Identify Crankpin

[ajsph]

I got this crankpin along with other AMC parts, can anyone identify it,it looks like an onepiece type, the dimensions are: Axle 3/4" Crankpin 1,20375" Outerdia. Ring 2"

Regards Poul Hansen

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[clive]

Poul
Single big end. If it is one piece it's probably an Alpha one as they made them like that for a while in the 80's (?) before reverting to a two piece type as the original ones from AMC were. The diameter of the part that goes into the Flywheels changed at one point but I cannot help with the date. Someone will know.

[ajsph]

I do not know if it is an Alpha, it came in this box
Poul

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[bjork]

As Clive says, if it is a one piece it was either made by Alpha or this firm in Syston near Leicester. I'm from Leicester and have never heard of that company, long gone I suspect. Maybe they copied the Alpha design?
If it is a one piece it's probably best not to use it as they were prone to breaking at the point where the diameter changes. That is why Alpha went back to the original AMC spec.

[clive]

Yes I broke a one piece one but it was on a 500 single pulling a double adult Sidecar!

[ajsph]

Thank you for your reply. All the AMC single I have seen are with 7/8" axle for the flywheels, this one is with 3/8" axle, could it be for a WD model.
Poul

[clive]

I made reference to the change in diameter earlier. I have a new old stock wd issue big end which has the reduced diameter. It's possible they were fitted to earlier pre-war models as well. Is 3/8 a typo as I think it more likely that the reduced diameter on the one I have is 3/4 but my garage is 1.5 miles away so I cannot check, but 3/8 seems very small.

[ajsph]

Thanks Clive yes it is 3/4"
Poul