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700r4 lockup switch?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Jonny-K5, Jul 18, 2004.

  1. Jonny-K5

    Jonny-K5 1/2 ton status

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    i've heard of using a manual lockup switch for the TC on a 700. what does it accualy do? disable lockup? lockup in any gear?

    the new tranny i got from bowtie overdrive locks up as soon as it hits 4th gear. i always thought they are supposed to only lock up with light throttle, and unlock as you step on the gas, before it downshifts into third. my old tranny's lockup with burned out.

    anyhow, its a pig once its hits overdrive.its great for high speed freeway driving, but otherwise sucks. so what the deal with this switch?
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    anyhow, its a pig once its hits overdrive.its great for high speed freeway driving, but otherwise sucks. so what the deal with this switch?

    [/ QUOTE ] /forums/images/graemlins/screwy.gifThats what it's for. It's for plugging along at highway speeds. OD shouldn't be used any other time. A manual switch enables you to lock the converter in any gear.
     
  3. Blue85

    Blue85 Troll Premium Member

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    700s were setup differently for different years. I don't know what year valve body BT overdrives is using, so I don't know if yours has a hydraulic lockup valve or not. The TBI trucks did not, so the lockup was controlled entirely by electrical signal. The earlier ones used electrial and hydraulic signals. With one of those, the high TV pressure from accelerating will also unlock the TCC.

    Regardless, you can always overide lockup just by cutting power to the solenoid. Easisest way is to tap into the wires going to the brake switch. It is a N/C switch, not to be confused with the N/O switch that powers the brakelights.
     
  4. Jonny-K5

    Jonny-K5 1/2 ton status

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    [ QUOTE ]
    /forums/images/graemlins/screwy.gifThats what it's for. It's for plugging along at highway speeds.

    [/ QUOTE ]

    ya duh, but say im accelerating up to speed merging onto the freeway, each gear shift is like 6-800 drop in rpm, motor stays in its powerband, then hits overdrive. it would do another 6-800 drop, but the thing locks up immediatly, so the rpms drop over 1000. then the motors gotta chug til it gets back into its powerband. once your up to speed its great but getting there sucks.

    i'd like to be able to keep it from locking up til im ready, and be able to unlock to pass someone without having to put the pedal to the floor to make it shift into third.

    it would also be nice to lock it up when i want to keep it in third, for mountain driving for instance, so the thing isnt constantly slipping creating heat.

    [ QUOTE ]
    Regardless, you can always overide lockup just by cutting power to the solenoid. Easisest way is to tap into the wires going to the brake switch. It is a N/C switch, not to be confused with the N/O switch that powers the brakelights

    [/ QUOTE ]

    i've thought about doing this but i'd like to be able to manually lock it in other gears as well.is there a kit or a way to hook up a switch to do both?
     
  5. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Just wind it up a little more in 3rd then drop it in 4th. /forums/images/graemlins/dunno.gif
     
  6. Thunder

    Thunder 3/4 ton status

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    Sounds like the wireing to the tranny isn't hooked up right, The solonoid is not getting power to it, or the TV cable isn't adjusted right.
    The TC should not stay locked all the time.
    Check your wireing.
     
  7. TorkDSR

    TorkDSR 1/2 ton status

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    just run the grounding wires through a floor mounted hi-beam switch and now your left foot has something to do /forums/images/graemlins/thumb.gif
     
  8. Blue85

    Blue85 Troll Premium Member

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    If you can give it tons of throttle and it stays locked in OD, then you are definately locking just on a 4th pressure switch. I think the best setup for this is the factory one. It uses a vacuum switch under that hood that prevents lockup with low vacuum (acceleration), among other things.

    Always being locked in 4th is not so bad. It's better safe than sorry. You want to be turning some rpms to be unlocked so that you have good oil flow for cooling. Under most driving conditions, the factory setup keeps you locked in 4th gear.

    It sounds to me like your axle gear ratio is too high or the TV cable isn't adjusted right. A 700 is unhappy under either of those conditions. /forums/images/graemlins/1zhelp.gif Make sure the TV cable is right. What gears and tire size do you run? If you want to run with gears too high for your tire size, at least swap out the governor weights to prevent premature shifting. In fact, you probably want to take the weights off altogether or run a Camaro governor. Not a long term fix, but could keep your tranny alive a little longer.
     
  9. TorkDSR

    TorkDSR 1/2 ton status

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    so the camaro governer id weight less...?

    and that gives you higher shift points cause it has to spin faster?
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    IIRC it's actually heavier weights would delay shifts, thus causing them to occur at a higher shaft RPM.

    The governor is spun off of the output shaft, and is a valve that has weights atached to it...when the weights swing out, the valve moves.

    Someone makes a 700R4 governor weight kit, I saw it in a Corvette magazine at one time. Probably B&M or the like.
     
  11. Jonny-K5

    Jonny-K5 1/2 ton status

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    [ QUOTE ]
    Just wind it up a little more in 3rd then drop it in 4th.

    [/ QUOTE ]

    thats what i've been doing but its kind of a lame fix. i think if i spend all the time and money getting a new tranny in it should act the way i want it.

    [ QUOTE ]
    Sounds like the wireing to the tranny isn't hooked up right, The solonoid is not getting power to it, or the TV cable isn't adjusted right.
    The TC should not stay locked all the time.
    Check your wireing.

    [/ QUOTE ]

    i asked the tech guy at bowtie when i went thru the pressure checking and driving test for warranty. he said it is not supposed to unlock in 4th. the wiring is the unmolested stock plug.

    tires are 33's and gears are 4.56
    im sure the TV valve is set up right too. the guy said the results from the pressure test were great.

    i just did some research at the bowtie website. im going to get the manual lock up switch so i can lock it up in 2nd or 3rd. then i'll wire up another switch to disable lockup. good thing i like switches /forums/images/graemlins/grin.gif
     
  12. Jonny-K5

    Jonny-K5 1/2 ton status

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    [ QUOTE ]
    It is a N/C switch, not to be confused with the N/O switch that powers the brakelights.

    [/ QUOTE ]

    whats n/c and n/o mean?
     
  13. TorkDSR

    TorkDSR 1/2 ton status

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    normally closed normally open...

    and to the best of my knowledge it is NOT supposed to always be locked in 4th
     
  14. Blue85

    Blue85 Troll Premium Member

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    Heavier weights lower the shift rpm. The governor valve moves based on the balance of the springs and the weights. The weights are pulled out by centrifugal force as the governor spins. The heavier the weight, the more the force acts on it and pulls it out sooner.

    I run a Camaro governor and it is basically the same as my stock truck one except that there are no weights. That is, the structure of the little wings that move out is the total weight, there is no extra added. I started out grinding material off my weights, but I couldn't even tell the difference in shifting. Then I found the Camaro and one went: /forums/images/graemlins/eek.gif. So just for grins I threw it in. As it turns out I really liked it, so I never went back to add weight. I don't know what the WOT 1-2 shift point is, though. It's above 5000rpm /forums/images/graemlins/yikes.gif.
     

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