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Dana 27a With Loose Pinion Or Wrong Pinion

Discussion in 'Early CJ5 and CJ6 Tech' started by HugeHugh, Oct 13, 2019.

  1. Oct 13, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    I have a 79 CJ5 with a Dana 27A front axle from about 1967. This axle has broken ring gear teeth and a wobbly pinion gear. I disassembled the axle and I found a ring gear and pinion from 1967 and 'Y' stamps on the bearing caps and housing surface telling me it's been worked on at least once before. The wobbly pinion shaft is because the yoke is not long enough to press the outer pinion bearing to the bearing cup. My guess is the person who cobbled this jeep together to sell as a roller grabbed the first fine spline yoke they could find that would fit the drive shaft. Here are some pics that show the broken teeth, the diff cover mating surface, the yoke and the pinion. Is it possible the carrier and the pinion are from a different but similar axle? Does anyone have a picture of a correct 1967 Dana 27A yoke that I can compare to the one I have? Does anyone see a discrepancy in these parts?

    Is the pinion number 31389 and is the ring gear number 31390 correct for a Dana 27A?
     

    Attached Files:

  2. Oct 13, 2019
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I’m not super competent in this area..... but I’m pretty sure there is supposed to be a crush sleeve in there that retains tension on the bearings. I may be wrong. Others will chime in.....

    After a quick google search, the d27 doesn’t use a crush sleeve for pre load.
     
  3. Oct 13, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    A '79 CJ did not come with a 27 front axle. Instead, it used a Dana 30. The 27 is anachronistic, being a closed knuckle design. If this Jeep is really a '79, I'd suggest you put it back to an open knuckle 30 axle. If it's really a '59 or a '69, a replacement 27 should be pretty easy to obtain, since they are often replaced by a 30 as a significant upgrade. Not worth repairing IMO.
     
    Last edited: Oct 13, 2019
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  4. Oct 13, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    I just found this post from 2016. Dana 27 Front Driveshaft Discussion... It has a photo of a Dana 27 yoke next to a Dana 30/AMC20 yoke. The Dana 30/AMC20 yoke is what I have on my front Dana 27. It looks like the correct Dana 27 yoke has the additional metal to reach the thrust washer and secure the outer bearing. I don't know if the Dana 27 axle was good before someone put the wrong yoke on it or if the axle was already damaged. Doesn't really matter now I guess.
     
  5. Oct 13, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    Thanks for the feedback timgr. I agree that a Dana 30 is what should be under the front of this CJ5. What should be in the rear of a 79? I have a Dana 27 in the rear as well. At least I think it is. The rear axle brake setup is exactly like the front and the diff cover is the same. I assumed it is a Dana 27, but I haven't cleaned it off or opened the cover to verify. I will search prices on a Dana 30 front and whatever should be in the back end.
     
  6. Oct 13, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    I cleaned the axle shafts and found an interesting twist to the story. The right (short) axle shaft spline that enters the differential has an interesting shape. The right axle shaft is in the foreground and the left axle shaft is in the back ground. To twist the splines in this direction, the driver was in reverse.
     

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  7. Oct 13, 2019
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    From what I'm read over the years these axles fail when in reverse due to the load shifting towards the front axle, like a good launch forward will pull a wheelie on the rear axle but innreverse a dana 27 is much weaker than a dana 44 going forward.
     
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  8. Oct 13, 2019
    HugeHugh

    HugeHugh New Member

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    Good point. I'm learning a lot as I dig through YouTube videos, forums and books like "Differentials: Identification, Restoration & Repair". I will post some pics of the axle housing tomorrow. I don't want to rebuild it and I don't want anyone else getting it if the axle is unsafe. I've read that the guys that work on some of the older iron like CJ2s an CJ3s can use parts from a D27, so if my D27 is truly bad, then I'll put the good pieces on Ebay at a fair price.
     
  9. Oct 13, 2019
    nickmil

    nickmil In mothballs.

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    Parts from a 27’that work with a 25 are pinion (spider) and side gears, axle shafts (an upgrade) spindles, and brakes/hubs/locking hubs. Knuckles can be used as well and some have stronger castings in the steering arms than a 25.
    The 27 uses a vent in the carrier (pumpkin) and 25 has the vent in the cover. maybe I missed it but post a pic of the rear and someone here can id it. The only 27 rears I can think of are Scout 80’s. Early Jeepster Commando’s used a taper axle 30 which may be what you have. WW2 MB’s and GPW’s used a 23-2 which was full float and shared many parts with the 25 front.
     
  10. Oct 14, 2019
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Yes they are, 3.73 ratio.
     
  11. Oct 14, 2019
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    I'd source the correct axle assemblies for your Jeep.
    Much better than what you have now.
    And the cost would not be prohibitive.
     
  12. Oct 14, 2019
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Given that mess and as Tim suggested, just go find a complete, usable D30. It will be WAY cheaper than working with the existing axle.
     
  13. Oct 14, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    AMC 20, the Corporate axle. 3.54 ratio standard, 3.07 or 4.10 optional. There is a '79 TSM here that will tell you about the axles and the Jeep generally. Jeep® Parts Manuals online

    A '79 frame only fits the 20 unless you move the spring pads on the older axle. If the 20 is still there, I would compare ratios front to rear. That could explain existing breakage. Ratios must match, front to rear.
     
    Last edited: Oct 14, 2019
  14. Oct 14, 2019
    Keys5a

    Keys5a Sponsor

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    A Dana 20 rear has a round rear cover vs a Dana 44 rear has "flat/parallel" sides on the cover. I believe a '79 should have the Dana 20 rear, and is supposed the have an open-knuckle Dana 30 front axle.
    -Donny
     
  15. Oct 14, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I'm sure you mean AMC 20 Donny, not Dana 20. The Dana 20 is a transfer case, made by Dana-Spicer Corp, which a 1979 Jeep CJ-5 would also be equipped with. The AMC 20 can be called the M20 or the Corporate axle, since it was built by AM Corp and was also used in their passenger cars. And it does indeed have a big hemisphere of a cover, like a basketball.

    upload_2019-10-14_17-21-12.png
     
    Last edited: Oct 14, 2019
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  16. Oct 14, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    I appreciate the confirmation. It's a shame the ring gear is so damaged and the pinion is nicked up as well.
     
  17. Oct 14, 2019
    HugeHugh

    HugeHugh New Member

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    I will be searching for new axles very soon. Here are some pics of the rear axle that is in this Jeep. As I said earlier, the brake components are exact matches to those on the front Dana 27A. I will clean this rear axle this evening and find more numbers. You guys will probably id it right away.
     

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  18. Oct 14, 2019
    HugeHugh

    HugeHugh New Member

    Austin County Texas
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    Are these welds typical of a Dana 27A that has not been repaired at the knuckles? It is rare that knuckles would be welded back to the axle tubes, but it can be done. My 76 Scout II had a Dana axle in the front and the only way to change the caster is to grind off the knuckle welds, reorient the knuckle and weld it back. I know that is a different style of knuckle than the Dana 27 closed knuckle. This is my first Dana 27, so I don't have any reference to what the factory tube to axle connection looked like.
     

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  19. Oct 14, 2019
    HugeHugh

    HugeHugh New Member

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    This is an incredibly useful link to have. Thank you.
     
  20. Oct 14, 2019
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Well, it's a flanged Dana 44, keeper.
    Can't quite read the tag number though 992X30 ?
     
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