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TH350 Hard shift questions

Discussion in 'The Garage' started by laketex, Jun 12, 2002.

  1. laketex

    laketex 3/4 ton status

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    Ok, I got my tranny rebuilt about 2 years ago, but didn't get it installed till feb of this year. I've run it about 30 miles and it shifts like crap. The only way it'll shift up is with my foot flat on the floor and the motor wound way out, then it does with a huge jerk. Downshifting is sporadic, sometimes it does right, sometimes it has to be done manually. Need to know what to do here. Fluid's fine, tranny's out of warranty. Do i need a new rebuild or is it something simple?
     
  2. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Sounds to me like your vacuum modulator isn't getting any vacuum. Is it hooked up? A friend of mine didn't have the metal line to run the vacuum to the modulator so he just ran hose all the way down. The hose colapsed and his transmission was acting the same way.

    Mike
     
  3. Sandman

    Sandman 3/4 ton status Author

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    Yeah check the vacuum line. It'll cause those things to happen.
     
  4. MudbogAD

    MudbogAD 1/2 ton status

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    I would assume the vacuum line or modulator.
     
  5. Sandman

    Sandman 3/4 ton status Author

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    Yes, Sorry for the vagueness. I meant the vacuum line that connects from somewhere on the intake manifold that goes down to the back of the transmission to the vacuum modulator.
     
  6. Brady

    Brady 1/2 ton status

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    I think it is the Vacuum mod. or line is off.Had this happen on the wifes Sub.
     
  7. laketex

    laketex 3/4 ton status

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    Thanks to all of yall. It was indeed the vaccum line. All split out and not doing its job properly. I have a metal hard line and a little bit of hose at each end to connect the two. The hose was messed up so I replaced each with a piece of fuel line. works and shifts great now. Thanks again to all of yall. Saved me a TON of work.

    Bryan
     

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