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T90A vs T90C, What a difference!

Discussion in 'Early CJ5 and CJ6 Tech' started by Brian P, Feb 1, 2009.

  1. Sep 20, 2020
    dozerjim

    dozerjim Member

    western New York
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    Just for curiosity I have a T90F transmission that I think came out of a 2 wheel drive Scout,no transfer just a yoke,are the gear ratios different ?parts useable in a T90A?
     
  2. Sep 20, 2020
    oldtime

    oldtime oldtime

    St. Charles,...
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    IH used various T90’s between 1961 and 1973.
    Most if not all used a 16 tooth main drive gear (input).
    So they are most likely to be suitable with a T90C not the T90A.
    Re-using the IH main drive depends on its length and the IH main shaft will have limited applications.
     
  3. Sep 20, 2020
    Brian Carothers

    Brian Carothers Member

    Reno NV
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    81C20994-1B59-47FD-A176-8716A9A6CA34.jpeg 3DC8313C-C4F9-4073-B3A9-499C273A0AED.jpeg 7B68492A-FEE2-4483-9D1B-7E1C4BDCF959.jpeg
    well there we go I opened up the transmission. What am I working with here? I didn’t spot anything obviously broken.
     
  4. Sep 20, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    T90 guts in a T86 case. Count the teeth on the main drive gear (nearest bellhousing). I expect there to be 18 teeth.
    -Donny
     
  5. Sep 21, 2020
    oldtime

    oldtime oldtime

    St. Charles,...
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    That looks real clean inside.
    Please get rid of the silly putty and put a real gasket on it.
     
    Brian Carothers likes this.
  6. Sep 21, 2020
    dozerjim

    dozerjim Member

    western New York
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    Thanks oldtime,when I get time Ill pull cover off and compare just for giggles
     
  7. Sep 21, 2020
    oldtime

    oldtime oldtime

    St. Charles,...
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    Yeah Jim we’d love to see the inside of your IH T 90.
    Have not found one yet that will convert to a Dauntless bell with T90 C gears.
    Count the input teeth and measure the stickpout.
     
  8. Sep 21, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Not piling on! :coffee:

    Brian, T-90J guts, no doubt. Straight teeth on sliding 1st & R gears, straight splines on the main shaft. The T-86 gear teeth are helical, and the T-86 splines slightly spiral around the shaft.

    It's a good repair for the T-86. You should be happy.
     
    Brian Carothers likes this.
  9. Sep 21, 2020
    Brian Carothers

    Brian Carothers Member

    Reno NV
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    Well I’m glad thats all good. Ill grab a gasket and button it back up. Now i still have the issue of what’s making that rattling noise.
     

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    Last edited: Sep 21, 2020
  10. Sep 21, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The oil in the bottom of the transmission looks milky to me (contaminated with water). If that's all the further it will drain, I'd do my best to suck the rest out. You could add a little mineral spirits or kerosene to the bottom of the case and make the remaining oil easier to remove - just be sure to remove it all, and don't bathe the gears in it.
     
    Brian Carothers likes this.
  11. Sep 21, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Also, the transmission and transfer case share oil, so you should drain both.

    I'd guess it's a Dana 18, but I cant be sure from that angle. If the rear driveshaft is offset to the passenger side, it's an 18.
     
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  12. Sep 21, 2020
    1967 CJ5A

    1967 CJ5A Mike 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Raleigh, NC
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    I bet one of your floor pan bolts is contacting the drivetrain and making that noise. I had that issue with mine, and they can make a loud thunk, especially when the drivetrain shifts from torque. Take a close look at the ends of the bolts to see if they are marked up from making contact, especially the two just above the bellhousing.
     
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  13. Sep 21, 2020
    Brian Carothers

    Brian Carothers Member

    Reno NV
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    I believe so.
    OH ****. So after just reading this, I didn’t drain this at all. The photos above was the level it was at as I opened it.
     
  14. Sep 21, 2020
    Brian Carothers

    Brian Carothers Member

    Reno NV
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    See I thought so too. But the video I have while driving it, I have the floor out with all the bolts out. Still making the noise.

    but now I’m thinking I could have that sound cause there was not enough oil in the transmission
     
    Last edited: Sep 21, 2020
  15. Sep 21, 2020
    hotdogtaco

    hotdogtaco New Member

    Lubbock, TX,...
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    I would love to swap in a T90C with the 5.38s on my M38a1. that combo would have a CRAZY low range crawl speed.
     
    Brian Carothers likes this.
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