How to ID an EN40B crank

Hi,
Anyone know how to ID a 1275 EN40B Cooper S crank if the casting numbers have been ground off in the wedging/polishing procedure? I missed out on a crank because I was not able to confirm that it was an EN40B crank - anyone can stamp it EN40B/AEG480. All I had were pictures, so wasn't able to see in person.
Any physical traits to separate it from a later reground America or a AEG623EN16 crank?
Even if it were an EN40B crank, is there a way to confirm it without the services of a metallurgist?

Thanks,
Joe

[bcjoe]

Anyone????
I may have another chance at one, but it's also missing the casting numbers. Hand stamped EN40B/AEG480. Does anybody have any advice on this?
Joe

[mascher]

The lettering (stamping) should be raised not indented. This makes it very hard to fake. It's usually a little rough as well.

As far as identifying EN40B without the marking, it can be very hard if the crank has been wedged and ground. After grinding, especially if more than 0.010", the crank should be heat treated again. After heat treating the crank should be very hard. A file should skip over the surface instead of biting. Obviously, don't try this on the journals, however the webs should also be hardened. Some sellers won't let you try this, so unless the crank is well marked it's probably best to pass on it.

Cheers,

Kelley

[bcjoe]

Hi Kelley,
Is there a maximum number of times that a crank can be heat treated? Does it become more brittle each time? Is it possible to crossdrill a non-crossdrilled EN40B crank (I've heard that all the machining has to be done prior to heat treating - except grinding of journals)?
You're probably right in that it seems to be risky to purchase a crank without casting numbers. My gut feeling also.
Thanks Joe

[mascher]

As far as I know there is no limit on the number of times a piece of steel can be heat treated. It is, for all practical purposes, normalised (softened) at the beginning of the heat treat process and then hardened. Cranks are only case hardened, which means it's a surface hardening procedure. Only about 0.010" to 0.030" is hardened. To be safe the crank should be heat treated each time it's turned or built up.

There are conflicting opinions about whether crossdrilling is even necessary and both sides are represented by people whose opinion I respect. If your not going to run high rpm it's probably not necessary.

Cheers,

Kelley (from beautiful Charlotte NC where there's a heattreater on every corner)

[bcjoe]

Thanks for all the good advice Kelley.
I'll keep looking for a good one.
Joe

[bcjoe]

Why is it that all the cranks being offered to me have had their casting numbers ground off and have only re-stamped ID. Also most of those cranks are only 10/10 or 20/20, yet I'm seeing cranks with all original stampings (EN40B/AEG480) at 30/30 or 40/_ on eBay.
Somebody who is offering me a crank just told me that some of the cranks left the factory without the EN40B/AEG480 stampings on them. I don't think so, but I've been wrong before. Is this true?
Thanks Joe

[mascher]

If it's true that there were significant numbers of EN40B cranks manufactured without casting numbers then there is no way to tell the difference between a standard Mini crank and an 'S' unless you have an metallurgical test done. So, in my opinion, unless the test has been done you should never pay EN40B prices for an unmarked crankshaft.

Usually one wants an EN40B crank for originality's sake. For originality's sake it must be marked because there must be proof of its originality.

Cheers,

Kelley