Crank Shaft ABC Motorcycle information

Peter

I have two cranks . 0.445 inch and 0.438 inch both with 3 in a circle, taking account of the rust.

T

Hallo Peter, Hallo All,
Is this just a ruse to see how many crankshafts we are hoarding?
Anyway, I have a shaft ("ex Geoff Moore") stamped variously with 3, 5, 6 (or is it 9?), and 7, all in circles. Plus 11 not in a circle, and several indentations, perhaps from hardness tests.
It's difficult to get a micrometer onto the centre web, but this one is 0.409", or 10.4 mm.
Sopwith crankshafts don't have a reputation for breaking, so I would think that a compromise of 10.5 mm./0.414" would be very safe.
Great stuff, Peter, let the lathes roll!

Hi Paul and Tony
Thank you for your response. Paul , you are correct, I want to add more scrap crankshafts to my collection.
I wanted to keep this discussion Sopwith but it seems as if it was not only Sopwith who were thinning the center web. Gnome Rhone also seem to have thinner center webs on some of their crankshafts. See the photo. The range seems to be 11.3mm to 10mm

Detlev and I spent two hours on this today and we will be making the center web 10.25 mm thick.
Regards All

The first photo is the final crankshaft without the thread the key ways and the final size on the journals.
The second photo is after heat treatment. The area where the thread and key way must be is painted out before heat treatment and can be seen on the second photo.. now we will see how much distortion we got during heat treatment. I will report back soon. Regards