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Differential Gear Swap Pattern Check

Discussion in 'GM Powertrain' started by ippielb, Nov 5, 2011.

  1. ippielb

    ippielb Active Member 1000 Posts 100 Posts

    Just curious to see if anyone knows if this is an acceptable pattern.


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    Let me know.
  2. 2COR517

    2COR517 New Member 1000 Posts 100 Posts

    Looks like the pinion isn't quite deep enough. What's your backlash spec? .015" sounds like a lot.
  3. ippielb

    ippielb Active Member 1000 Posts 100 Posts

    This is my base set up. I'm going from here, i will try to reduce the shim on the main bearing. Once i get pinion depth i'll go after backlash, i do not know what the spec is suppose to be on the gears, i cannot find it anywhere in the book they supplied. My gears are USA Gear, in a green box.
  4. LURCH

    LURCH New Member

    I was thinking .007/.009 and I agree on the pinion depth.
  5. 2COR517

    2COR517 New Member 1000 Posts 100 Posts

    You need MORE shim under the inner pinion bearing. That will push it towards the center of the ring gear.
  6. ippielb

    ippielb Active Member 1000 Posts 100 Posts

    Here's what i got now, 0.007 backlash.

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    And the pattern seems more rounded and centered. I can say I'm happy with this pattern. Does seem like the pinions too far out on the drive side though.... Coast side is perfect.

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  7. ippielb

    ippielb Active Member 1000 Posts 100 Posts

    I got ambitious and changed the pinion depth...


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    Let me know what you think, tomorrow i'm sealing it all up.
  8. TRPLXL2

    TRPLXL2 New Member Platinum Contributor 1000 Posts 100 Posts

    Very interesting post here, I learned something new today! My dad is very old school as he used to take a piece of newspaper and roll it through the gears, he would make his adjustments based on how the paper came out....
  9. 2COR517

    2COR517 New Member 1000 Posts 100 Posts

    Looks good to me. Just curious, did you use a setup bearing for the inner pinion?
  10. ippielb

    ippielb Active Member 1000 Posts 100 Posts

    I re-did it again and got basically the same pattern with 0.005"-0.006" backlash, so i'm going to stick with that.

    I took a brand new bearing and bored out the inside so that it could slip on and off. The bearings from my rebuild kit from stock differ in size and angle. So i couldnt use the stock bearing for set up. Had to buy a whole new bearing. Well worth the $30.

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