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  • New axle gearing question

    I need some input on what gearing would be best for my 81 CJ7, AX15 transmission, and 32.1" tires (275/65R18). Using the Cummins calculator, I'm thinking 3.54 gears would be the best balance for my CJ. Has anyone built something similar with different gearing? I am looking at ordering new D44 axles from East Coast Gear Supply in the next couple days. Thank you for any info you care to share.

  • #2
    Not sure if you have solved this but you are prolly ok with a 3.54. Somewhat depends on what you will be doing with it and how much it weighs tho.

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    • #3
      Can you get a Dana 44 with 3.54? I thought the Dana 44 stopped at 3.73. Please let me know as this may have me looking at Dana 44s as well. I'm running 3.07s with my AX-15, with 33s ie 32.8" and it's great on the highway. Off-road I'm going way too fast so I'm going to need to grab either a really low 2 speed tcase or get some sort of 4 speed tcase.

      I feel like 3.54/3.55 is the best way to go. I honestly think the D44 is overkill, btw but they're great any way, but often you could find a high pinion Dana 30 with stock 3.55 gears for $100-$200. Dana 35 can be found pretty similarly priced or free if you're still running leaf springs and that'll be with 3.55s.

      I've been looking at going with some "super" kits and lockers and from the guys that try to break their stuff, the Super kits are good up to 33 in tires and most claim they're good for 35" tires as long as you're not hopping the axle hard, which will break most axles.

      Follow up though what you figure out what you want to do because I'm in a similar boat.

      Oh 8.8s are cheap as well, but don't let some guys know as some guys seem to really not like them. I can't remember the reasoning, but I do think they prefer to build other axles over the 8.8, but a stock one with 3.55s, there's a lot of options out there for cheap.

      Just remember we're talking about a diesel so a lot of US guys think they can't get over a bump without revving to 4,000 RPMs.
      Last edited by DieselJeep; 05-29-2019, 02:15 PM.

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      • #4
        I ended up ordering new bolt-in axles front and rear from East Coast Gear Supply a couple weeks ago. I went with 3.54 in both and set up for YJ springs.

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        • #5
          Are you running a locker for that axle? I got curious and just selected what I would order if I was to get a Dana 44, but I had always seen only 3.73 and above for those axles.

          I'll probably just keep my Dana 35 though and just go to 30 spline 1541 axles, which is actually a bit stronger than the stock Dana 44, which is plenty for my needs. All day long people want to get rid of the Dana 35 used on a bunch of vehicles and with 3.55s which is what I want too, but those don't work on the TJ without some fabricating.

          In any case you'll be happy with the 3.54s. I'm pretty happy with 3.07s and 33s, but there's a few speeds on windy and hilly roads that cause me to shift more than my liking, to the point that even 3.73s wouldn't be terrible, but then that would eat into how much I like 3.07s on the highway. My plan is to go to 3.55/3.54 and if I'm towing extensively to swap my wheels out for some with 31s.

          Unfortunately those options, with my stock 2.72 t-case I'm going too fast off-road and I find myself spinning my tires way too much, so I think I'm going to swap out to a 5:1, but I'd love the option for 1:1, 2.72:1, 3.8:1 and 10.3:1. The biggest downside for the 4 speed would be the extra lever. Seems like it would be pretty crowded.

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          • #6
            Just saw this... you probably already have your gears and set up, it may even be running by now! I built my CJ with AX15, 33's (really about 32") and 4.10's. It was too low for my use so I swapped in 3.55's. They work well but my CJ has a 4.5" RE lift, so pushing all that air over 65 is a challenge. Reality is 5th gear is good for 60 and above but really it's comfy at 65 to 70+. I will probably go to smaller tires and lower the jeep back to near stock sometime in the future.

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            • #7
              Originally posted by jeepCJ7 View Post
              Just saw this... you probably already have your gears and set up, it may even be running by now! I built my CJ with AX15, 33's (really about 32") and 4.10's. It was too low for my use so I swapped in 3.55's. They work well but my CJ has a 4.5" RE lift, so pushing all that air over 65 is a challenge. Reality is 5th gear is good for 60 and above but really it's comfy at 65 to 70+. I will probably go to smaller tires and lower the jeep back to near stock sometime in the future.
              I don't mean to hi jack here, but I keep debating the 3.55 and 3.73s with my 33s. I could see running 31s occasionally, but 35s seem like there's too much stuff that's needed with my setup. I'm still running my stock axles and 3.07s right now and I can't stop working on my tractors long enough to save up or even have the time to do anything with my axles.

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