Set-up Bearing: BGH Was Right

Discussion in 'Transmission & Driveline Topics' started by berg2695, May 30, 2019.

  1. berg2695

    berg2695 Veteran Member

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    I made the new Timken pinion bearing in my installation kit into a set-up bearing. I achieved what I thought was a pretty decent pattern. Then I installed a brand new identical bearing for final assembly. Well, the new pattern is way too deep (I think). Now I have more work to do. I will say this: This is my first gear set-up and the set-up bearing allowed me to quickly get some experience moving the pattern around. However, I did NOT get lucky when I replaced it with the final assem. bearing. This is the usual 8.5" 10-bolt, new 2.93 AAM gears. Am I on the right track?
     

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  2. camaro71/holland

    camaro71/holland Veteran Member

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    Must say that your drive side pattern looks quite decent, although very hard to see/read on your picture. And it looks like it's running of the tooth on the toe side?

    Coast side is definitely too deep, but the difference in pattern (reasonable and deep) between both sides is quite big...
     
  3. berg2695

    berg2695 Veteran Member

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    Both pictures are drive side pictures. One with a set-up bearing and one with a new unmodified bearing. I didn't really make that clear in my post. I've relabled the photos. I just found it interesting that there could be such a big difference with the same pinion shim. So, do you think the first pic shows a decent pattern?
     
  4. camaro71/holland

    camaro71/holland Veteran Member

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    My bad. Wasn't looking close enough on my phone and assumed (there you go...) it was the coast side.

    First pattern looks pretty close, but fairly low (toe side). You don't want it to run off the tooth. What was the backlash on that setup?
     
  5. big gear head

    big gear head Veteran Member

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    Is the AAM gear a 2 cut or a 5 cut gear? Many of the AAM gears are 2 cut, so you may need to tighten up the backlash. You may already be aware of the differences in the 2 types of gears, but the set up is a little different between them.
     
  6. berg2695

    berg2695 Veteran Member

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    The pinion shim and backlash are printed on the pictures. It's a 5-cut gear. (Heel of the tooth is taller than the toe, right?) I will change the pinion shim and repost. The factory 3.42 gears came with a .039 shim. Thanks for helping me out you guys.:)
     
  7. big gear head

    big gear head Veteran Member

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    Yes, that should be a 5 cut gear.
     
  8. cadillac_al

    cadillac_al Veteran Member

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    I'm surprised there is that much difference in new Timken bearings. I guess the factory tolerances aren't that close. Maybe the new one isn't on all the way?
     
  9. camaro71/holland

    camaro71/holland Veteran Member

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    I never have used setup bearings. What I do everytime with regular bearings , is pressing them on till the same amount of force on the manometer on the press. If it makes sense.... this way I make sure they're all seated the same way.
     
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  10. berg2695

    berg2695 Veteran Member

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    I tried to make sure the race was completely seated. I'll double check it anyway. I'm thinking it may have something to do with compressing a multiple layer shim pack. A few foot- pounds of torque with the pinion nut (set-up bearing) versus many hundreds of pounds of compression with a press.
     

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