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Any TH400 techs out there?

Discussion in 'The Garage' started by jim b, Aug 1, 2003.

  1. jim b

    jim b Registered Member

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    I'm having trouble with an early TH400 (Buick Nailhead version with AMC adapter ring) It won't take off in first gear unless I manually shift it down (then it sounds like a standard trans, but has no trouble pulling a 5 ton load) Then at highway speed, even the slightest throttle pressure makes it downshift to second (I have to back off the gas to get it to upshift) Vacuum modulator is hooked up, and passing gear unplugged. Any ideas guys? carnuck@hotmail.com
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    it could either be a sticky valve in the valve body or a bad modulator
     
  3. BowtieRed

    BowtieRed 1/2 ton status Author

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    i had the same problem with it downshifting in second, my guess, judging from my trans pan is that the clutches are so burnt that the pressure requires a downshift- and it made me think that even more because it was worse when hot. now the clutches are so bad i don't have 2nd gear.
     
  4. bigbadchev84

    bigbadchev84 1/2 ton status

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    im having this same prob, did you ever figure it out?
     

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