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Franken-commando???

Discussion in 'Jeepster Commando and Commando Tech' started by Robert Wight, Jan 17, 2021.

  1. Jan 17, 2021
    Robert Wight

    Robert Wight New Member

    Houston, Tx
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    Jan 5, 2021
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    So, earlier I introduced my 73 Bullnose Commando in the VIN forum...
    Spent the last few days poking around and investigating, have determined the driveline has been replaced.

    She does have the AMC 304 V8, but the rest appears to be different.
    Tremec T176 4-speed transmission
    Dana 300 transfer case
    AMC 20 rear axle

    and, I think a Dana 30 front axle. I'd like some help in confirming....
    The cover appears to be consistent with either a Dana 27 or a 30. There is a 30 cast into the top of the diff housing. The metal tag appears to say "3.31 43 13" and "5363734" in two rows (though somebody painted the tag...).

    There appears to be a port for a breather vent in housing, just right of top dead center if looking at differential cover, though the vent is plugged with a piece of wood painted black....(INSPECT THOSE USED VEHICLES!!!).
     

    Attached Files:

  2. Jan 17, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Can't imagine anyone swapping in a D27 into something later unless there was absolute budget necessity....If the steering knuckles are open style, then you most likely have a D30...if they are closed knuckle then you might have a D27.
     
  3. Jan 17, 2021
    Robert Wight

    Robert Wight New Member

    Houston, Tx
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    As a 73 Commando, She should have a Dana 27, the 30 would be a change from factory.

    please expand on open vs closed knuckles, how do I tell by inspection?
     
  4. Jan 17, 2021
    Robert Wight

    Robert Wight New Member

    Houston, Tx
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    Found the knuckle type, open knuckles.
     
  5. Jan 17, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    I thought the D27 was last used in 1971 in the cj5...not 100 percent sure about the jeepster line, but thought all amc era stuff went D30. Open knuckles would be D30.
     
  6. Jan 17, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Front axle should be 535xxxx, a model 30 in the '73 Commando. Open knuckle is a 30. I don't have a book that overs '73 but they are out there.

    43 13 is 43/13 = 3.307 or 3.31 ratio. This is reasonable for a Commando. Make sure the rear matches the front before you engage 4WD.

    A Corporate 20 rear (M20) is a reasonable swap for a Commando, since the spring pads line up. There is nothing major to prevent an '80-up drivetrain from a CJ to be swapped in to a Commando. Jeep never offered the T-176/D300/M20 combo in the Commando, but it was offered in the '80-up CJs.
     
  7. Jan 17, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    No, every '72-73 Commando came from the factory with an open knuckle Dana 30 front axle.
     
    FinoCJ likes this.
  8. Jan 17, 2021
    Robert Wight

    Robert Wight New Member

    Houston, Tx
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    Thank you for the help.

    Another question, the Dana 300 (or typically all transfer cases) have a 1:1 output ratio between the front and rear driveshafts, correct? I’m going to jack up and count tire to driveshaft rotations, that would suck for there to be a reduction in the transfer case between the two outputs.
     
  9. Jan 17, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    as long as the TC is in high range, it should be 1:1 - and of course its the same for both the front and rear if in 4wd hi range.
     
  10. Jan 17, 2021
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    5363734 tag would be for a 1982 and later CJ, 3:31 ratio FYI.
     
  11. Jan 17, 2021
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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    Jun 24, 2004
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    If you are looking to check gear ratio's, do your self a favor and drop the covers and do a tooth count. This will give you a chance to inspect the ring and pinion, carrier for damage, and refill the pumpkins with fresh oil.
     
  12. Jan 17, 2021
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    Your D300 has a high range ratio of 1:1 and a low range of 2.62:1. You can't have any "mixed" ratios; either 1:1 high range for both front and rear outputs, or 2.62:1 in low range for both front and rear outputs
    The transfer case has two shift rails. One controls high or low range, and the other controls rear only (2WD), or both front and rear outputs (4WD).
    -Donny
     
  13. Jan 18, 2021
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    My 70 Commando has a 27 front axle.
     
  14. Jan 18, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Yes...but I assume it went to a D30 in '72 like the cj5....the OP has a '73.
     
  15. Jan 18, 2021
    jackdog

    jackdog Member

    Finger Lakes NY
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    Jul 16, 2013
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    70 1/2 and 71 Commandos had the D27 set up for Saginaw steering. 72 and 73 D30 open knuckle.
     
  16. Jan 23, 2021
    Robert Wight

    Robert Wight New Member

    Houston, Tx
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    After a busy day, I have confirmed both axles have a 3.07 ratio. Both have a 43 ring, and a 14 pinion

    The front D30 now has a tapped brass vent routed by the battery box.

    Tomorrow will be installing tail lights and working other electrical issues.
     
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