Broken Crankshafts at Easy

For those who obsess about exactly how their 356 left the factory!
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Bill Oldham
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Broken Crankshafts at Easy

#1 Post by Bill Oldham »

This Saturday, if Jim opens up the shop for the Greasers meeting, there will be the unveiling of a rare two-piece crankshaft when I split the case on my (now very noisy) 1960 normal. Thought it would be fun to see whats inside (besides some metal grit generated by the divorce of the front and rear sections of the crank) and speculate on the cause of the failure. Old age or a bad regrind, or? Bring donuts and opinions to Emeryville.
Bill

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Jim Breazeale
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Re: Broken Crankshafts at Easy

#2 Post by Jim Breazeale »

Bill

I'll be open. I may have to clean up some floor space as rain is predicted. Donuts and coffee taste really good in bad weather.

Regards
Jim Breazeale
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Brian R Adams
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Re: Broken Crankshafts at Easy

#3 Post by Brian R Adams »

Jim,

You could offer a door prize for the best SF Giants hat. :P

Brian
Welcome to the era of policy-based evidence-making.

Difficile est saturam non scribere (Juvenal)

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Bill Oldham
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Re: Broken Crankshafts at Easy

#4 Post by Bill Oldham »

To complete the story I thought I would post a couple of pictures of my new two-piece crank.
I do not have the party photos of us hovering around the patient ... they are on someone else's camera, but I have a couple I took later at home of the crank. It broke at the #4 bearing journal so the rear part of the crank was supported only by the 4th bearing and the 3rd rear main.
Thus the #4 rod was working on a cantilevered part of the crank... must have been a lot of flexing going on in there. Interestingly, the 1 cc or so of metal that was missing was reduce to quite small pieces, really small pieces, so I would speculate that the hardening was a lot of the way through the missing chip to make it that brittle.

As for the cause of the break, beyond old age, it appears to me that the radius on this journal was kind of sharp ... see if you can tell from the close-up photo.
The case and the rest of the parts "look" fine, measurements will tell if the bearing supports got pounded.
Attachments
detail.jpg
short end.JPG

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