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Classic Axle Failure

Discussion in 'Early CJ5 and CJ6 Tech' started by duffer, Apr 28, 2017.

  1. Apr 28, 2017
    duffer

    duffer Rodent Power

    Bozeman, MT
    Joined:
    Sep 17, 2009
    Messages:
    4,460
    I think we have all read about or studied stress risers with respect to failure. As I was gathering up scrap for a trip to the steel yard a few weeks back, I cleaned up the remnant of of the Spicer short side axle that was still stuck in the side gear of the D25. Absolutely classic failure with the fracture lines starting at the bottom of nearly every spline.
    [​IMG]

    Only a slight amount of rotational fracturing evident right in the center which probably occurred after it initiated shearing at the splines. Unfortunately, the remaining portion of the short shaft tore up the inner seal pocket so the rest of the housing went to the scrap yard too. I had initially entertained the thought of putting it back together as a temporary fix. That tore up surface was probably good as it resulted in the building of a D44 replacement.
     
    Posimoto and Hellion like this.
  2. Apr 28, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Aug 10, 2003
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    23,596
    Amazing. The cracks descend into the shaft until the diameter of the shaft is too small to withstand the torque. I wonder how much twist was needed to make those cracks. To me, this clearly shows why more splines is better. Since the stress focused at the bottom corner of each spline, the more locations that stress is distributed over, the more force the splines will withstand before breaking. The size (cross sectional area) of each spline does not matter so much as the number of splines.
     
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  3. Apr 28, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Sep 21, 2002
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    12,367
    Hmmm, did a healthy sbc have anything at all to do with that problem? ;)
     
    Twin2 likes this.
  4. Apr 29, 2017
    Mcruff

    Mcruff Earlycj5 Machinist

    Albertville, AL
    Joined:
    Sep 22, 2002
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    5,349
    Partially true Tim, the more splines is not always better but most times yes. The shape of the spline has more to do with its failure than anything, sharp corners are a no no on anything stressed, its why involute splines are more common now, no sharp corners and they can take about 3x the load, if the above splines would have had a .030 -.040 radius in the corners they would not have fractured near as easy, the sharp corner is where all the stress started regardless of what the shaft looks like.
     
  5. Apr 29, 2017
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Nov 22, 2003
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    8,102
    Mike you really should write some books on this stuff :)

    Seriously.

    H.
     
    Glenn likes this.
  6. Apr 29, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I totally agree Howard, Mike knows his stuff. :)
     
  7. May 9, 2017
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
    Joined:
    Aug 13, 2015
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    6,656
    Another example, on a bigger scale. I just found the busted piece of 1 1/2" 23 spline Dana 70 shaft from my old dump truck.

    [​IMG]
     
  8. May 9, 2017
    montanacj

    montanacj Member

    Joined:
    Jul 11, 2012
    Messages:
    794
    It's kinda pretty in its own way.
     
  9. May 12, 2017
    Hellion

    Hellion Regurgitated

    Eastern TN
    Joined:
    Dec 25, 2016
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    It's like a metallic chrysanthemum ...forged by Vulcan. :) Or something.

    Thanks for sharing, OP. Always nice to see metal carnage.
     
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