th400 rebuild

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500, 472, 425, 368 Discussion, th400 rebuild in Cadillac Engine Discussion; Hey guys, long time no post. I'm planning on rebuilding the 472 in my 72 hearse next spring. I figured ...
  1. #1
    72HearseGuy is offline Cadillac Owners Member
    Automobile(s): 1972 fleetwood hearse
    Join Date
    May 2012

    th400 rebuild

    Hey guys, long time no post. I'm planning on rebuilding the 472 in my 72 hearse next spring. I figured id service the transmission too. Its not too bad, sometimes it shifts a little hard. No major issues though. What kind of kit should I buy, and what video/manual do you suggest. Any tips? Trying to get everything ready so I'm ready come rebuild time.

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  3. #2
    Roadmaster75's Avatar
    Roadmaster75 is offline Cadillac Owners Member
    Automobile(s): 1978 Eldorado Biarritz
    Join Date
    Feb 2012

    Re: th400 rebuild

    hard shifting could be one of two items that only require external serving/troubleshooting:

    Governor set up and adjustment (see shop manual)
    simple vacuum modulator adjustment or replacement (cheap)
    Also, ensure the vacuum line to the modulator is getting full vacuum from the manifold.
    This means inspect the little rubber hose and connections to ensure there are no leaks.
    With these items checked and a fresh filter/fluid change I'm guessing you
    have a perfectly good trans without a teardown.
    my 2 cents

  4. #3
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
    Automobile(s): '80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
    Join Date
    Feb 2005
    Southern NJ

    Re: th400 rebuild

    Hard shifting can be a good thing. A poor vacuum signal should be ruled out first as mentioned. If it were mine I'd change the pump seal while the engine is out. Maybe the driveshaft seal too if it leaks, change filter and fluid and enjoy. The engine rebuild is enough stuff at one time.

    Maybe find another transmission and rebuild it in your spare time.

  5. #4
    BRUCE ROE is offline Cadillac Owners Fanatic
    Automobile(s): Eldorado
    Join Date
    Jun 2009

    Re: th400 rebuild

    If your trans is original, it is way overdue for a new set of soft parts (rubber seals). A blown piston seal
    could BURN UP a perfectly good trans. Good news, it only costs $30. I'd take it apart & check damage before
    deciding. A set of clutches will double the price, except yours (like my 70) likely has an extra plate in the
    direct clutch, which I've never seen in a kit yet. Full kit has steels double the price again, I NEVER replace
    steels or other hard parts, if they show no wear. Esp DON'T replace the 3 wavy plates with flat, if you
    want it to shift like new. Get a new set of torringtons, I replace plastic thrust washers with metal.

    There are a few tools that greatly help the rebuild; I learned from the factory service manual. Converted
    my 70 to a switch pitch, so smooth. Bruce Roe

  6. #5
    GM_Parts_Guy is offline Cadillac Owners Member
    Join Date
    May 2013
    If your dead set on doing a rebuild (i look at it like your right there with the motor rebuild would not be much extra to do the trans and you know you have a fresh trans mated to the fresh motor) Trans-star and TCI Trans both make very good kits. I've used both.

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