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Technical 904 transmission

Discussion in 'The Hokey Ass Message Board' started by 46poncho, Jan 13, 2019.

  1. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

    Hi all, I am trying to install a 904 transmission behind a 318 small block for my 1950 Plymouth. Are all 904 Transmissions the same, I have a 1989 904 and a 1969 904, I wanted to use the 1989 transmission so I change the front seal and filter but I cannot seem to get the torque converter sank all the way down in the 89 transmission. The torque converter will however go all the way on the 69 transmission. I'm not sure what is going on whether I have the wrong seal or the torque converters are different from 69 to 89 or the transmission is different from 69 to 89. Any help would be appreciated thanks.

    Sent from my SM-S327VL using The H.A.M.B. mobile app
     
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  2. 1930 A
    Joined: Apr 8, 2006
    Posts: 125

    1930 A
    Member

    I think if you look at the imput shafts of the two transmissions you'll find they are different.
     
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  3. daliant
    Joined: Nov 25, 2009
    Posts: 637

    daliant
    Member

    The '89 transmission will most likely use a lock up converter, the '69 uses a regular non lock up converter, so you can't mix and match them.
     
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  4. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    lock up started around 1977, not all of them had it at first, but by 89 they probably did.

    also beware the converters for different engines are balanced differently, for example the 360 requires a good sized weight on it, while the 318 (at least the older ones I"ve worked on) don't.
     
    Last edited: Jan 13, 2019
    brad2v, fauj, 46poncho and 1 other person like this.
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  5. It's the input splines....18 verses 21 I think.....ask me how I know....the transmission shop screwed up my converter by not paying attention when I took it in for a rebuild
     
    46poncho likes this.
  6. And what Jim said on 360 motors......
     
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  7. JOECOOL
    Joined: Jan 13, 2004
    Posts: 2,704

    JOECOOL
    Member

    The later one is most likely a 998 , when they started using high rear end ratios they put a lower low gear in and a lockup convertor.If that it the case will have an extra feed for the lock-up .
     
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  8. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    the lockup has a little smooth area at the end of the input shaft splines, about half an inch long. Pretty easy to spot.

    904.jpg
     
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  9. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

    So I think everyone is correct it is a lock up trans, I have been trying to decode the numbers, only thing I have figured out it is somewhere between 1981-85. Correct??? 20190114_174304.jpeg 20190114_174814.jpeg

    Sent from my SM-S327VL using The H.A.M.B. mobile app
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    yeah, but one of those stamped number tells you the build date, you could probably find how to decode it and get it more specific, if it matters.

    I forgot which one it is, and I'm too lazy to look it up. The part number is 1981-85, as you said.
     
  11. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

    It is 8475 bit not real sure how to decode it

    Sent from my SM-S327VL using The H.A.M.B. mobile app
     
  12. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    according to the fancy internet date decoding page, it's

    Day 8475 is Wednesday, October 10, 1984
     
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  13. patsurf
    Joined: Jan 18, 2018
    Posts: 151

    patsurf

    you didn't stay lazy very long.....
     
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  14. VOETOM
    Joined: Aug 6, 2006
    Posts: 233

    VOETOM
    Member
    from MO

    From Car Tech's new book on Rebuilding 727 and 904 transmissions, it is a 1981-85 truck version. 4058398 318 A-999 Wide Ratio-LU

    also in a 1982 -1985 car. 4058398 318 A-999 LU-
     
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  15. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

    I found that fancy page!!! Thank you for the help

    Sent from my SM-S327VL using The H.A.M.B. mobile app
     
  16. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    the list I downloaded a while ago shows a lot of applications.

    trans.jpg
     
  17. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

  18. VOETOM
    Joined: Aug 6, 2006
    Posts: 233

    VOETOM
    Member
    from MO

    Great, our data matches! The good thing is it is a wide ratio lockup which will be good for some mileage and off the line performance.
     
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  19. 46poncho
    Joined: May 24, 2009
    Posts: 139

    46poncho
    Member
    from Indiana

    ok, so I got a torque converter from my friend that gave me the trans, it is the proper converter, as I was carrying it to the car I shook it and heard something inside move, there is no fluid in it. is that normal??? I would hate to put it all together and find out it is bad and drop the tranny again??? again, thanks for your knowledge!!!
     
  20. squirrel
    Joined: Sep 23, 2004
    Posts: 41,083

    squirrel
    Member

    Yeah, that is normal.

    Sent from my Trimline
     
    46poncho likes this.

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