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TH350. . . .where's the third gear!?

Discussion in 'The Garage' started by BowtieRed, Jun 15, 2003.

  1. BowtieRed

    BowtieRed 1/2 ton status Author

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    TH350. . . .where\'s the third gear!?

    well i figured i better post this now. . . my tranny needs a little persuasion to shift into second sometimes and by that i mean moving the shifter to neutral and back to drive (not allowing time to shift to neutral) and then it will shift, but i can't get to 3rd gear- which means if i don't want to blow my engine up i have to stay below 60, well i don't HAVE to go on highways as i don't make any long trips, but i'd like to be able to for the future. anybody else had this problem? i know it's there because when i let off the gas at high speed it won't rev the engine (from the wheels turning you know. . . )

    also- i don't know if this is my driveshaft or what, but after about 20-30 minutes of driving i can feel a vibration in my foot and it gets worse and worse for a little bit then stays the same, but doesn't come back after i let the truck sit. what could this be? it doesn't vibrate when coasting
    thanks,
    red
     
  2. Silver84k5

    Silver84k5 1/2 ton status

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    Re: TH350. . . .where\'s the third gear!?

    when things go wrong inside the tranny generally they need rebuilt.

    There is a valve i belive it is on the passenger side of the tranny, You can adjust the way the tranny shifts by screwing this valve in or out, Do a little bit at a time, until it works how you want it, IF you cant get it to start shifting, then you might as well start looking for a place to rebuild it, I got a basic rebuild for $350, then the price can go up as you start adding Better parts inside the trans.
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: TH350. . . .where\'s the third gear!?

    I don't know if this will cure your problem or not but it is cheap enough to do anyway, replace the modulator valve. It is located on the passenger side rear of the transmission and has a vacuum line attached to it. Actually, before chaging it make sure the vacuum line hasn't fell off of it or the manifold.
     
  4. bigblock44k5

    bigblock44k5 1/2 ton status

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    Re: TH350. . . .where\'s the third gear!?

    i would take it to a tranny shop. they have free diagnosing, and chances are that it wont need a total rebuild. my be some stupid little made in china part.
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    Were you pounding on it just before it started doing this?

    That is the symptoms of a blown sprag. Your not is second or third your somewhere in between. The sprage keeps the forward drive drum form spinning backwards. If it spins backwards you don't get 3rd.
    Drop the pan. If you find chunks of metal and rollers that the remains of the sprag. When it goes it takes out the forward drive drum. /forums/images/graemlins/crazy.gif
     
  6. BowtieRed

    BowtieRed 1/2 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    as long as i've owned it it never went into thrid- although it could have been the time my brakes went out and had to use park as a brake- would that do it?

    if that's the case, can it be fixed?
     
  7. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Re: TH350. . . .where\'s the third gear!?

    Check the vacuum line running to the tranny. A lot of times its something small, but maybe it needs a rebuild.
     
  8. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    Yeah it can be fixed as long as the case isn't damaged. My 75 had the same symptoms when I bought it. After talking to a trannjy guy what gets a sprag blown is shifting from Reverse to Drive while on the gas if your rocking it to get unstuck.

    If it's the sprag you looking at a rebuild PLUS some hard parts like the Forward drive drum . I built mine myself. Parts for the rebuild were $150. Local tranny shop sold me a used drum, sprag and pump assembly (unrelated to sprag failure) for $75. My TH350 actually has a TH250 foward drive drum with the TH350 Piston in it so I could get the normal amount of clutches in it for a TH350 and it has a TH350c pump asembly. I built it 4 years ago and still doing fine.
     
  9. BowtieRed

    BowtieRed 1/2 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    maybe i should just buy a remanned TH400 from autozone with a 1 year warranty and runn it as hard as i want and if it doewn't blow, then hey, it's a keeper /forums/images/graemlins/grin.gif
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    [ QUOTE ]
    maybe i should just buy a remanned TH400 from autozone with a 1 year warranty and runn it as hard as i want and if it doewn't blow, then hey, it's a keeper /forums/images/graemlins/grin.gif

    [/ QUOTE ]
    Well you would also need a transfer case and drive shafts. TH400 is longer then a TH350 and the TH350 is 27 spline and a Th 400 is 32.
     
  11. BowtieRed

    BowtieRed 1/2 ton status Author

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    Re: TH350. . . .where\'s the third gear!?

    aren't there adapters? or i could just get a combo of off pirate
     

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