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Technical 700R4 Shift Kit Problem

Discussion in 'The Hokey Ass Message Board' started by rockable, Sep 26, 2019.

  1. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
    ALLIANCE MEMBER

    I bought a car that has a 700R4 installed behind a SBC and it has obviously had some kind of "shift kit" installed in it. It upshifts very firmly, which is not really a problem but the downshift is horrible. It is so abrupt that it feels like it's abusive to the drivetrain.

    I have never rebuilt an automatic transmission but am not afraid to learn. I also have never installed a "shift kit".

    What is required to tame and civilize this beast and does it require removal of the tranny? If so, I may wait until winter but this sucks. I've had 3 or 4 cars with 700R4's in them and I know this doesnt have to be this way.

    Thanks for your help.
     
    jetnow1 likes this.
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    I would first very carefully check the TV cable adjustment, and geometry. Might be that transmission itself is fine, but the cable is not set up properly.
     
    270dodge likes this.
  3. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    I did that, Jim. Played with it quite a bit. The geometry is fixed as the SBC has an OT multi port injection system on it.
     
  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    I would get a manual, and some stock parts, and put it back.

    700R4s, especially the early ones, had fairly harsh shifts, resulting in a bunch of customer complaints.

    Adding something to make the shifts harder seems like a really bad idea for a street car.

    Most GM shift kits are a plate, and some check balls. If you're crafty, you can do it, in-car.

    Also, double-check the TV cable.
     

  5. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    A plate is about $30, with the gaskets being about $10. Check balls are $1.20, each, when purchased in a pack of 10.

    Not a ton of scratch to reverse this mod. See if it has a non-stock servo. It might be difficult to spot a Corvette one, unless you can read the part number, but, if you see a big honking billet cap, you'll know it's aftermarket.
     
  6. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    See, I've never installed a shift kit, so I don't know what was done and what needs to be undone.
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Have you had the pan off of a GM transmission?

    Outside:
    [​IMG]
    Business side:
    [​IMG]
    It looks like a brain, because that's what it is.

    That funky iron dookicky behind it is the valve body. It has a bunch of bolts that hold it to the case. Between it, and the case there is a gasket, a plate, and another gasket. That plate has metered orifices (holes) in it that control fluid flow. Above that top gasket, there are a few check balls that control flow direction. Generally, a shift kit has a modified plate, and adds, or removes check balls.

    Here's a typical plate:
    [​IMG]
    Check ball locations (1985, other years vary):
    [​IMG]
     
  8. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    Generally a shift kit is only that plate and the balls. If there are heavy mods, it might have a better servo that controls the band, and some better quality internal components. The internal components, unless full-race, are unlikely to have any effect on feel, even if you change the shifting back to stock. The servo might. That's an easy fix, if you don't like the shifts, after you undo the shift kit.
     
  9. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    Cool! Thanks! That tells me a lot. No problem with taking that off.

    So, I happen to have an old tranny that sat out and got full of H2O because it didn't have a dipstick in it. I used it for mocking up drivetrain in my Buick. Could I just rob the plate and balls (assuming they aren't rusty) off it and use them to put this back to something approaching stock?

    Pretty sure this is an 86 tranny. Any other springs, etc?
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    They made a lot of changes to the 700 every year in the early years...so be extra careful swapping parts from one trans to another.

    you might see if you can download instructions for a few different brands of shift kits, to see what is involved in installing one, then you'll know to do the opposite to remove it
     
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  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    The plate is cadmium plated. The balls are non-metallic. You will need gaskets.

    You should first figure out the age of BOTH of the transmissions. The 700R4 went through a few revisions, one specifically to revise harsh shifting. The parts will need to match.

    Have a look here:
    [​IMG]
    1982-1986 are the first design. 1987-1993 are a different one.

    Please take care that the one from your Buick is not a 20004R

    The spring in the accumulator is sometimes replaced in these kits. I might leave that in there. A old used spring likely won't do you any favors.
     
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  12. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

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    Thanks, guys. That is for sure a 700R4 on the Buick. It has a Trans Dapt adapter to enable the hookup.

    So, any 82-86 parts are interchangeable by 87 on are not. I will double Check both trannys.

    Can I buy gaskets at O'reilly's or some other place?
     
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    Hard parts, yes. The later ones had an auxiliary valve body, which makes many parts not interchange.
     
  14. saltflats
    Joined: Aug 14, 2007
    Posts: 12,592

    saltflats
    Member
    from Missouri

    If i knew what gaskets you needed, I may have some.
     
    rockable likes this.
  15. potshot
    Joined: Jul 15, 2005
    Posts: 70

    potshot
    Member
    from MT

    A high idle speed or sluggish throttle return spring can cause a harsh coasting downshift
    I would hook up a pressure gauge before I started pulling the VB
     
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  16. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    That is not the case here. Thanks.
     
  17. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    Well, crap. I have an 87 tranny in the car and an 85 for parts. Where do I go from here? How would I go about finding "stock parts" or a less aggressive shift kit? Thanks for your help.
     
  18. saltflats
    Joined: Aug 14, 2007
    Posts: 12,592

    saltflats
    Member
    from Missouri

    Check Trans Go.
     
    gimpyshotrods likes this.
  19. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    I'm not interested in installing another kit. I want to "un shift kit" it, I think. This is a cruiser and the mods they did are too harsh for casual driving. I'm worried that the valve body I have has been drilled or something and that I can't get it back to where I want it if I take it apart. It might be best for me to carry it to a pro, who would have parts.
     
  20. southerncad
    Joined: Feb 5, 2008
    Posts: 949

    southerncad
    Member

    Maybe this is too simple of an answer to your question, but can't you contact the person you bought the car from to get some info on the trans build?o_O
     
  21. Long while back, I bought a rebuild kit and "reprogramming" kit from napa that was very very helpful, and it included an instruction set that explained everything to do and why.
    I think it was "Gil Younger" reprogramming kit from TRANSGO.
    It explained every step and explained why.
    The 700R4 I put behind the Stude motor in my pickup around 1993 is still going strong today.
    It still shifts just right in normal use, and can still chirp the tireswhen I hit second really hard when I really get on it, and then it acts civilized again when I'm not getting rough.
    I didn't expect it to keep lasting this long.
    I hope napa still sells those kits. I'm planning another one.

    WHY BE ORDINARY ?
     
  22. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    Maybe. Not sure he knows, since he did none of the work himself. Good point, however.
     
  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    rockable likes this.
  24. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,730

    David Gersic
    Member
    from DeKalb, IL

    You’ll probably need to buy stock parts to replace whatever the “kit” installed or modified. I just did this in the spring, having grown tired of dorking around with a poor shifting 700R4.

    Paid a shop to un-shift-kit it. Kinda goes against my do it myself tendencies, but having no idea what kit had been installed, and what other work and changes had been made by three or four other shops previously, I decided it needed more experience and expertise than I had or wanted to develop.

    Dropped the car off, went on vacation for the week, came back, picked the car up, and now it just works. Wrote a check. Left happy.

    Mine had some kind of kit installed, raising and harshing the shift points. 1-2 was around 20MPH and would almost always chirp the tyres, whether you wanted it to or not. 2-3 was around 55MPH. 3-4 was around 85MPH. The wiring harness for the lockup solenoid had been cut out and removed, though the solenoid was still there. And the TV cable was hooked to an unmodified Holley carb, so the geometry was off.



    Sent from my iPad using The H.A.M.B. mobile app
     
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  25. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
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    Sounds like what I will end up doing. Glad you had a good outcome.
     
  26. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
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    No shame there.

    My capabilities are many, but I often send stuff out to be worked on.

    It saves me some of the little time I have, and puts money in the coffers of businesses I want to see stick around.
     
    rockable likes this.
  27. JeffB2
    Joined: Dec 18, 2006
    Posts: 9,484

    JeffB2
    Member
    from Phoenix,AZ

    You should run a fuel pressure check before you change any thing the guy that did a 700R4 for me ended up doing a slight linkage mod to get it right.
     
  28. rockable
    Joined: Dec 21, 2009
    Posts: 4,428

    rockable
    ALLIANCE MEMBER

    Turns out that the pressure switch that signals "ok" to the TCC was failed closed. So, the torque converter was locking up as soon as the transmission shifted to 2nd, or immediately. A downshift to second with the torque converter locked up is really abrupt.

    Replaced the 12 buck pressure switch and adjusted the TV cable and all is good.
     
  29. 6sally6
    Joined: Feb 16, 2014
    Posts: 2,459

    6sally6
    Member

    Glad it turned out good for you.
    Like many of us..........we assume the worse.
    Always good advice to work from the cheapest-up. Advice I don't think I've ever used!:rolleyes:
    6sally6
     

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