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12 bolt gear pattern

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MA87K5, Dec 5, 2006.

  1. MA87K5

    MA87K5 1/2 ton status

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    I am trying to set up my 12 blt rear. I claculated center line by measuring the space between the carrier bearing cap flange and the race bottom. Then I meassured the carrier bearing race outer dia and divided by 2 to get the center. Then I subtracted the flange meas from the race center and came up with a diff of .040. I talked to Richmond gear and they told me to divide the .040 by 2 and then sudtract from the pinion depth etched on the pinion to find the correct depth. Is that correct. If so then I have the pinion depth set at .001" from the depth calc. B/L is at .008

    IMG_4054.JPG

    IMG_4055.JPG
     
  2. bigblock72

    bigblock72 1/2 ton status Premium Member GMOTM Winner

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    Good job! Looks like a textbook pattern to me, time to button it up and go break them in.
     
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Nice , mine looks like this , and they are broken in now and pretty quiet . Nateinchandler set this rear in my garage .

    IM000278.jpg
     
    Last edited: Dec 6, 2006
  4. 1977k5

    1977k5 3/4 ton status Vendor

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    The garage would be a better place to get replies for this.

    Having said that, I have setup a lot of gears and I would undoubtedly run that pattern. Good job :D
     
  5. MA87K5

    MA87K5 1/2 ton status

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    thank you everyone.
     
  6. MA87K5

    MA87K5 1/2 ton status

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    the rear is in the truck and drove for about 5 miles and I heard just the tire noise. So far so good. Richmond says break in is 10 miles rest for 30 min, do that for 2-3 times. After that (for towing) 200-300 miles rest for 30. Crossing my fingers.
     
  7. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've gotta ask, why didn't you use a dial guage to take actual measurements rather than calculate and hope that was how it ended up?
     
  8. 1977k5

    1977k5 3/4 ton status Vendor

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    Gear sets are made in such a way that the manufacturer knows how far the pinion needs to be from the centerline. If you have the tools to measure that distance, you can set the pinion depth to the specified number and it should be perfect (setting pinion depth is the most time consuming part of setting up gears).

    Bottom line is that it saves time.
     
  9. MA87K5

    MA87K5 1/2 ton status

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    I did use an electronic caliper. I didn't guess at the measurements. I don't have the pinion depth tool like the one pros use. It's bad enough that it took me 2 weeks on and off to finish the job. This was my first complete diff I ever did. I asked for help before and no one could give me the info I needed.

    http://coloradok5.com/forums/showthread.php?t=189493
     
  10. MA87K5

    MA87K5 1/2 ton status

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    Well, I went offraoding and had no problem with my rear. If anything the posi kept me from getting stuck in a water/mud/ice hole. So I am happy that I did the rear myself. Saving me hundreds. Just hope I never have to again but if I do it will be a little easier.

    IMG_4064.JPG
     
  11. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Good on ya!:waytogo:
     

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