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TH350 shift problems

Discussion in 'The Garage' started by blazer k5, Oct 28, 2005.

  1. blazer k5

    blazer k5 Newbie

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    I have a 75 blazer with a Th350 tranny and when driving it shifts from 1st to 3rd it will not shift in to 2nd gear. Is there any hope for the tranny or do I have to rebuild it.
    I am not sore but it seems like it shifts in to 2nd some times when shifting down from 3rd

    O.G
    Norway
     
  2. 1-ton

    1-ton 1/2 ton status Premium Member

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    How many shifts are you feeling? You should only feel two...1st to 2nd and 2nd to 3rd. You are not going to feel three shifts because it is already in first. I am not even sure if it is possible for a transmission valve body to skip from 1st to 3rd. I think a valve body must use the 2nd gear valve body ports to get to the 3rd gear valve body ports. But I am not positive of this. At least this reply might get the ball rolling for other people to reply.
     
  3. blazer k5

    blazer k5 Newbie

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    I am only feeling one shift and the rpm tells me that It shifts from 1st to 3rd and its also need a weary high rpm to shift. If the rpm is too low it will shift up and down for some times depending on how much throttle I give.

    O.G
    Norway
     
  4. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    Bummer,
    I would start by making sure all tranny fluid lines are open, not blocked. Take them off at radiator or cooler and off at tranny and blow them out.

    Check vacuum modulator vacuum hose for leaks or blockage do same as above with it, take off at vacuum port and modulator.

    Since it doesn't cost much if the tranny hasn't been messed with in a while just replace the vacuum modulator and do a fluid and filter change and see what happens. If this doesn't fix the problem then yep rebuild time. or maybe torque converter??
     
  5. blazer k5

    blazer k5 Newbie

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    Thanks for your answers
    I can also ad that if I put it in 2nd whit the gear shifter it will not go in to 2nd gear it stars in 1st and stays there.
    I will try your answers tomorrow

    O.G
    Norway
     
  6. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Sorry dude. It sounds like your intermediate roller clutch is not locking so it is effectivly shifting but not doing any good when it does. rebuild time :(
     
  7. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    Yep time to tear into it :(

    And just a few minor modifications ;)
     
  8. blazer k5

    blazer k5 Newbie

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    I was afraid for that :( . I also spoke whit one that works whit American cars earlier this day and he said the almost the same, his gees was that roller was cracked and let the oil true so the pressure disappear.


    Yes I will do some modifications that’s for sure :waytogo:

    Thanks for yours help :bow:

    O.G
    Norway
     

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