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    700R4 shifting problems

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    m1dadio

    Number of posts: 1320
    Location: Victoria B.C.
    Registration date: 2008-10-06

    700R4 shifting problems

    Post by m1dadio on Mon Oct 05, 2009 10:44 am

    Who can help?
    My 1988 700R4 wont shift right. Its a 1988 TPI V8 /700R4 with the original computer and wireing all put into my 65 Van.

    It upshifts way too early including the TCC lock up.

    I adjusted the kick down cable, It now takes longer to make the 1-2 shift but then almost emediatly makes the 2-3 shift and then TCC lock up all too soon.
    The rear gear and tires are different then the donner car but not by much, Do I have to change something to compensate for that? Is the early up shifting a hydraulic control problem?

    I think the VSS works , how accurate I'm not sure. My scanner reads out vehicle speed on a road test and looks generally accurate. (no opperating speedo at this time).


    I also noticed the TCC wil engage while driving no matter what gear I have the shifter in. I know this because my TCC brake switch works so I can touch the brake pedal while driving to make the TCC disengage.

    This trany does not have the vacuum switch, It has the mechanical cable to the throtle valve. I cannot see any evedance of it ever having the vacuum controll either in the donner car or the GM shop mannual.

    It has the TCC solinoid, a brake peddal switch, a high gear switch, the original computer and a Vehicle speed sensor buffer from the donner car.

    I am about to recheck all my wiring installation and would appreciate any comments.

    M1D

    donivan65
    Governor
    Governor

    Number of posts: 8198
    Location: San Diego, California
    Registration date: 2008-05-12

    Re: 700R4 shifting problems

    Post by donivan65 on Mon Oct 05, 2009 11:22 am

    Have you readjusted the cable with the reset button?,,,I guess you could count the threads on the reset button and then vary the position, manually, maybe one thread at a time, in or out and see if the shifting changes,,,,,,,,or maybe the cable is stretched out of limits,,,,,,,,did the trans shift right in the original car? Is the connection of the cable to the throttlebody exactlly the same as before??? VanAgain probably has the instructions for installing a test pressure gauge in one of the side ports that you can use to verify the proper operation of the throttle valve cable,,,,,,,,,

    m1dadio

    Number of posts: 1320
    Location: Victoria B.C.
    Registration date: 2008-10-06

    Re: 700R4 shifting problems

    Post by m1dadio on Tue Oct 06, 2009 8:22 pm

    The cable was exactly as it was from the donner car. I didn't have much chance to road test the donner so I don't know how it was before. I did reajust it like the book says, it changed in that it took longer for the 1-2 shift but then the 2-3 shifty followed by the TCC lock up came way too soon after.

    Joyrde gave this link
    http://www.transmissioncenter.net/700r4.htm

    This is a must read for people with auto trany, and conversions now and being considered. Fantastik imfo for conversions.

    I belive my VSS (speedo) gear is wrong. And the govenor might be sticky from sitting. I also think the "high gear" switch in the trany is done or the wire is shorted to ground. That last one would explane the TCC going into lock up no matter what gear I have the shifter in.

    I'm just using the link above right now to determine what speedo gears I have and need.

    M1D

      Current date/time is Wed Apr 23, 2014 4:47 am