Does that other number mean anything?
Cooper S crankshaft ID
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Vegard
- 1275 Cooper S
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Spider
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Re: Cooper S crankshaft ID
As best as I can determine, it is EN40B. Not all cranks were stamped with that.
One notable identifier of the EN40B Nitrided Cranks is they don't readily rust as easily as a non-Nitrided Crank.
The other simple test is to put a file to it somewhere where it has been machined (on the web, where there is a notch machined out would be OK) to feel how hard it is. A file will almost slide over it. Don't bother trying this on an unmachined part of the crank, the skin left from forging is hit and miss as far as nitriding goes and will be less likely to be nitrided at all on those parts.
One notable identifier of the EN40B Nitrided Cranks is they don't readily rust as easily as a non-Nitrided Crank.
The other simple test is to put a file to it somewhere where it has been machined (on the web, where there is a notch machined out would be OK) to feel how hard it is. A file will almost slide over it. Don't bother trying this on an unmachined part of the crank, the skin left from forging is hit and miss as far as nitriding goes and will be less likely to be nitrided at all on those parts.
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smithyrc30
- 1275 Cooper S
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Re: Cooper S crankshaft ID
Did you go out with a metal detector to find that? It looks to have been dug up from a field. 
The non cross drilled S crank had a forging number of AEG316. The EN40B is normally on the other web, where yours appears to be ground off.
The non cross drilled S crank had a forging number of AEG316. The EN40B is normally on the other web, where yours appears to be ground off.
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Vegard
- 1275 Cooper S
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