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tranny trouble shifting...HELP

Discussion in 'The Garage' started by myrenhouston, Feb 2, 2004.

  1. myrenhouston

    myrenhouston Registered Member

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    well i have an 87 k5 350/350. my tranny seems to have given out. im pretty sure every gear still works it just revs real high in each gear. i can get it too shift by manually using the column shifter. this is when i start driving in low and shift through each gear. but when i start in drive i dont get much of a reaction. could it be the throttle valve cable???
     
  2. duece21

    duece21 1/2 ton status

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    There is alot more people on here that know more than me, but reading alot of the previous posts check cable adj and valve. Hopefully some of these guys will chime in. /forums/images/graemlins/thumb.gif
     
  3. Fubeca

    Fubeca 1/2 ton status

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    When this happened to me it was a cracked Low Reverse Cam. It can crack if your wheels are still spinning one direction and you give it gas in the other direction (stuck in the snow or mud). Anyway, I had to rebuild mine.
     
  4. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    ON your Th-350 tranny there is no throttle valve cable like there is on a 700r4. The cable you are reffering to is the kickdown cable on the th350. If you disconnect it the tranny won't downshift when you floor the pedal... In a 700r4 it will cause line pressure to go to max, and if not adjusted properly will burn up the tranny quick.
    If the tranny is shifting very late and hard, and usually only by shifting it manually. It would be in the vacuum modulator which is the engine load signal for a 350 or 400 tranny. you need to check the vaccum line from the manifold going down to the vacuum modulator on the back of the transmission... Unplug it at the tranny and make sure you are getting a good vacuum source, the line isn't kinked or broken.. the next thing to check would be the vacuum modulator to make sure it holds vacuum or just replace it since it is about $7 bucks.
    I ended up putting a hose clamp on the vacuum line that goes to the modulator because it kept falling off and not wanting to shift. Only other thing i might think of is the engine condition, if it is running like crap and has a vacuum leak, there could be another issue going on here.

    Good luck. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
     
  5. 4xcrazy

    4xcrazy 3/4 ton status

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    I had a similar problem with the TH350 in my car, /forums/images/graemlins/frown.gif found out it was the hard vacuum line going to the shift solenoid on the pass side of the tranny, it had rubbed a small hole in it from rubbing up against the firewall, wasn't getting full vacuum reading off the engine. Fixed it and shifted fine ever since. /forums/images/graemlins/doah.gif Check it out, just my .02 cents
     
  6. 99firehawk

    99firehawk 1/2 ton status

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    [ QUOTE ]
    ON your Th-350 tranny there is no throttle valve cable like there is on a 700r4. The cable you are reffering to is the kickdown cable on the th350. If you disconnect it the tranny won't downshift when you floor the pedal... In a 700r4 it will cause line pressure to go to max, and if not adjusted properly will burn up the tranny quick.
    If the tranny is shifting very late and hard, and usually only by shifting it manually. It would be in the vacuum modulator which is the engine load signal for a 350 or 400 tranny. you need to check the vaccum line from the manifold going down to the vacuum modulator on the back of the transmission... Unplug it at the tranny and make sure you are getting a good vacuum source, the line isn't kinked or broken.. the next thing to check would be the vacuum modulator to make sure it holds vacuum or just replace it since it is about $7 bucks.
    I ended up putting a hose clamp on the vacuum line that goes to the modulator because it kept falling off and not wanting to shift. Only other thing i might think of is the engine condition, if it is running like crap and has a vacuum leak, there could be another issue going on here.

    Good luck. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif

    [/ QUOTE ]




    I 2nd that /forums/images/graemlins/thumb.gif
     

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