700-R4 Issue

Discussion in 'Transmission & Driveline Topics' started by CorkyE, Sep 23, 2020.

  1. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    700-R4, TCI constant pressure valve body, TCI vacuum kit for lockup converter, BTE 10" 3K lockup converter. Mainly street driven, problem popped up again, getting worse. It's going to around 4K rpm before it will shift out of 1st. When it does, it skips over 2nd, goes to 3rd. I also noticed the other day the torque converter was dropping in/out of lockup at light throttle, not what it's been doing. I don't know if that's related or a different issue. Just dropped the pan, changed fluid and filter with no change. While the pan was down, I bypassed the 4th gear pressure switch, put vacuum on the lockup switch, and solenoid does work.

    I had similar issue before. Called TCI tech and was told to pour in a bottle of Lube Guard, jack the back wheels up and run the transmission through the gears. I did that and the problem went away for a while, but it's back. I did use Lube Guard when I put the new fluid and filter in.

    This is a constant pressure valve body. TCI tech told me to adjust the TV cable to where the piston is all the way back when the throttle is wide open.
    Thanks.
     
  2. ssupercoolss

    ssupercoolss Veteran Member

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    When i threw a stock 2004r at my Monte Carlo, the shifting was like you described. Really late 1st gear shift, under pretty much any throttle. I dont know this for absolute certain, but i am fairly sure the plunger that the tv cable operates was stuck mostly open. Really odd pressure readings. After i had worked the tv cable back and forth in anger, i dropped the pan, and checked plunger/cable operation,(which was now normal) set the tv just pushing the plunger in slightly at an idle, and never had to touch it again. You do have alot more going on there than i would know about though, but i did have an Impala SS with a 4l60E, which would shuttle in/out of lock up like yours, and that was the converter going south.
     
  3. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    First time, TCI guy told me he thought the plunger/piston was sticking, that's why he recommended Lube Guard. When I had the pan off this time, I had my son mash the gas pedal while I watched. The TV cable needed a slight adjustment but the piston moved freely. As for the TC lockup going in/out, I think that's a separate issue. Aggravating, there's very few miles on either.
     
  4. camaro71/holland

    camaro71/holland Veteran Member

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    Sounds like you have a problem with the 2nd gear band or servo.
    Because you say you have no 2nd gear at all, I don't think the band is shot, but more of a mechanical problem like a blown/damaged seal on the servo or broken pin anchor on the band.

    Start with the easy check and pull the servo. Work from there.
     
  5. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    I do have 2nd, it's skipping over it if I leave it in 4th. I can manually shift through all gears, but it's still a very high shift point. I should have clarified that earlier.
     
  6. camaro71/holland

    camaro71/holland Veteran Member

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    Same band applies in 4th as in 2nd, so if 3-4 is ok, that would rule out the band.

    If the timing of other shifts is ok, that kinda rules out the governor, unless one of the weights/springs is acting up. Since it's an easy check, I would inspect the governor.

    Then move on to the servo piston and check the seal on the 2nd gear apply piston.

    Then if still no joy, pull the VB and inspect the 1-2 valve train.

    If still no happy ending, things might get more complicated.....
     
  7. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    I pulled the governor, the piston was stuck inside, wouldn't move with the weights. Pulled it apart and cleaned, hopefully this is the issue.

    Edit - ugh, that may have been an issue, but it wasn't the problem. Looks like I'll be pulling the transmission.
     
    Last edited: Sep 28, 2020

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