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T90 To T18 Swap

Discussion in 'Early CJ5 and CJ6 Tech' started by colojeepguy, Aug 5, 2022.

  1. Aug 5, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    For those who haven't been following the Colorado epic thread, I'm having clutch and/or trans issues with my CJ. This is a 70 with a stock 225 and cable operated clutch setup, with a T90J & D18 with a Warn overdrive.
    Basically, I can start the engine, depress the clutch, and I can shift into any gear without a problem. So, I put it in 1st, drive away, and when I try to shift most of the time I can't get it out of 1st gear! When I can shift out of 1st, it won't shift into 2nd. There's no grinding or anything, it's just like 2nd isn't there. Same with 3rd. I don't think this is a clutch problem because I can shift while at a standstill no problem. I can also shift the overdrive while in motion with no issues. But I've never seen a transmission act this way.
    Any ideas?
     
  2. Aug 5, 2022
    jeep2003

    jeep2003 Well-Known Member

    Upstate NY
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    I would say a problem with the shift forks or maybe the synchros are ate up. Have you done anything with it or even had a look inside? If the clutch operates as it should I think you can rule that out. what about reverse? 1st and reverse are on one fork and 2nd and 3rd on the other
     
    Ol Fogie likes this.
  3. Aug 5, 2022
    Rich M.

    Rich M. Shoe salesman 2023 Sponsor 2022 Sponsor

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    Synchronizers, dogs or shift tower.
     
  4. Aug 5, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Seems to me if it was a synchro problem it wouldn't matter if it was moving or sitting still. Shouldn't it have a T14? Not that it matters of course in this situation.
     
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  5. Aug 5, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    I assume the oil level is good?
     
  6. Aug 5, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    Originally, yes.
    Oil level is good.
     
  7. Aug 5, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    I don't "think" it's a synchro issue...1st gear in a T90 is non synchro.
     
  8. Aug 5, 2022
    iharding

    iharding Quitter

    Tacoma, WA
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    Binding input shaft bushing?
     
  9. Aug 5, 2022
    Twin2

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    I forget who it was . and it had to do with a T14
    front bearing retainer had come loose
     
  10. Aug 5, 2022
    supertrooper

    supertrooper Member

    moreno valley, ca
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    I would remove the transmission cover and take the shift tower off and inspect the internals for anything wrong. Also it could be a roll pin the holds the shift forks to the rails could have backed out and might preventing the forks from shifting properly
     
    Last edited: Aug 5, 2022
    dozerjim likes this.
  11. Aug 5, 2022
    Jw60

    Jw60 It's not flat, it's aired down. 2022 Sponsor 2021 Sponsor

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    Can you start out in 2nd or 3rd?
    Sounds like a synchro assembly issue if it is fine at a stop.

    The Trouble-18 would definitely fix the issue.
     
  12. Aug 5, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Have you tried shifting from 1st to 2nd at low speed? Just get it rolling in 1st and try shifting to second? I think it's clutch related myself like cable stretching maybe? How is the clutch adjustment/pedal free play?
     
    dozerjim, jpflat2a and colojeepguy like this.
  13. Aug 6, 2022
    kenb

    kenb Cleverly disguised as a responsible adult

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    The way I'm reading it you say you sometimes can't get out of first to neutral. I don't think it's a clutch issue. You can push a transmission out of gear even without depressing the clutch. I would think your issue lies in the shift tower or some issue on the main shaft that gives too much freeplay.
     
    colojeepguy likes this.
  14. Aug 6, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    That scares me....I don't want to kill my overdrive!
     
  15. Aug 6, 2022
    jeep2003

    jeep2003 Well-Known Member

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    you can probably check the nose cone tightness through the access hole just have to get the clutch fork loose and out of the way. But thats probably not the problem because it would leak alot I would think
     
  16. Aug 6, 2022
    47v6

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    Fix the T-90 with a T-18!

    Some info that may be of relevance or not..
    I one time put a T90-j input into a T90 that had a T-90c cluster... Well it didn't work in the sense that it would not shift into 2nd or 3rd. First was fine, clutch worked like yours.. So, You have something that has let loose in your transmission. Pull the shift tower and take a look in there. Also, dont be afraid of tearing into a T-90. They are easy to work on, light and you can get all the help fixing or repairing one here. I did my first rebuild in my back yard in Arizona 25 years ago with just basic hand tools.
     
  17. Aug 6, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    I rebuilt this one, about 20 years ago, and it's been working fine till now. I wasnt doing anything abusive when the problem started, we'd stopped for gas in Buena Vista, and when I pulled out of the gas station, I couldn't get it to shift.
     
  18. Aug 6, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    20220806_084055.jpg

    I pulled the top. Everything looks good, but I can't move the 2-3 synchro at all.I think I should be able to move it by hand even if I have to move the shafts around a little bit, but I can't get it to budge at all. I'm not sure how that relates to the 1st gear problem, as the 1st reverse gear slides easily.
     
  19. Aug 6, 2022
    homersdog

    homersdog Tulsa, Ok 2023 Sponsor 2022 Sponsor 2021 Sponsor

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    How do the shift rails in the cover look?
     
  20. Aug 6, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    Good
    20220806_085232.jpg
     
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