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Unknown 14BFF gearing

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by punchdrunk, Oct 20, 2001.

  1. punchdrunk

    punchdrunk Registered Member

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    I found a 14BFF cheap, Is there an easy way(for the inexperianced) to determine the gear ratio and if it's an open carrier, there is no tag and the rearend is out of the truck?I would appreciate any help,this site is great!!

    Doug Martin
    Santa Cruz CA
     
  2. MudFrog

    MudFrog 1/2 ton status

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    Best way would to be to pop the cover of the diff. The gearing would be stamped on the ring. I don't remember all the codes but for a 4.10 gear set the stamp would read soemthing to the effect of 41 10. 41 divided by 10 would be 4.10. So you can figure it out based on that.

    89 K5 Silverado
    <a target="_blank" href=http://mudfrog.rockcrawler.com>http://mudfrog.rockcrawler.com</a>
     
  3. K5RON

    K5RON 1/2 ton status

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    For an open carrier, if you spin oone drum, the other will either stay put(brakes dragging) or turn in the opposite direction. A locker or LSD will turn in the same direction. Even better yet, turn the pinion and watch the direction of the drums.

    For gear ratio, count the teeth on the pionion and count the teeth on the ring gear. Divide the pinion number into the ring gear number and WALLA there's your ratio!


    Ron


    '84 K5......Tree Fitty, SM465/Np205, D44/14BFF, Pro-jection! .....and of coarse no other color than Odie!
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    There are two real possibilties carrier wise. It will either be open or have a gov-lock is it is stock. Both will allow the opposite wheel to turn backwards...
    The carrier on a 14 bolt FF is a 2 piece affair and the cross shafts can be seen between the halves if you spin the carrier. An open diff would have four shafts (it's actually one big cross) that can be seen. The Gov-lock has three.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  5. punchdrunk

    punchdrunk Registered Member

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    WOW,thanks for the info,I'm 99% sure its stock.so if i spin the pinion and the drums spin the opposite way its an open carrier?was the gov-lock the only factory option on a mid 80s chevy 14 bolt
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Just remove the cover. You'll want to change the fluid anyways later and with the cover off you can verify the ratio for sure. Both the open dif and the gov-lock will do the same thing if you spina drum...the other side should spin opposite. So spinning a drum just verifies that it spins...[​IMG]

    The numbers to look for are stamped on the edge of the ring gear, as stated by someone else earlier. Look for 4 shaft ends sandwiched between the two halves of the carrier, that will indicate an open diff.

    common ratio's are 3.73, and 4.10 so most likely you will find one or the other. Military 14's usually came with 4.56, and the occasional 2wd 14 came with 3.23's, but that seems pretty rare.

    3,73's = 41 to 11
    4.10's = 41 to 10
    4.56's = 41 to 9

    41 is the number of teeth on the ring gear and 9, 10, or 11 is the number of teeth on the pinion gear.

    Rene

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  7. punchdrunk

    punchdrunk Registered Member

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    Thanks Rene,I got it now.is the gov-lock the only option from the factory on the 14 bolt?

    Doug
    <P ID="edit"><FONT class="small">Edited by punchdrunk on 10/20/01 06:48 PM.</FONT></P>
     
  8. White Knight

    White Knight 1/2 ton status

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    Jack up the truck or lift the axle off the ground and spin the tire/drum and count the revolutions of the pinion yoke, 1 turn on tire 4+ turns on pinion=4:10 as this isn't a exact science it will help and you don't have to pop the pumpkin cover

    Still a very pissed-off
    White Knight
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Military 14 bolts got the Detroit locker...Civi 14's were open or Gov-locked.

    Rene

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