Mark,
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. The British size would be BSC Coarse threads but I think that was probably a theoretical standard, at least in this size. Whitworth bracketed it at 18 and 22 TPI so it seams silly to designate 20TPI. I know I found an easy answer to this when I faced the same quandry so I must have worked out the metric solution before.
Joe Bender-Zanoni Great Notch, NJ
Mark Bulgier wrote:
>I just got a Williams AB-77 (splined-cotterless) crankset (chainset in
>UK?) from a very reputable dealer and all-around nice guy. It came
>without the bolts that mount the cranks on the axle. Said dealer will
>take it back for refund, but I'd rather keep it.
>
>They are not the same as Campy and all the others. Look to me to be
>5/16" 20 TPI. The common thread pitches for 5/16 in the US are 18 or 24
>threads per inch, and I haven't found a source for 20 TPI yet in generic
>hardware-store-type bolts.
>
>I'm thinking, somebody here has to have those bolts, eh? Did your
>aluminium cranks wear out leaving the steel bits in fine shape? Did
>your bearing cups and cones pit and become too grindy to ride? Surely
>you would save the rest -- if you're a packrat like me anyway!?
>
>The price I will pay will not be the "one pair of bolts" kind of price,
>it will be more the "you saved my crankset!" kind of price.
>
>Oh well, it's worth a try.
>
>Failing to find real Williams bolts, maybe someone here knows where to
>get generic replacements.
>
>In case anyone wants to know what an AB-77 is, here is a period ad:
>http://bulgier.net/pics/bike/Parts/Cranks_Pedals/Williams_AB-77_crankset
>_ad.jpg
>or http://tinyurl.com/
>
>and a good pic of the splined axle:
>http://bulgier.net/pics/bike/Parts/Cranks_Pedals/Williams_AB-77_crank_ax
>le.jpg
>or http://tinyurl.com/
>
>
>Thanks in advance,
>Mark Bulgier
>Seattle WA USA