9 inch ford

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  • 95rayburn
    Senior Member
    • Sep 2012
    • 162

    #1

    9 inch ford

    Buddy of mine is got a nine inch ford rear end in his late model he's running a 633 gear and gettin like 6300 rpm at end of straight and he's lookin for 1000 more rpm at the end of the straight what gear does he need running a small 1/4 track
    Last edited by 95rayburn; 07-10-2016, 10:33 PM.
  • TheJet-09
    Senior Member
    • Jul 2013
    • 1616

    #2
    I would guess somewhere around a 6.86, but I have no real experience with 9" rearends. I'd hit up some of the old Modified guys and see what they have laying around.

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    • fastford
      Senior Member
      • Dec 2008
      • 4059

      #3
      you use to not get any thing lower than a 6:50 , i think ford racing has some that goes up in the low 7s now....

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      • a25rjr
        Senior Member
        • Feb 2016
        • 3774

        #4
        The old rule of thumb is 100 rpms for every 10 pts of gear. So hes gonna need something in the 7.33 range.
        Turn LEFT, Vote RIGHT!

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        • Work2race
          Junior Member
          • Jul 2016
          • 14

          #5
          6.80 or something close 200 rpm for every 10 points. Keep feeding car up. Less rear weight.

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          • Mr.Kennedy777
            Senior Member
            • Aug 2016
            • 212

            #6
            Remember, just because you're dropping the gear down points your RPM doesn't just got up based on the gear. The torque to wheels goes way up too. This can cause the car to become loose and then your RPMs go waaaay up. I would recommend running a 6.83 to start. (depending on the motor and weight of the car) like jet said. look at what Motive Gear has to offer. 👍

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