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T90 Lower Surface

Discussion in 'Flat Fender Tech' started by Farmjeep99, Mar 2, 2019.

  1. Mar 2, 2019
    Farmjeep99

    Farmjeep99 New Member

    Illinois
    Joined:
    Jan 8, 2019
    Messages:
    13
    I’m in the middle of a T90 rebuild and I just got the case back from being cleaned and after further inspection the lower surface where the counter shaft is, seems to be scored up. Can this be resurfaced or is the case junk?
     
  2. Mar 2, 2019
    duffer

    duffer Rodent Power

    Bozeman, MT
    Joined:
    Sep 17, 2009
    Messages:
    4,460
    Are we talking about the area of the case below the gear or the thrust surfaces at the ends of the shaft? If it is just the case below the gear and not to the point where the case strength is compromised, a bit of scoring will not have any effect. If the case surfaces at the ends of the counter shaft gear are tore up, probably new case time.

    I have to think the needle bearings on the counter shaft must have been REALLY screwed up to allow the gear to score the case bottom.
     
  3. Mar 3, 2019
    Farmjeep99

    Farmjeep99 New Member

    Illinois
    Joined:
    Jan 8, 2019
    Messages:
    13
    Front lower surface of the case where the thrust washer runs on counter shaft. The face of the case of where the thrust washer rides. It’s scorn. The needle bearings were not pitted and machine only had 28000 miles on it. Didn’t make noise and had oil in it when I changed it to drive it(machine had sat 25+ years). The only reason for tear down was it was leaking and I thought I’d change 73 year old bearing.

    Upon further inspection the 3 shifting pawls one was missing. I’m thinking it ended up on that end and got ground up. That’s why it was the only surface damaged.

    Any thoughts from anyone?
     
  4. Mar 3, 2019
    TIm E

    TIm E Aggressively average

    NW Arkansas
    Joined:
    Mar 2, 2017
    Messages:
    683
    I am not overly familiar with the T90, but usually the trust washers on the cluster gear do not spin against the case itself. There is a tab on the thrust washer that goes into a slot in the case to keep it from turning. The tab/case side of the thrust washer is steel, the side that faces the cluster gear is bronze. The cluster gear spins against the bronze face of the thrust washer, the thrust washer stays stationary.

    If the case surface is still relatively flat and a new thrust washer is used (locked properly with tab in case slot) you will probably be okay.

    **EDIT**

    Jump to the 23:30 mark in the video below. Apparently with the T90, the large thrust washer is as I described above, the small one is opposite, so it may depend on which one is bad...

     
    Last edited: Mar 3, 2019
  5. Mar 3, 2019
    Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Maryland
    Joined:
    Mar 23, 2008
    Messages:
    2,169
    Pics?
     
  6. Mar 3, 2019
    Farmjeep99

    Farmjeep99 New Member

    Illinois
    Joined:
    Jan 8, 2019
    Messages:
    13
    Definitely have some in the morning. It’s 10 degrees outside and the case is in my truck.
     
  7. Mar 3, 2019
    Farmjeep99

    Farmjeep99 New Member

    Illinois
    Joined:
    Jan 8, 2019
    Messages:
    13
    Yes, after looking at this it looks like the larger thrust washer tab broke off at some point and was spinning. The surface is flat and I think it will run just fine. Thanks for for the reply
     
  8. Mar 6, 2019
    EMA

    EMA Member

    Lake Elsinore,...
    Joined:
    Feb 20, 2019
    Messages:
    82
    I am in the middle of a T90 rebuild as well... Came across the same issue.
    Rather than take a chance I replaced the case.
    Just a thought...
    I found another trans...not knowing it was a " IH " trans.... Looks the same...has the same markings ( T90A-1 ) on the case.
    They look the same inside, but trust me when I saw, " THEY ARE NOT "....
    Though the CASE, 1st Gear-Reverse, and the Reverse gear ARE the ONLY parts the same.
    Difference I saw & measured: Main-shaft is a larger diameter....Different 2nd gear ID, Input shaft will need the smaller bearings as the end of the shaft at the Main-shaft is larger, but MUST be matched to the Input-shaft that came with it.
    Just a lot different.
    The IH transmissions are cheaper to buy out there, but beware of this.
    Just saying.... :)

    George
     
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