Differential humming...(video)

Discussion in 'Transmission & Driveline Topics' started by willem, Dec 15, 2017.

  1. willem

    willem New Member

    13
    0
    Nov 6, 2017
    IMG_20170610_200138.jpg IMG_20170610_200145.jpg IMG_20170610_200153.jpg



    So we installed a new posi and gear ratio (3.73) on the 8,5 GM.
    Everything has been fitted and torqued according to specs. But I must have missed something because i have a sharp whizzing/humming sound at around 2000rpm in 3rd gear (TH350) when im cruising around 75kmh with MINIMAL amount of gas. As soon as i let go or increase gas, the noise fades and stops. you will hear it in the video.

    now i've been looking into other things as well, such as alignment of driveshaft axle etc.. it could be we didn't put it back together correctly

    Anyone can help me out? some advice or insights? similar experience?

    thanks
     
  2. Blown Camaro

    Blown Camaro Veteran Member

    1,000
    39
    Dec 13, 2009
    Deltona, FL
    I have had this before on a 12-bolt and a Ford 9". Both times it was pinion bearing preload. I retorqued the pinion nut and it went away. Maybe you did not crush the sleeve enough?
     
  3. big gear head

    big gear head Veteran Member

    5,888
    17
    Jul 30, 2001
    Central City, Ky.
    Something in the rear end was not set up correctly. Either you didn't get the bearing preload set right or the pinion depth or backlash is off. Don't drive it anymore until you get it fixed or you will ruin the gears.

    Can you give some details about how you went about setting up the gears? How did you set the pinion depth, bearing preload and backlash? Did you take any pictures of your contact pattern?
     
  4. badazz81z28

    badazz81z28 Veteran Member

    14,177
    110
    May 4, 2001
    Las Vegas, NV
    Sound the same as my 9" moser set up and they told me pinion angle....
     
  5. willem

    willem New Member

    13
    0
    Nov 6, 2017
    ill post the technical specs this week-end.

    pinion angle? You mean the axle is sitting too high or too low?
     
  6. big gear head

    big gear head Veteran Member

    5,888
    17
    Jul 30, 2001
    Central City, Ky.
    I very seriously doubt that the pinion angle has anything to do with this. Either the gears are bad or something isn't set correctly in the gears or bearings.
     
  7. camaro71/holland

    camaro71/holland Veteran Member

    883
    18
    Aug 27, 2003
    The Netherlands
  8. badazz81z28

    badazz81z28 Veteran Member

    14,177
    110
    May 4, 2001
    Las Vegas, NV
    I sure wish Moser saw it this way
     
  9. big gear head

    big gear head Veteran Member

    5,888
    17
    Jul 30, 2001
    Central City, Ky.
    It's a shame when a company gets too big to give the personal help that their customers need, or something happens to the company founder. If Greg Moser were still running things then it might be a different story.
     
  10. willem

    willem New Member

    13
    0
    Nov 6, 2017
    sorry for delay
    pinion depth 4,260''
    pinion bearing preload between 20 - 25 in-lb
    backlash 0.009''

    anything you can tell me about these numbers?
     

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