread in, then I noticed the first thread was banged up. Second one also no-go - also a bad thread (what's the chances of that? At my house, a sure thing apparently). Unthreaded the third bolt from inside a nut, so it was a known-good thread, and it fit perfectly! Well actually a bit BETTER than the original-equipment bolt, but I can live with that! ;)

8mm is a TINY bit bigger than 5/16" (two and a half thousandths of an inch bigger), enough to take out some of the wiggle that the Williams bolt had. And 1.25 mm thread pitch works out to 20.3 TPI - close enough to 20 TPI that the bolt doesn't begin to bind noticeably over the half-inch or so length of engagement, despite being slightly oversized.

Since everything I'm looking at and measuring is grimy, and made to fairly loose tolerances, there's a chance the Williams was actually made to fit 8 x 1.25, not 5/16" 20 TPI as I said earlier. Given how close they are, we may never know unless some Williams factory documents surface.

So now I just need to find them with an appropriate head on them, thin enough to fit under the dustcaps. I'm not against lathe-turning some down that are a bit thick-headed, having a bit o' that problem meself. Allen-headed Japanese stem bolts will not work at all unfortunately, so I'm still looking, but it's looking good.

Mark Bulgier
Seattle WA USA