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D18 T/c Cotter Pin

Discussion in 'Early CJ5 and CJ6 Tech' started by Fresbone, Sep 3, 2022.

  1. Sep 3, 2022
    Fresbone

    Fresbone Member 2023 Sponsor 2022 Sponsor

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    7071C61A-78D1-4856-9CA1-E86F3FBFF39A.jpeg I am taking off my D18 T/C and there is no cotter pin holding the SM420 shaft in place like it said in the service manual. Is that because it is attached to an SM420 instead of a standard jeep tranny? Do I need to add one when I reinstall the T/C?

    On a related yet dumber note, I obviously drained the oil from the T/C before I got to this point, but I didn’t pay attention to which plugs went where. There is a large square bolt and a smaller square bolt, both of which look like they have the same thread. Which one goes in the fill hole and which in the drain hole?
    Thanks.
     
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  2. Sep 3, 2022
    duffer

    duffer Rodent Power

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    Does the mainshaft have a cotter pin hole? If not, you should be using the self locking nut on there. I think the plugs are just 1/2" NPT threads. I use a hex drive plug in the bottom.
     
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  3. Sep 3, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

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    duffer beat me to it...check to see if there is a cotter pin hole on the mainshaft. The sm465 adapted shaft I used from novak did NOT have a cotter pin, but required a locking nut. Drain plugs are interchangeable as far as I know.
     
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  4. Sep 3, 2022
    Jw60

    Jw60 Airbender and interrupter of the light guard. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    Cotter pin isn't used on a lot of aftermarket stuff. My replacement t-90 mainshaft doesn't have it, overdrive can't use it anyway.
     
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  5. Sep 3, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    Correct, I have an aftermarket T90 I got in a parts deal and the main shaft on that transmission does not have a hole for the cotter pin, so I used a self locking nut (Nylock?). I don't trust those self locking nuts for this, so I also used some thread locker on it.
     
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  6. Sep 4, 2022
    Fresbone

    Fresbone Member 2023 Sponsor 2022 Sponsor

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    Related: why no crush washers on T/C or transmission? Not needed or simply missing?
     
  7. Sep 4, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    Crush washers where??
     
  8. Sep 4, 2022
    Jw60

    Jw60 Airbender and interrupter of the light guard. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    Your not setting a bearing preload like a pinion.
    Pinion has tapered bearings, transmission has ball bearings and roller bearings so no need for anything special you just need to keep it from backing off the mainshaft.
     
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  9. Sep 4, 2022
    Fresbone

    Fresbone Member 2023 Sponsor 2022 Sponsor

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    Sorry. Crush washers in the T/C and tranny drain plugs like there is on the oil pan drain plug.
     
  10. Sep 4, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    Nope, the holes for those plugs go straight into the case, if you put a washer there it will end up sloshing around in the oil until it gets picked up by a gear. They are pipe thread plugs and once tightened should not leak but if it concerns you it wouldn't hurt to dab a little sealant on the threads.
     
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  11. Sep 9, 2022
    duffer

    duffer Rodent Power

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    I would not use a nylock style lock nut. jpet stripped one of those right off the mainshaft.

    "This weekend was another 2 days of what I would call abusive wheeling. Lots of horsepower in Midwest muddy creeks and ditches. I decided that if I am going to gun it hard, I would not use low range but to go to granny low in high range. Less stress on the spur gears and puts all the load on the X98 super gears. At one point I tried to jerk an SXS out of a ditch backwards with my kinetic rope and I ended up in permanent neutral .... turns out that the torque was so great that the force of the helix on the gears stripped the locking nut right off:

    [​IMG]

    To be fair, this is a nylock that I have used more than once. I had a stock nut but the force also messed up some threads on the end of the main shaft.

    [​IMG]"

    From this thread: https://www.thecj2apage.com/forums/lower-transfer-case-gears_topic47516_page23.html

    Use a flex top stock style all steel nut.
     
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  12. Sep 10, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    Screenshot_20220613-063129_Chrome.jpg
     
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  13. Sep 10, 2022
    duffer

    duffer Rodent Power

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    My guess is that did not loosen up on its own but like Jeff indicated, the force of helix on the gears just stripped it. Again, I think it is the style of lock nut and perhaps grade also (doesn't look like grade 8). A four thread engagement is just insufficient. I wouldn't be surprised if the stock castled cotter key nuts are twice as strong, not to mention there is no way for them to loosen up. I don't think my current AA mainshaft is drilled for a cotter key but it absolutely will be when Jeff's 5.07:1 gear set goes in.
     
  14. Sep 11, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    The threads stripping on the shaft is kinda concerning.
     
  15. Sep 12, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    Yeah, I am not happy about it, but it is what I got. The main shaft in this transmission isn't drilled for a cotter pin and I will just wait and see if it holds. This Jeep isn't going to see any hard trail use.
     
  16. Sep 12, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

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    The sm465 Novak adapted mainshaft to work with the D18 is the same way - no cotter pin hole. I think I prefer the metal lock nut (like used for a pinon) as compared to a nylock....
     
  17. Sep 13, 2022
    duffer

    duffer Rodent Power

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    Absolutely! Part of the problem with a Nylock is the temperature. I would guess that could be 150 degrees, if not warmer, and the holding ability of that nylon insert diminished to a large degree. If one has the transfercase removed, it shouldn't be too difficult to drill the main shaft. Carbide tipped bit and use a stock castle nut for a guide, locked into position with another nut.
     
  18. Sep 13, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    The transfer case is attached to the transmission but both units are still on the bench. I hate to take it apart but think it may be worth the effort to do that and drill the shaft for a cotter pin, else I will be worried about it coming loose every time I take the Jeep out in the woods.
     
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  19. Sep 13, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    FWIW-
    This is the stock setup on my T18.
    Nylock nut , no cotter pin hole in the trans shaft.
    20220913_193704.jpg
     
  20. Sep 14, 2022
    Jw60

    Jw60 Airbender and interrupter of the light guard. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    I'm not sure how a d20 is held together but it seems like the cotter pin went away on the ford D20, I don't know on jeep but there is the opportunity for the cotterpin to interfere with the D20 output shaft and a D18 Pto.
     
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