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Rear Diff

Discussion in 'Early CJ5 and CJ6 Tech' started by FD Engine 1, Apr 23, 2018.

  1. Apr 23, 2018
    FD Engine 1

    FD Engine 1 New Member

    Tennessee
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    I’m about to start on 67 CJ5. I’ve been looking at chassis on other build threads. Most seem to have tc output on pass side, lined up with offset rear diff. Here my D18(I think, correct me if I’m wrong) & center stump Dana 44(again, I think). Should my drive shaft be running so crooked? Rear has 11” drums if that’s useful information.
     
  2. Apr 23, 2018
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    Looks like someone put a 72-75 centered rear axle under your Jeep. Not optimal at any speed. Easily remedied by swapping in a 20 transfer case. Best to pull the diff covers and double check what gear ratio is in them and make sure they match.
     
    Twin2 and 47v6 like this.
  3. Apr 23, 2018
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    You've probably got a centered D44 from a later jeep (that would have run a D20). Your D18 would prefer a offset rear axle. Offset tapered 44s are pretty common - the offset flanged ones are not.
     
  4. Apr 23, 2018
    duffer

    duffer Rodent Power

    Bozeman, MT
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    What Daryl said. It would also appear you have an open knuckle front axle, which, if from the same donor Jeep, is probably a D30. That makes it likely the gear ratios are the same. Realize, if you swap in a D20, your low range goes from 2.46:1 to 2.0:1 but it is possible to swap in lower gears.
     
  5. Apr 24, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Let's look at the front axle. Also tell us the gear ratios of the front and rear axle.
     
  6. Apr 24, 2018
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    If you were closer, I would give you an offset tapered axle for it. I have several around here with varying ratio's.
     
  7. Apr 24, 2018
    aekdbbop

    aekdbbop Member

    TN
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    Had the exact situation from the previous owner. Switched to an offset d44 and everything is good. :)
     
  8. Apr 24, 2018
    FD Engine 1

    FD Engine 1 New Member

    Tennessee
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    So my options are switching to D20 or offset D44. Show of hands, which would y’all do?
     
  9. Apr 25, 2018
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    Offset rear diff.
    The 18 tcase has disadvantages, most notably being noisy and prone to leaks, but offers a lower low range, better driveline angle, and most importantly, the ability to add an overdrive.
     
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  10. Apr 25, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Depends on which front axle you have. Also on whether the ratios match. Need more data.
     
  11. Apr 25, 2018
    Keys5a

    Keys5a Sponsor

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    Swapping to an offset D44 would likely be easier and cheaped. You just need to match gears to what's up in the front diff.
    -Donny
     
  12. Apr 25, 2018
    rejeep

    rejeep Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Rochester, NY
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    you can get a fancy driveshaft..
     
  13. Apr 25, 2018
    jeep2003

    jeep2003 Well-Known Member

    Upstate NY
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    If you dont have vibrations leave it alone it seems to be a good combo.
     
    ITLKSEZ likes this.
  14. Apr 25, 2018
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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    What is your final goal for the jeep?

    I'd leave it alone if it's just for weekend ice cream runs if you don't notice any bad vibrations. Keep an eye on your u-joints because they'll probably wear out a little quicker than usual.

    Option 2 - Swap to an offset rear if you can find one with matching ratios. The ratios are more than likely 3.73s which won't really benefit from an overdrive anyway, so...

    Option 3 is swap in a Dana 20 t-case. You'll lose a bit of crawl ratio, but it will still be fine for 99% of what you'll encounter on stock tires.

    Again, make sure your front and rear ratios match before you decide on anything. Gear swaps can get expensive.
     
  15. Apr 25, 2018
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    lots of good information here on that drive shaft alignment
    it's possible that the front and back came from same jeep
    something you would have to check . ratios

    something to consider is do you want to hook up the rear brake shoes for the parking brake
    then swapping to a D20 would be my choice
     
  16. Apr 25, 2018
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    If the axles match it would be best to go with a 20. The gear ratio difference between an 18 and a 20 is so tiny that it is completely unnoticeable other then on paper by people that love to figure out crawl ratios.
     
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  17. Apr 25, 2018
    FD Engine 1

    FD Engine 1 New Member

    Tennessee
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    Tons of good info. Thanks. I’ll definitely check the ratio to make sure they match. ITLKSEZ probably nailed it with the weekend ice cream run. I’ll probably run it like it is if ratios match, and keep my eyes open for D20 in the future.
     
  18. Apr 26, 2018
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    Would a D-300 TC be in the running as an option?
     
  19. Apr 26, 2018
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

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    The only bolt-in option for a D300 is one from an '80 Scout (if the bull gear is even compatible?), and they're as rare as hen's teeth.
     
  20. Apr 26, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The D300 is a good choice, but not an inexpensive choice. There were very few made that have the right pattern ("texas" pattern) to mate to the OP's existing transmission, and they are not available inexpensively. Most D300s have the circular New Process pattern, which either requires an expensive adapter or a transmission swap. A '67 should be either a T-90 (with the F134) or a T-86 (with the 225). Both of those will bolt up to the D20 using a 6-spline D20 input gear. Pick the right gear from this chart: The Novak Guide to Dana 18 & 20 Gears Interchange 1941-1979
     
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