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Gears

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by lukers, Nov 5, 2000.

  1. lukers

    lukers Registered Member

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    Could someone please explain the procedure that one does to determine what gears are in the rear. (without removal of the cover) Also how does one check for Posi?
    Turning the driveshaft produces wheel turn of some sort that is different between Posi and others Correct?
    Help

    Luke
     
  2. lukers

    lukers Registered Member

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    Please read me!!
     
  3. nyyef

    nyyef 1/2 ton status

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    you can roll the truck and count how many turns of the diff pinion there are with one turn of the wheel. then match up the closest ratio.

    you can also jack up one wheel count the pinion rotations and multiply by two.

    you can also drive at a steady speed, note the rpm, and calculate it using tire diameter (do not have the formula on hand), there are some tables somewhere that have this info.

    hope that helps.

    Knife.
    knife.coloradok5.com
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    RPM at speed knowing your tire diameter is pretty accurate for finding gear ratio.
    As for whether or not its a posi, you can jack up the axle and spin one tire, with a tight posi both tires should spin in the same direction. With an open diff they will spin in opposite directions. If you have a gov-lock, they will also spin in opposite directions. If your posi is worn they might not spin in the same diection.
    Truly the best way to find out this info once and for all is to pull the cover. Its a good maintenance thing anyways. Who knows there may be water fouling your diff fluid. If you pull the cover off and have a good look at the carrier and gears you'll have your answer and also get to change your diff fluid. Its a small job.
    If you do pull the cover, you'll more than likely see a set of numbers stamped on the edge of the ring gear, on mine it says 41 11. This is ring gear teeth compared to pinion teeth. If you divide the number you get 3.73 to 1.
    You will also see the carrier, If there are 4 spider gears and a cross shaft and nothing else in there it is open.
    If it looks like a cuckoo clock in there its probably a gov-lock.
    HTH
    Rene

    [​IMG]
     
  5. lukers

    lukers Registered Member

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    Thank you all so much. I will pull the cover to check both ratio and diff.
    Luke
     

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