Crank Hub Galling

Discussion in 'PSI Superchargers Tech Questions' started by TOL, Dec 30, 2015.

  1. TOL

    TOL Active Member

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    Dumb question......

    What actually causes crank hub galling and metal transfer? Is it because the hub is trying to wobble up and down on the nose of the crank while rotating? Or because the hub is trying to rotate around the nose of the crank due to keyway play? Or is it because of a combination of both?
     
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  2. aj481x

    aj481x Member

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    It is because the crank twists and rebounds torsionally at every firing impulse, some more than others. If the damper is tight enough there will be no galling, this is also what causes the cracking in crankshafts. This can also be aggravated by harmonics in the blower.
     
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    Last edited: Dec 31, 2015
  3. TOL

    TOL Active Member

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    So basically it is all to do with the torsional repeated wind/unwind of the crank snout inside the hub bore (due to inevitable key play) and the 300+ lbft massive bolt solutions are really there to just generate enough clamp & friction force to hopefully stop or limit relative rotational movement between the two surfaces?

    Kind of what I figured.

    The spline approach sounds ever better, or at least some other sort of interlocked mechanical design as opposed to just two keys. Maybe even get rid of the hub altogether and design the whole pulley drive deal directly into the shape/design of the crank snout itself?.....

    Thanks.
     
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  4. Cdn526

    Cdn526 Member

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    We had the same problem early on with the A/Fueler, and all we did to remedy it was...after each race weekend, take the damper/timing ring/crank hub off the motor, take it all apart, clean all the components, re-coat w/ nickel never-seize, re-assemble it, & put it back on. Torque to 440 ft/lbs.
    No more problems.
    But I do understand a splined crank is superior, in the no-galling dept.
     
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  5. KEITH CLARK

    KEITH CLARK Member

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    splined crank is the answer, I use a hub with 6 3/16 keys, no lube or Loctite 300 lbs/ft of torque in the bolt, used the same hubs for 10 yrs.
    Velasco and I built the hubs before the splined deal was thought of, the spline is the answer
     
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