Crank Bolt

[8portChris]

Anyone know what thread the bolt is that holds the bottom pulley to the crank ? i know its something a bit weird but what ?
I really need to find out, so i can see if i can get a 'tap' for it.

Thanks

Chris

[Cooperman]

I think it's 7/8" UNF, but I'm not absolutely sure. It'll be a blooming big tap.
Have you stripped the thread? Just wondering why you need to tap it, that's all.

[8portChris]

Its 5/8 UNS 16 tpi.
No its not stripped, just goes a bit tight too soon (before the bolt is holding the pulley)

Chris

[Cooperman]

That's very unusual. Perhaps you should investigate the reason for this before trying to effect a remedy. It the hole full of dirt, or is the thread damaged in some way which a tap might not eradicate?
Try flushing out the hole with 'Jizer' or similar, then blowing out with an air line, then running the bolt in and out a few times after lubricating with WD40 or ordinary engine oli.