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3.21 gears in 14bff?

Discussion in 'The Garage' started by KevinsK5, Mar 24, 2006.

  1. KevinsK5

    KevinsK5 1/2 ton status Premium Member

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    I was looking at some factory chevy pickup brochures ('74 and '76) and there is a spec list on the back cover for engines/transmissions/ratios etc. According to these spec sheets a 3.21 ratio was available for the full floating axle (14 bolt) but ONLY in the regular cab C20. Has anyone ever seen a 14 bolt with 3.21 gears? Thanks, Kevin
     
  2. tarussell

    tarussell 1/2 ton status

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    Yep !

    Tom
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah, as a matter of fact I think I've got a set of 3.23 gear's from the front of a truck that was so equipped...

    3.23/3.21, ring/pinion count isclose enough that either of those numbers is interchangeable.
     
  4. IDGMC

    IDGMC 1/2 ton status

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    Ok. you got me nervous now. I got a set of 3/4 ton axles. When I spun the tire and counted rotaion/driveline rotation...it didn't seem right. So then we pulled the covers and counted teeth. The front figured to be 4.10...and the rear well with a gov-lock in it it was hard to see the pionion but i think 4.11. Why if I spun the tire would I end up with a higher gear ratio? FREE WHEELING?
     
  5. KevinsK5

    KevinsK5 1/2 ton status Premium Member

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    Remember when checking gear ratio on an open diff to only raise ONE tire off the ground. Count the rotations of the driveshaft and multiply the # of driveshaft rotations by 2 to get the ratio. For a 4.10 open, the driveshaft should rotate 2.05 times for every one turn of the wheel that you have off the ground. You don't do this with lockers or posis, for those raise BOTH tires and spin em once, the pinion will give actual ratio without multiplying by 2. For 4.10's, the driveshaft will spin exactly 4.10 revolutions to every one of the tire. Kevin
     
  6. 79k20350

    79k20350 3/4 ton status

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    x2, or if you cant do math rotate the tire 2 times;):rolleyes:
     
  7. KevinsK5

    KevinsK5 1/2 ton status Premium Member

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    Or you could do that!! :D :D
     
  8. beater_k20

    beater_k20 Banned

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    no need to be worried, with 4.10/4.11 you're safe. hell, if you had 4.09/4.11 you'd be good.
     
  9. u2slow

    u2slow 1/2 ton status

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    I picked up a 3.21 14bFF for my Burb to get some highway legs. I believe it was from a mid-70s C20 with a BBC.

    I got a 3.23 10b front from an '80 K20. It would have had the 3.21 14bFF for the rear.

    My Dad also has the 3.21 in a '79 C20 crew (BBC as well.)
     

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