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700R4 Slipping?

Discussion in 'The Garage' started by KrebsATM02, Dec 9, 2003.

  1. KrebsATM02

    KrebsATM02 1/2 ton status

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    I tried searching, but I'm getting some weird error.

    Anyways, my brother's 700R4 is doing some weird stuff at hi way speeds. When we are going fast enough to be in OD if you let off and then get back on the pedal the rpm's go up for a couple seconds until the tranny "catches" it and then everything is find until you let off. It doesn't try to switch gears or anything like that.

    History: I drove it in highschool and powerbraked the poor thing alot. It's been abused and has about 135,000 on it. This has only started happening recently.

    TIA - Doug
     
  2. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    /forums/images/graemlins/thinking.gifsounds like its time for a rebuild. the overdrive is usually what goes first.
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Check the fluid, not enough fluid will cause it to slip just like that.
     
  4. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    :homer: doh! im an idiot

    yea check the fluid first /forums/images/graemlins/thumb.gif
     
  5. k5guyva

    k5guyva 1/2 ton status

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    It seems to me that the torque converter could be unlocking. Have you checked for holes in your vacuum lines?
     
  6. KrebsATM02

    KrebsATM02 1/2 ton status

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    Fluid is at the correct level. This weekend we are going to do the filter and change the fluid.

    The TC lockup is controlled by the computer on a 700R4 isn't it? At least for this year? 87 TBI
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]

    The TC lockup is controlled by the computer on a 700R4 isn't it? At least for this year? 87 TBI

    [/ QUOTE ]
    Yep, even the CCC setups like mine are controlled by the ECM.
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]

    The TC lockup is controlled by the computer on a 700R4 isn't it? At least for this year? 87 TBI

    [/ QUOTE ]
    Yep, even the CCC setups like mine are controlled by the ECM.
     
  9. 88Silverado

    88Silverado 1/2 ton status

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    [ QUOTE ]
    It seems to me that the torque converter could be unlocking

    [/ QUOTE ]

    It could be. If you let off the gas and it starts to slow down then re-apply your foot on the gas it can (and probably will) unlock the converter thinking your accelerating. Thats probably whats happening. The computer doesnt override the TC lockup. The position of the TV cable and trans pressures internal will override the lockup. All the computer does is apply 12V to the trans telling it to lock the converter. Even if the converter is locked and your traveling at 60MPH, you put your foot on the gas the converter will normally unlock (depending on load) but not downshift out of OD.

    Check the fluid, make sure its not brown or smells burnt. If it does, rebuild time. Also check to make sure the TV cable is adjusted correctly. Sounds to me the converter is unlocking like its suppose to.
     

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