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Axle Swap

Discussion in 'Early CJ5 and CJ6 Tech' started by 56cj6, Nov 1, 2016.

  1. Jan 10, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    Thanks guys.
     
  2. Jan 10, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    I don't have a ratio tag on my rear D44 any other way I can find out. My front axle never had identification on it either, I know it's a 44 but have no idea of ratio. I believe it's been built in 62, has a 225 dropped in on a m38a1 frame.
     
  3. Jan 10, 2017
    tarry99

    tarry99 Member

    Northern California
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    Pull the cover and count the teeth on the ring and Pinion gears.
     
  4. Jan 11, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Most (all?) of these ring gears have the tooth count stamped into the edge of the ring gear. For example, "41 11" is 41/11 = 3.73. You still have to pull the cover ...
     
    commanlerwrangdo likes this.
  5. Jan 11, 2017
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Are you dead set on D20 and the centered rear? Seems to me a good chunk of work for a downgrade in design.

    I swapped in a front 30 along with 11 pack leaves. Spring plates, shocks, ubolts, ujoints, and driveshaft all stock.

    Get it put in and have a drag link cut to length (Herm cut mine) to use the cheap and available regular ball joints.
     
  6. Jan 11, 2017
    commanlerwrangdo

    commanlerwrangdo Member

    Cleveland, Ohio
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    Feb 10, 2014
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    470
    Yep, always there (on factory gears). Have seen unmarked aftermarket ones though...
     
  7. Jan 11, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    Aug 14, 2006
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    Standard ratio 1972 through 1975 was 3.73 with 4.27 as an option.
    Standard ratio after 1975 was 3.54.
     
  8. Jan 12, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    Oct 15, 2015
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    Do you know if you can use d27 knuckles on a d30 axle? I have a disCJ conversion on the 27 already but thought about going with the '73 d30 or a 79' d44 from a scout for my cj5 with a 225 v6. With the 33s and 10.5 wide rims
     
  9. Jan 12, 2017
    Framer Mike P

    Framer Mike P Member

    Hopkinton, NH
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    Jan 4, 2016
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    217
    Your caliper brackets should bolt onto the knuckle with the spindle sharing the six spindle bolts - should be able to unbolt from your d27 knuckle and install onto your d30 knuckle. I believe the scout spindle is 8 bolts so they would not transfer but I would think the scout would allready have disc brakes.
     
  10. Jan 12, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    390
    73 d30 and 44 axle
    I've also got a 44 front from a 79 scout that has 79 cj Dana 30 knuckles already installed on it, but it has 3.07 gears and an open carrier in it. I had on 79 cj.
    The 30 has drums,
    The 44 had disc, I had stock 79 cj parts on it from the knuckle out to the hub, the even worked with the 44 stub shaft

    This is what I could get for my 62 cj5/m38a1 with a 225 v6 and 33X12.5X15 not going off road maybe sand dunes here and there but mainly road worthy. So what would you suggest stay with my 27 with converted disc, or go with d30 and transfer my disc from 27 to the 30, or go with the 44.
     
  11. Jan 12, 2017
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I have been running my 27 for about 21 years, the last 6 or so with 33's. It has 4:88's and a I certainly don't baby it. I have run some some pretty hard core trails and it has held up well. I did a disc brake conversion quite a while back and messed with it for quite a while until I worked all the bugs out but they work awesome now.
    I personally think the 27 gets a bad rap, coming from a guy working on a D30 swap as we speak. :D I may eventually step up to 35's, as a matter of fact I have a line on some now.
     
  12. Jan 12, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    Oct 15, 2015
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    I have an opportunity to get the axle for 100.00 but doing research I think my gears need changing to 4.27 or something like that. Want optimal range. Not off roading but more road Jeep. 4.88 seems high and isn't there a cut off for gears to diff.? Like stock d44 /d27 cut off is 3.73? Would a 4.56 fit in Stock d44, d27?
     
  13. Jan 12, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    And how's your rpms and gas range with the 4.88?
     
  14. Jan 12, 2017
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I got lucky when I bought it, I have a Warn overdrive. I can cruise all day at around 65mph. I love the 4:88's off road with the SM465.
    Someone will know better but I think the ratio break is 3:54 down and 3:73 up.
     
  15. Jan 13, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The breaks are on the Randy's Ring and Pinion site: Common Carrier Breaks I do not endorse or condemn their terminology.

    That is correct for a D30. The D44 breaks at 3.73 and 3.92.

    IME 4.27 is a good ratio that makes Jeeps with tallish tires highway capable. The 4.88 Jeeps I've seen spin pretty fast on the highway, without an overdrive and/or tall tires.
     
  16. Jan 13, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    Yea I was thinking 4.27 gearing with the d44 and d27. If I get these gears can I install them or so I need something else. Beside seals.
     
  17. Jan 14, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    IMHO Running without an O.D. unit I think 4.09 ratio would be best and 4.27 is also doable.
    4.56, 4.88 and 5.38 ratios really need an O.D. or else the RPM gets pretty high for MOST engines.
    A few engines like the old Ford Pinto were designed to operate at a high RPM like 3200.

    If your trying for best gas mileage stay with 3.73 or 3.54 for most engines.
     
  18. Jan 14, 2017
    shaun

    shaun Member

    Lebanon, Ohio
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    Old timr even with larger tires like 33x12.5x15 on 15x10s.
     
  19. Jan 14, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    Your actual tire height is maybe 32" ?
    Ummn Yeah 32" tall tires will be a bit much with 3.54 gears and possibly too fast with 3.73.
    But 4.10 gears should be great with 32" tires and still give pretty good gas mileage too.

    Gas mileage and off road tires are often at odds because wide is bad for MPG yet wide will be good under certain off road conditions. Especially when flotation is required.
    IMHO The best compromise tires for both off road and good mpg will be very tall and very narrow.

    Different engines yield best efficiency at different crankshaft velocities.
    Its all relative to the engine output.
    The stock Dauntless puts out optimum efficiency at 2400 RPM.
    So to get best MPG gear the differentials to run 2400 rpm at your favorite hiway speed.

    According to Speed Calculator your best reasonable hiway mpg and speed will be 61.3 MPH with 3.73 gears @ the stated 2400 RPM.
    MPG may be better with 3.73 but off road speed torque will suffer some .
    There is always a compromise between fuel efficiency and offroad capability.
     
    Last edited: Jan 14, 2017
  20. Jan 14, 2017
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    X2 on Oldimes post. 4.10 with 32s is a good street ratio. 4.27s with 33s work well. If more toward off-road wheeling, 4.88s work well but really start to limit your highway speed vs. gas mileage.
     
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