Rear End Noise when Spinning by Hand

Discussion in 'Transmission & Driveline Topics' started by Smiles 79, Aug 23, 2019.

  1. Smiles 79

    Smiles 79 Member

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    Hey all,

    So I set up an Auburn posi with 3.42s from USA Standard Gear in blmy 8.5". When I spin the axle by hand, I get a bit of a clunking noise. Backlash is in spec, the pattern looked good, and everything is torqued down. Any idea what this might be?

     
  2. flht99b

    flht99b Veteran Member

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    Do you have oil in it yet? Sounds dry.
     
  3. Smiles 79

    Smiles 79 Member

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    I've got 2 qts plus some limited slip additive in it.
     
  4. COPO

    COPO Veteran Member Lifetime Gold Member

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    Go do 5 figure 8's in one direction in an empty parking lot and do 5 more going the other way in a figure 8. That will mix the additive for the posi clutches then report back.
     
  5. big gear head

    big gear head Veteran Member

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    NO! DO NOT DRIVE IT LIKE THIS! It has nothing to do with oil additive, clutches or anything like that.

    Is the pinion bearing preload set correctly? Something is not right.
     
    budro6968 likes this.
  6. badazz81z28

    badazz81z28 Veteran Member

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    Yeah, thats exactly how a used rearend I bought years ago sounded like. The crush sleeve was not crushed! lol. You could turn the pinion backwards and it would spin out of the gear.
     
  7. Smiles 79

    Smiles 79 Member

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    Thanks for the responses evrrever. I didn't even have the housing bolted to the leaf springs so I yanked it back out of the car to inspect it tomorrow.

    Could incorrect carrier bearing preload cause this? When I set the diff up I had good backlash, good pinion preload, and a good pattern. I measured the shims and adjusted to get my backlash, but I didn't have to hammer them in.
     
  8. big gear head

    big gear head Veteran Member

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    If you can pull the differential out by hand then it's not tight enough.
     
  9. camaro71/holland

    camaro71/holland Veteran Member

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    There is no pre load on the pinion bearings either, it spins way too easily...
    Did you check this with a torque o meter? Should read 20-25 INCH pound of force with new pinion bearings.
     
  10. camaro71/holland

    camaro71/holland Veteran Member

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    And not needing to tap in the carrier bearings means these are way too loose too...
     

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