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71 Jeepster Axle Swap Help

Discussion in 'Jeepster Commando and Commando Tech' started by JonAllenTX, Dec 1, 2019.

  1. Dec 1, 2019
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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    Oct 3, 2019
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    19
    Good Morning All!
    I am working on restomodding a 71 Jeepster with my 9 year old son. It will be his first vehicle in 6 years. I was planning to upgrade the front axle to a CJ narrowtrack with disk brakes and regearing to something better than the 3.31 ratio the Jeepster came stock with. Exact ratio is undecided, but was leaning towards something in the 3.73-4.10 range.

    That was until a buddy of mine from our local Jeep group who is rebuilding a 64 J200 Gladiator offered up his axles and driveshafts once he upgrades in a month or two. While it's still drum brakes all the way around, this allows me to upgrade to D44 front and rear, already geared to 4.27 and widen the stance without needing wheel spacers. Found a drum to disk kit for $700, which isn't any more expensive than regearing (since that I would probably have a shop do) if I found a CJ narrow track and the axles would be free from the start vs having to buy a narrow track. I presume the driveshafts are out as they're too long. From what I've heard they're not much of an upgrade anyway.

    Anyone know what would be involved in getting the FSJ axles to work under the Jeepster? Trying to weigh pros and cons between both options. My understanding, which could be wrong, is that the narrow track would be bolt on. So it'd be much easier and straight forward. For the FSJ axle, I'm not a welder, but lots of folks with those skills have been eager to help with the project.
     
  2. Dec 1, 2019
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
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    7,835
    I'd pursue your original idea...the narrow track axles.
    A closed knuckle front 44 is not really that desirable in my opinion.
    And the rear 44 will be hard to find replacement axles for if you break one.
     
  3. Dec 3, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    Aug 10, 2003
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    JMO - J-truck axles are absurdly wide for a CJ or Jeepster. Plus the early Gladiator axles have coarse splines (10?) on a tapered rear axle - weak - and a closed-knuckle front axle. The J-truck axles would be thrown away by most builders, unless it was for a factory original restoration.

    If you don't want to regear, I'd suggest some axles from a '72-75 CJ-5 or CJ-6. These are an open Dana 30 front and flanged Dana 44 rear, 11" drum brakes, and came with 3.73 ratio standard from the factory. The front will bolt in, but you will need to locate the rear spring pads outward to accommodate the outboarded rear springs on the Jeepster. Axles from a '76 or newer CJ may have the correct rear pad width, but the rear axle from '76-on is the much less desirable AMC 20 (Corporate axle) which has weak tubes and weak 2-piece axles. They can be upgraded with a truss and aftermarket axle shafts, but I think you'd be better off with the Dana 44 and new pads. These newer axles are typically geared taller too; a scarce few with 4.10s but most will be 3.54 or taller.

    A '71 should already have a flanged Dana 44 rear axle. You could regear that axle and install an open Dana 30 from a '72 or newer CJ in the front.

    Which transmission do you have?
     
    Last edited: Dec 3, 2019
    RATTYFLATTY likes this.
  4. Dec 3, 2019
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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    Thanks Tim. You've been quite helpful on a few of my posts thus far. Certainly a wealth of information.

    Let me ask you this, another buddy has a widetrack D30 from a CJ along with an AMC20 rear. He had both rebuilt 10 years ago and have 5k miles on them and he modified the 20 to solid axles. He doesn't want to separate them, but will sell both for $500. Based on what I've found that's cheaper than disk conversation or regearing and it would alleviate both. I know the AMC is less desirable, but from my reading it's mostly due to the two piece axles which has already been remedied. Is this a better route and/or worth the price?

    Btw I have a TH400 transmission.
     
    Last edited: Dec 3, 2019
  5. Dec 3, 2019
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    Oct 23, 2007
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    Also keep your eye's open for a 72 or 73 Commando. They are a direct bolt in 30/44 combo. They didn't come with disk brakes up front but 3.73 gears were common.
     
  6. Dec 3, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    NP! Glad I could help.

    Ratio? A 20 with 1-piece axles sounds like a reasonable option, and $500 for the pair seems fair. If you want wider axles, these will be wider. I think the pads on a CJ 20 will line up with the rear Jeepster springs. I ask about the transmission because a 4-speed conversion would be an alternative to the axle swap with deeper gears, but not so straightforward with the TH400.

    Wagoneer axles are another popular choice, but they have even taller gears than your Jeepster axles, typically.
     
    JonAllenTX likes this.
  7. Dec 3, 2019
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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    I'd have to ask him again, but I think he said 4.09 or 4.10 for the ratio. 4.09 is in my head, but seems like an odd ratio.
     
  8. Dec 3, 2019
    OzFin

    OzFin Vintage Jeep Guy

    Michigan
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    Jul 16, 2007
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    528
    If they are in the 4:10 + or - range I would go for them, $500 for the pair in good condition is very fair.
    The upgraded AMC 20 should hold up fine unless your son learns how to do hole shots on dry pavement or other similar abusive activities.

    I put in a D30 & D44 with 3:73's from a 74 CJ5 in my 70 C101 J/C and run 30x9.50 tires on 8" wide wheels and it is a nice combination ( I have the 3 speed T-14 transmission).

    You would be able to run 31's with a small lift with something in the 4:10 range, if you wanted to.
    [​IMG]

    Running stock 28" tires with 4:10 would give lots of low end power but you may not want to run at sustained hi-way speeds with that combination.
    There are several online calculators that you can plug in various gear ratio's / tire combination's to check engine RPM's at various speeds.
    Here is an example Engine RPM Calculator | Spicer Parts
     
  9. Dec 3, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    Axles with 4.09 and 4.10 ratio both exist. Just depends on the size of the ring and pinion and the tooth ratio that's chosen (ie 41/10 = 4.10, 45/11 = 4.09). It is possible to have 4.10s front and 4.09s rear; close enough to be considered matched.
     
  10. Dec 4, 2019 at 9:37 AM
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
    Joined:
    Oct 3, 2019
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    Oz thanks for the chart. That's a useful reference. The plan is definitely a lift and larger tires. Either 2" with 30" tires or 4" with 31s. TBD, I'm letting him decide. We're a pretty short family so I don't want to go too crazy. I really like the look of the 4" with 31s that I've seen. My JK Wrangler is stock ride height with 32s and most of the family, except me, has trouble getting in. Obviously, my son will grow by the time he's 15-16, but has very little chance of being any taller than I (his Mom is 5' even, sister is expected by the Docs to be about the same, maybe a little shorter and both Grandfather's are both under 5'6. I'm the "tall" one at 5'7).

    Tim, thanks for the info. Hadn't heard of 4.09 before. Thought it was odd just because it was so close to 4.10.
     

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