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Identify Dana 25 Vs 27?

Discussion in 'Early CJ-5 and CJ-6 Tech' started by Jim Eyster, Apr 5, 2017.

  1. Apr 5, 2017
    Jim Eyster

    Jim Eyster New Member

    Central Ohio
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    If I take a look at my front axle, how do I tell if it's a Dana 25 or 27? Visually, whats the difference?
     
  2. Apr 5, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    If it's a 25 the number will be cast into the top of the differential housing. That's the most definite way I can think of at the moment.
     
  3. Apr 6, 2017
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    No number on the 27?
     
  4. Apr 6, 2017
    garage gnome

    garage gnome Rust polisher Sponsor

    Western MA
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    I thought the breather location helps to tell them apart? I know Dana 25s are on the cover and I'm pretty sure a Dana 27 has it on the top of the cast housing.
     
  5. Apr 6, 2017
    AtomicYJ

    AtomicYJ Sponsor Sponsor

    Richmond Hill, GA
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    My 27 has the breather on the housing and it also has a 27 cast into it
     
  6. Apr 6, 2017
    75 DJ

    75 DJ Member Sponsor

    Des Moines, IA
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    Mine has a 27 cast into it as well
     
  7. Apr 6, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. Sponsor 2019 Sponsor

    cordele, Ga.
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    so does mine.
     
  8. Apr 6, 2017
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

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    x2
     
  9. Apr 6, 2017
    Keys5a

    Keys5a Sponsor Sponsor

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    The Jeep you have pictured appears to be pre-'64 due to the lid on the top of the cowl, so if your front axle is original, it should be a D25.
    -Donny
     
  10. Apr 6, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    I wasn't sure if it was cast like the 25 is.
     
  11. Apr 6, 2017
    Jim Eyster

    Jim Eyster New Member

    Central Ohio
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    Yep, that was a '53 M38A1. I don't have that one anymore. But the CJ5 I have now has the breather on the cover, so probably a 25. I'll look for a number on the housing.
     
  12. Apr 7, 2017
    Snouts out

    Snouts out Member

    Covedale OH
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    What's the difference in the internal components? There has to be some differences ,other than the housing!
     
  13. Apr 7, 2017
    garage gnome

    garage gnome Rust polisher Sponsor

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  14. Apr 7, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    The only differences are:
    The ring and pinion (D-27 has smaller diameter ring)
    The differential case itself
    The differential case bearings and shims
    The pinion inner bearing. (the cone and cup) plus the pinion depth shims
    Outer pinion bearing and seal and preload shims are same as D25
    The housing and the cover are different.

    Also the wheel spindle bearings (D27 is slightly wider/ larger)
    The D27 hubs and hub seals (same as drum brake D30 hubs and seals)
     
  15. Apr 7, 2017
    duffer

    duffer Rodent Power Sponsor 2019 Sponsor

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    In my experience, the ring and pinions in either the D25 or D27 are generally adequate for a somewhat stock Jeep and maybe tires up to 33's. That can not be said for corresponding spider gears and axle shafts which seemingly sometimes disintegrate without much cause. But looking at a D25 ring gear more suggests a go-cart component than one for a Jeep------
     
  16. Apr 7, 2017
    Warloch

    Warloch Did you say Flattie??? Staff Member Sponsor

    Falcon, CO
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    Ya - 33" tires and rocks forced me to the D30 up front. Now I don't shell the front axle, just blow a U-Joint and since that is easy to fix on the trail, a brake point I'll keep over the other options.
     
  17. Apr 7, 2017
    Keys5a

    Keys5a Sponsor Sponsor

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    I think the 33" tires are beyond the capabilities of a Dana 25 unless it is used very gently. I have a Willys Wagon down in the yard with an exploded 25. Its got a pile of teeth shucked off in the bottom of the housing, and this was running 31" tires when that happened.
    -Donny
     
  18. Apr 9, 2017
    Snouts out

    Snouts out Member

    Covedale OH
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    What year did the Dana 27 come into production,for the CJ5?
     
  19. Apr 9, 2017
    Focker

    Focker I Hate Being Bi-Polar, It's Awesome. Staff Member Sponsor 2019 Sponsor

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    Jim Eyster likes this.
  20. Apr 9, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    The model 27 came into production for a very short time in 1961.
    That was the model 27 and it only came with 5.38 gears.

    I re- emerge in late 1962 (early 63 model year) as the 27 AF and was then standard with 4.27 gears and 5.38 optional.
     
    Jim Eyster likes this.

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