Need opinon on cast iron shaft

http://home.thezone.net/~bpriddle/shaft.jpg
http://home.thezone.net/~bpriddle/shaft_closeup.jpg
This is a cast iron drive shaft on my new snowmobile. It is 1 inch thick. It
cracked for no reason that I can see. But it has a weird centre core, that is actually off-centre. Can anyone explain or be able to determine by looking at it if this could have been a faulty shaft? The area circled in the close-up pic also sticks out alittle.
Thanks for any help
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It
Pictures need to be a lot higher resolution and in focus. If I could see the fracture it might be possible to comment on it.
Is it cast iron:- probably not Is it defective:- probably not
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When I pick up the sled either today or Monday, I'll ask to see the shaft and get better pics of it.
Thanks

thick.
that
in
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I really doubt it's cast iron.
what kind of sled?
how hard were you pounding her?

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Yea, I think I was wrong..its not cast iron.
I was only doing 10mph at the time, was hardly moving. I was riding it sort of hard the day before but it seemed fine. I have an 04 Arctic Cat Mountain Cat 570, so torque should not be an issue.
Cheers

core,
by
circled
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I checked out your website - you probably fractured it days / weeks before while giving it a pounding. Then it finally failed for you.
A 570 will give you plenty of torque, especially making all those jumps!

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LOL..nice try...thats my old 96 Bearcat 340 on my web site. It was 8 years old when I sold it this year for the Mountain Cat. Never had shaft problems on that sled and I rode it HARD for a 340. I have no pics of MC action yet as there hasn't been many.
If a sled can't handle the odd jump and some hard riding, then whats the point of having it ?! lol
Cheers
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Yes it is probably not cast iron. Maybe a kind of Al-Mg stuff. This kind of failure look like you've gotten too much load for the design. I think if you replace the part with another similar one you will have the same failure with the same conditions.
I really don't agree with the choice of the designer about the hexagonal shape. It is better to take a round shaft. It is better also to use cast iron.
bye

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Al-Mg doesn't have red-oxide rust on it, would be white.
it's probably hex cold rolled steel shaft which eliminates welding and making the sled cheaper to produce.
it looks like a typical fatigue crack. probably an inclusion or minor surface defect acting as a stress raiser. if I'm not mistaken the break is at the drive side of the shaft. 1" hex might be undersized for the torque. round would be a better shape. interesting how it broke right at the collar. poor design?
consider buying yamaha next time?

before
jumps!
years
problems
yet
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Brad,
Although the resolution of the picture is not the best, and fracture surface features are hard to discern, the shaft appears to have failed through fatigue. Cracking likely started at the sharp corner or juncture of the hexagonal portion of the shaft and collar. The "off-center" core region you refer to (encircled in the photo) appears to be the final overload region where the shaft finally separated. An off-center final fracture region in a shaft indicates that the fatigue failure was strongly influenced by rotational bending loading experienced by the shaft as the snow mobile was operated.
Personally, I don't feel the shaft was manufactured from cast iron. Likely steel; which may not have been heat treated to improve its strength.
Regards,
Greg

It
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I hate to disagree with the masses, but I had no trouble seeing the shrink hole in your image which is typical where the thickness changes. I would keep the old part if they are not willing to accept that is a casting defect. Alan Black San Martin Casting & Foundry www.sanmartin.com

It
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