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  • Differential help

    Differential help
    I am changing differential ratios. The old one is 3.10 (the jeep is a 2.73, but had to get a rear housing from the junkyard and it is a 3.10, thought I would go ahead and change to 3.73 since I had to rebuild anyway) and the new is 3.73. The old pinion has 45 +5 on it and the new one I got from 4wd hardware says 2.570". The 2.570" could possibly be 2.5 +0" if the plus sign looks like a french 7. The original shim pack is one piece and measures 99 thousanths, the shim pack that came with my kit totals 99 thousanths.
    Just using the +5 and the 0 I am assuming I need to use the original shim pack and add 5 thousanths to it. Does anybody understand my question?

    Last edited by LIG; 12-16-2006, 06:44 AM. Reason: change title

  • #2
    Hey Lig...

    Are you building a Dana 30 front axle or the AMC 20 rear axle?

    Look again at that +5 etch on the old pinion... Are you sure it isn't a sloppy "+3"? A "+5" etch seems a little excessive... I suppose that an etch that high is possible, but would be very rare.

    I think you called it correctly on the "+0" on your new pinion.. That makes sense.

    Those hand-scribed etch numbers can be a real pain, huh?


    • #3
      Differential help

      Thanks for the reply. I called Alloy's tech dept. today. He said to ignore the number on the new one and put back the same shims that came out and it should be right. What do you think?



      • #4
        It must be an Alloy made gearset replacing an original Dana gearset? Trying the same shims may be a decent place to start, but definately check the backlash between the gears and the gear mesh pattern and move it according to that. Did they supply you with a gear pattern chart with your installation kit?