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tranny shifting problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Aug 7, 2004.

  1. zach78k5

    zach78k5 1/2 ton status

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    I have a 700R4 with a 305, 3.73 and 32in tires. I have played with the TV cable and have it where I want it on the upshifts. My problem is that it doesnt quite seem to downshift when it should. If I adjust the TV cable much further, the truck doesnt want to upshift at all. Is there another adjustment somewhere to help with this problem. Apparently the guy who I bought it from had the tranny rebuilt to handle big horsepower. The main problem is when I round tight corners, second gear leaves me no power but I can only get first gear by shifting on the column. Thanks.
     
  2. unclematty

    unclematty 1/2 ton status

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    I don't know if I could explain it wellenough to make sense of it for ya, my advice, take it to a reputable trans shop, and pay them their SMALL fee for making that quick adjustment, they will need to test drive it to make sure they got it right /forums/images/graemlins/waytogo.gif CAUTION If ya mess up this adjustment, you can burn up your trans very quickly /forums/images/graemlins/deal.gif I know there is a full blown post here somewhere on ck5 about it /forums/images/graemlins/waytogo.gif
     
  3. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Don't PLAY with the tv cable!! There is an excellent link on an old post if you do a search. It's not like the old TH350 where you can mess around with it a bit. Do that on a 700R4 and you're on your way to a rebuild. The TV has to be SET not adjusted. There is just one place for it to be and work right. /forums/images/graemlins/thumb.gif
     
  4. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    [ QUOTE ]
    I don't know if I could explain it wellenough to make sense of it for ya, my advice, take it to a reputable trans shop, and pay them their SMALL fee for making that quick adjustment, they will need to test drive it to make sure they got it right /forums/images/graemlins/waytogo.gif CAUTION If ya mess up this adjustment, you can burn up your trans very quickly /forums/images/graemlins/deal.gif I know there is a full blown post here somewhere on ck5 about it /forums/images/graemlins/waytogo.gif

    [/ QUOTE ]


    ahhhh


    I have a bad feeling we just found my friends problem with 700-r4's /forums/images/graemlins/eek.gif


    /forums/images/graemlins/shocked.gif


    wow /forums/images/graemlins/yikes.gif
     
  5. 75-K5

    75-K5 3/4 ton status

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    [ QUOTE ]
    [ QUOTE ]
    I don't know if I could explain it wellenough to make sense of it for ya, my advice, take it to a reputable trans shop, and pay them their SMALL fee for making that quick adjustment, they will need to test drive it to make sure they got it right /forums/images/graemlins/waytogo.gif CAUTION If ya mess up this adjustment, you can burn up your trans very quickly /forums/images/graemlins/deal.gif I know there is a full blown post here somewhere on ck5 about it /forums/images/graemlins/waytogo.gif

    [/ QUOTE ]


    ahhhh


    I have a bad feeling we just found my friends problem with 700-r4's /forums/images/graemlins/eek.gif


    /forums/images/graemlins/shocked.gif


    wow /forums/images/graemlins/yikes.gif

    [/ QUOTE ]














































    /forums/images/graemlins/doah.gif
     
  6. Blue85

    Blue85 Troll Premium Member

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    In stock form, the 700 does not like to downshift to 1st unless you are very close to stopped. Even at WOT, you have to be going pretty slow, so adjusting the TV cable isn't going to help much. The only real way to change this is to replace the 1-2 shift valvetrain in the valve body. I did this when I rebuilt and it is /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif. Half throttle and above on a corner and she kicks right down. Contact B&M if you want more info. They also have a replacement valve that lets you hold overdrive at high throttle, but I never saw the good of that for a truck.


    You have to set the TV cable according to factory specs. Then if you want firmer shifts, do a shift kit or mod the pressure regulator valve in the pump. If you want higher shift points, change the governor weights, and so on. The point being that the TV cable is NOT a way to adjust shift characteristics. I might move it one click in or out from "correct" adjustment setting, but no more.
     
  7. k-5 jimmy fan

    k-5 jimmy fan Registered Member

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    [ QUOTE ]
    I have a 700R4 with a 305, 3.73 and 32in tires. I have played with the TV cable and have it where I want it on the upshifts. My problem is that it doesnt quite seem to downshift when it should. If I adjust the TV cable much further, the truck doesnt want to upshift at all. Is there another adjustment somewhere to help with this problem. Apparently the guy who I bought it from had the tranny rebuilt to handle big horsepower. The main problem is when I round tight corners, second gear leaves me no power but I can only get first gear by shifting on the column. Thanks.

    [/ QUOTE ]

    Realizing from what you say the tranny may not be stock and could be a special case. I would still highly recommend reading the TV cable section at Bowtie Overdrives. (see link)

    It is the most complete instructions for setting the throttle valve cable for 700 R4 transmission I have found to date and gave me a more complete understanding of the overall system.

    It includes real world photographs with step by step simplified instructions which follows the GM factory manual and can be understood in plain English.

    Bowtie does recommend a pressure test at the pump's diagnostic port be run after the TV cable is set to insure all is well.

    http://www.tvmadeez.com/article/index.php
     
  8. Blue85

    Blue85 Troll Premium Member

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    If you have the TV cable adjusted right (i.e. following the proper procedure, not trying to judge it by feel) and the upshift points are at too low of rpm, then changing the governor weights could help both problems. The transmission would think you are going slower, so it would upshift later and also downshift back to 1st easier. This also helps keep a 700 out of O.D. before it really should be.

    When you say it won't downshift on it's own, what it is the vehicle speed (MPH)? How slow do you have to go for a WOT or near-WOT downshift into 1st?
     

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