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tork converter lockup

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TorkDSR, May 27, 2003.

  1. TorkDSR

    TorkDSR 1/2 ton status

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    i have a 700 outta an 86... if i wire the tork converter correctly, and get it to lock up manually, will it stall the engine if i apply it in park?

    i have it wired up and i cant seem to get it to lock up, any thoughts would be nice.

    Thanks
    Ryan
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes it would stall the engine in park, but I'm not sure that you *can* apply them while in park. Pretty sure the internal pressure switches in the tranny prevent that from happening.

    Only time I've ever seen them lock up while not moving, or coming to a stop, was when the TCC solenoid itself has failed.
     
  3. TorkDSR

    TorkDSR 1/2 ton status

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    what i meant to say was; in gear at a stop, if i apply the lockup would the truck stall?

    is it a clutch setup, or teeth that grab? how do they lock up?
    Ryan
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    It's actally like a clutch disk, nd if you were successful in applying it at a stop, yes, the engine wil die.

    It's controlled by the TCC solenoid, which either allows fluid to move through it, or blocks the fluid path. Can't recall much more than that on how it operates, but it is fluid/pressure operated.
     
  5. the professor

    the professor 1/2 ton status

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    An 1986 TC lock-up is controled souly by the TC lock-up solenoid..NO other vavles...It wasn't until after October of 1987 that the Aux Valve Body was added to control the Torq Converter
    --
    Aplying the TC clutch in neutral or park will have no effect.. but aplying the TC clutch in any other gear, will be just like having a manual trans with the clutch out.
    --
    It is NOT recommended to run the TC clutch engaged when the trans shifts... The torque-converter acts like a "cushion", to absorbe the energy of the shifts.. with the converter locked-up, all that energy is taken by the clutches and the band, leading to early failure.. not to mention the wear on the gear train an hard parts..

    /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  6. MousePowrd

    MousePowrd 1/2 ton status

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    I have a manual switch on my Grand National for racing, and it will not stall in Park with the TCC switch on. Fluid is not sent to the TCC until 2nd gear or something, I am far from a tranny expert. But with the switch on, it will REALLY lug the motor on the 1st-2nd shift, and you will know if its working.

    As stated above driving with the TCC locked will burn out the clutch bands. I only use mine at the track.
     
  7. Aux valve body huh... So, is there any electrical tap point @ xny or CPU to get a signal that would let you know "idiot light" that your TC was in lock up...like for diagnosis???
     
  8. Sorry, original post said "wire" LOL...I'll check for some schematics. I think mine is engaging...whenever.
     
  9. jmd

    jmd Registered Member

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    [ QUOTE ]
    Yes it would stall the engine in park, but I'm not sure that you *can* apply them while in park. Pretty sure the internal pressure switches in the tranny prevent that from happening.

    [/ QUOTE ]

    I believe this is true.

    http://www.thirdgen.org/newdesign/tech/torqueswitch.shtml

    "Connecting pins A & F locks the convertor in any gear except low."


    [ QUOTE ]
    An 1986 TC lock-up is controled souly by the TC lock-up solenoid..NO other vavles...It wasn't until after October of 1987 that the Aux Valve Body was added to control the Torq Converter
    Aplying the TC clutch in neutral or park will have no effect.. but aplying the TC clutch in any other gear, will be just like having a manual trans with the clutch out.


    [/ QUOTE ]

    I am surprised an 87-down 700 wouldn't have a 4th gear pressure switch and use it.

    I guess I could go lockup the one in my car but um, it's a 1991 trans.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    TCC explanation

    nice and indepth.

    Don't know as I believe the "locked while shifting is bad" argument. Friend has a 700 with hydraulic only TCC lockup (no TCC solenoid operation) and has been running it for years (hard) that way. Professional tranny guy did the install if that means anything.

    In any case, the lockup when shifting argument has been around for quite some time, and it's a pretty polarized argument. If the tranny is built strong, it probably doesn't matter. Most tranny "issues" (soft, sliding shifts) are caused by GM, because soccer mom complains when she feels the transmission shift gears.
     
  11. Blue85

    Blue85 Troll Premium Member

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    OK, it's time for me to come in and clear some things up.

    First, yes, you can wire an idiot light to tell you when it is locked. I know this because I have one. However, there are actually two places to monitor, the lockup pressure switch in the tranny and the lockup solenoid signal. Both must be active for the TCC to be locked. One is a pull high and the other is a pull low, so I think you could wire a light between them. I have one LED for each. Two lights means locked.

    Next, the torque converter on a pre-87 will not lock up all the time power is applied to the connector. Like I alluded to above, there are two things controlling lockup. First, the lockup control valve in the valve body has to supply pressure. Second, the solenoid has to be engaged, or that pressure is vented to the pan.

    The hydraulic signal is based on the gear you are in, TV pressure and the 4-3 downshift valve. So whenever you open the throttle up, you are shifting in or out of overdrive or you are in 1st gear, the TCC will not be locked.

    The electrical signal is based on a vacuum switch and a brake switch (in series). The vacuum switch is ported vacuum, meaning that you will never lock the converter at idle. The vacuum switch closes only under cruising conditions and not the low vacuum of heavy throttle. You also never get lockup when the brake pedal is engaged.

    If you want to look at these signals, you can tap into the tranny connector or splice in underhood. The vacuum switch is mounted on the firewall near the brake booster. The TCC pressure switch drives an electrically operated vacuum switch for the control of the EGR valve, so you can tap into that signal there. The switch is normally on the passenger side valve cover near the firewall.

    The third wire going to the tranny is generally +12V switched only by the brake switch.
     
  12. TorkDSR

    TorkDSR 1/2 ton status

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    every one seems to have conflicting arguments on the pre/post 87 stuff.

    let me clear up that the tork converter operation on this trans is fully manual. it consists of a high beam switch on the floor.


    i sure know how to kill a post /forums/images/graemlins/crazy.gif
    the plug on the top of the trans is set up for three wires, do i need to energize two of then with one ground?
     

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