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th350 lagging on 2-3 shift

Discussion in 'The Garage' started by ducttape114, Oct 21, 2003.

  1. ducttape114

    ducttape114 1/2 ton status

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    before i thought it was just slipping real bad between shifts, so i replaced the tranny and its still doing it /forums/images/graemlins/confused.gif. is there something i need to adjust somewhere?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Lagging how? Like it won't upshift?

    Could it be that your detent cable isn't adjusted correctly, and is too tight all the time?
     
  3. ducttape114

    ducttape114 1/2 ton status

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    not upshifting smoothly. the 1-2 is nice and firm. then the 2-3 shift: starts the shift then the truck stops accelerating and the RPMs climb a bit, then i can feel the shift, then its still not accelerating, then the RPMs drop and i accelerate again. all this happens over about 3 or 4 seconds. detent cable is the one on the pass side correct? i dont have one now, i did before with the other tranny. so i dont think that is the problame.
     
  4. R72K5

    R72K5 Banned

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    definitely slipping 2-3

    cable is the one on pass side of tranny case, yep, black plastic housing alot like an accelerator cable or bicycle brake cable in appearance
     
  5. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Did you have that tranny rebuilt, are you using the same valve body? This is a totally different transmission you put in?
    Sounds like its probably time for a shift kit. Go get a $40 B&M stage 1 or 2 and spend the hour putting it in. /forums/images/graemlins/thumb.gif A shift kit raises the line pressure, and will decrease slippage between shifts like you're describing.
    Warning: stage 2 will chirp the tires. /forums/images/graemlins/grin.gif
     
  6. ducttape114

    ducttape114 1/2 ton status

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    im not real wise about trannys so please excuse my lame ass lingo.

    the tranny was used from another member on the site, he said it shifted fine when he pulled it and i trust him.

    the valve body is the vacume deal on the back next to the output right? if so then i am using the old one.

    this is a totally different tranny i put in

    i really dont think it is slippage because ive had two different trannys and they both "slip" exactly the same. i am thinking its maybe a linkage or a vacume problame maybe? but like i said im not real good with trannys. thanks guys
     
  7. Beast388

    Beast388 1/2 ton status

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    [ QUOTE ]
    the valve body is the vacume deal on the back next to the output right? if so then i am using the old one.


    [/ QUOTE ]

    No, that is the vacuum modulator. Since you are using the same one as before, and have the same symptom as before, it would be wise to change it. You should be able to get a new one for less than $15. /forums/images/graemlins/thumb.gif

    You should also check to be sure there isn't a kink in the line and that there are no vacuum leaks. /forums/images/graemlins/thumb.gif
     
  8. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    CHeck your vacuum line going to the modulator, if there are cracks or a hole or something your tranny will do weird stuff.
     
  9. ducttape114

    ducttape114 1/2 ton status

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    ok cool thanks guys. next problame is, what vehicle came with a th350 and a diesel? i belive all the diesels came with 700r4s. i guess i can try to find a part #. thanks again guys.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Maybe the late 70's early 80's 5.7 Olds diesel trucks? If that doesn't work, diesel cars in that same time frame MAY have had TH350's, although they could have been TH200's.
     

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