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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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    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
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    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.
     
    fhoehle likes this.
  3. Dec 3, 2019
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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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
    fhoehle and RATTYFLATTY like 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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    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 2020 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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    585
    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 2020 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
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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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.
     
  11. Apr 18, 2020
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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    Hey guys, hate to resurrect this thread, but had a few quick questions. I'm about to pull the trigger on this thing. I ended up stripping the frame down completely to clean it up and recoat it. So, my axle swap and lift came into play a little earlier in the process than I'd antiscipated. Seems like wasted effort to bolt up the old axles and suspension since I've stripped the frame down completely. I'm going to be swapping out the axles with the ('78) CJ7 Dana 30 and AMC20 I'd mentioned before. They've been rebuilt with 1-piece components instead of the two piece and the disc brakes were upgraded to the "big brake" kit. The axles have 3.54 gears, so not the 4.09/4.10, I must have mixed that up with the Gladiator axles I was also looking at.
    The swap seems pretty straightforward and should be relatively bolt-on according to some folks at Jeepster Commando Club.
    My question is around the lift since I'm going to go ahead and take care of that when I do the swap. I want to go with a 4" lift so I can widen the track a bit to give the Jeepster a little more of a JK type look that my son wants, so I need to clear the fenders with 31" tires. However, I'm having a hell of a time finding a lift for the Jeepster. The ones I can find, seem very expensive for what they are. Where the Jeepster has a 2" leaf up front and 2.5" spring in rear just like the CJ7 and on top of that I'm swapping to CJ7 axles, can I just use a CJ7 lift? That would also take care of the u-bolts for swapping to the Dana 30 and a few other odds and ends I'd need to get otherwise. There's much more selection and price ranges that run the full range from cheap to expensive. Leaf springs are not my forte and I'm sure there's more that goes into the equation than just the width, but from my reading it seems like between the Jeepster and the CJ everything else is basically the same. Before I buy a CJ7 lift and screw up, I just wanted to double check my plan here. Y'all have been very helpful so far. IF that will work, it seems like at that point all I'd need to do is bolt in the axles and lift and then swap out the front yolk on the Dana 20 to a 1310 and get a new front driveshaft rather than those plus a laundry list of small odds and ends.
     
  12. Apr 18, 2020
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Hi Jon - I have not heard it done before... I would guess that the front eye to the pin rear leaf lengths are different, preventing a direct swap. If so, possible the outboard mounts on the Jeepster could be moved. IIRC the Jeepster also used a very large diameter loop and bolt for the bushings on the rear, which may rule-out a verbatim swap. Is the Jeepster front 2" width? I had thought they were 1.75".
     
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  13. Apr 18, 2020
    JonAllenTX

    JonAllenTX New Member

    Round Rock TX
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    Thanks Tim - mine is 2" in the front. My understanding is they switched to 2" when they switched to Saginaw steering.
     
  14. Apr 28, 2020
    Sierra Bum

    Sierra Bum Member

    The High Sierra
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    I don’t know the Jeepsters super well but I think I remember seeing that the rear springs are asymmetrical—-the axle is not centered on the spring. But to confirm, take some measurements of your suspension from the spring hangers & shackle bracket holes. And measure the spring length and the spring ends to center pin/ axles. This will give you an idea what may fit. CJ7 springs are symmetric (axle centered) and around 44” long both front and rear. 2” wide front, 2.5” wide rear.
     
  15. May 1, 2020
    fhoehle

    fhoehle Sponsor

    Harford Township, PA
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    Jeepsters from my recollection have a very long rear spring setup. CJ rear springs do not fit. One option is to have packs made for the rear and buy CJ packs for the front, or change spring hangers to match the CJ springs. It would be a shame to get rid of the long Commando leafs though.
     
  16. May 1, 2020
    fhoehle

    fhoehle Sponsor

    Harford Township, PA
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    I just looked and Alcan has made springs specifically for Jeep Commandos before. I would give them a call to check out price and lead time, as they are custom made springs.
     

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