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Electric to Hydraulic Lock-up Torque Converter

Discussion in 'Projects, mods, restoration' started by 72Gold, Nov 21, 2017.

  1. 72Gold

    72Gold New Member

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    I have just read this informative article which explains almost all I need to know.

    Mechanical override: Lockup torque converters (at https://www.allpar.com/mopar/transmissions/lockup.html )

    So let me start from the beginning. For ease of standardization, I have several Dodge pickups from the 1983 through 1986. We have a few from 1972 as well, but have just about retired those. I recently built a nice 1983 pickup with a Utiline bed for my son. I used the engine and transmission out of a 1987 Ramcharger I had picked up at a bargain. I bought it for the seats, console and glass; have wound up using the entire driveline.

    OK, backing up a little further, I bought my 1985 Ramcharger brand new, ordered it from the dealer. I have over 260,000 miles with amazing reliability. The transmission still shifts the way it did when brand new and the engine remains perfect. I wanted to build a similar reliable pickup for my son as he will off into the world far too soon.

    When connecting the wires on the tranny, I wondered what that one little connector was for? I didn't have a wire to connect to it. It certainly is not present on any of my other pickups and is not shown in the 85 Service Manual. After driving the vehicle for several months, it certainly does not lock up the Torque Converter. After reading several forums and looking at pictures, I now know this connector is to lock up the TC electrically rather than hydraulically.

    Here is my question. I could take the electric brains from the 87 Ramcharger and try to get it to work again to get the TC to lock up. Seems a bit too complex of a solution. Or, I could a connect a 12v lighted rocker switch. Cheap, but manually switching often is not a great solution. I really would like to make it automatic -- hydraulic like my flawless shifting 1985 Ramcharger. What would this take? Would it be just a change of the valve body? Buy a 1985 valve body and install it in the 1987 transmission?

    Thanks.
     
  2. 85lebaront2

    Level 2 Supporter

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    I would think you could as long as the needed hydraulics are in the transmission (correct input shaft, pump and converter) just be sure the valve body you get has the updated control valve and spring (I was working at a dealership when they came out) Trivia note, when we were having problems diagnosing issues, I brought my 1955-56 Packard service manual in and the service manger copied the Twin Ultramatic converter troubleshooting information. The Chrysler zone rep took a copy with him and it appeared about two weeks later, revised to remove the refernces to the rear pump as a TSB.
     
    72Gold likes this.
  3. 72Gold

    72Gold New Member

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    Thanks for the replies. I have heard that their may have been some other changes in the cases from 1985 to 1987, which might make the valve body switch a bad experiment.

    Regardless, I think I have figured out how to use new sensors to make the TC lockup electrically. It is a very simple electric and vacuum circuit.

    I just need (and think I already have these items on the shelf):

    1. Oil pressure switch - normally open - set to close while ascending at 50 psi - connected to the Governor pressure port
    2. Adjustable Vacuum/Electric switch - normally open - set to close while ascending at 7-9 psi, reopen at 3-5 psi
    3. (Optional) Coolant temperature vacuum switch - normally closed - set to open at 80 -100 F
    4. Relay

    All four items will be connected in series. When the vacuum is high, the coolant temperature is above 80 F and the governor pressure is above 50 psi, the TC will lock up. If the oil pressure drops (lower speeds), it will unlock. If the vacuum drops during hard acceleration, it will also unlock.

    Again, thanks to all for the input. I would have spent $250 and a lot of time on a bad experiment. Using the electric circuit, I won't spend hardly any money, very little time, and the best part is, if it doesn't work the way I want it to, if I am afraid it might damage the tranny, I'll just disconnect any wire (or vacuum line) and it is back to the way it is now.
     
  4. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Would you not also want a speed input? I don't know when the trans oil pressure hits 50 psi, but if it does so while in the lower gears, you don't want lockup at, say, 20 mph in second gear (about to shift to 3rd) with light throttle.
     
  5. 72Gold

    72Gold New Member

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    The need for a speed input was what had me concerned in the first place. I didn't want to add the complexity of integrating a speed sensor into the circuit along with the logic of getting it to operate correctly. (I may add a speed generator later to send a signal to a cruise control.)

    However, while researching all of this and trying to keep it simple, I saw a clue about using the Governor pressure port. I looked at the table in my 1985 Ramcharger Service Manual, along with a couple of older service manuals, and all had charts showing predicted speeds for shift points as well as Governor pressures. Since the Governor is directly related to the output shaft speed, the pressure is also nearly linear to vehicle speed. In fact, a vehicle speed increase of 1 mph also means a Governor pressure increase of 1 psi. In other words, the Governor pressure will be about 60 psi at 60 mph. Of course, this will depend on the final drive ratio -- the rear axle ratio and the diameter of the tires.

    This means I can use the Governor pressure port with a good quality pressure switch to cause an effect at a desired speed. Note that Governor pressure is different from Line pressure. There will be no problem of lock-up in gears 1 or 2, even though there can be overlap in speeds. The vacuum switch will ensure there is no lock-up for gears 1 and 2 at speeds lower than the set pressure during hard acceleration.

    I would like lock-up to occur around 50 mph for this pickup with tall gears (2.7) and big tires (29.1 diameter). I will start with a pressure switch set to 50 psi and see what happens. Many of the switches are listed at +/- 3 psi in this range, so it won't be exact. Likewise, viscosity changes will likely impact the lock-up point.

    I am going to try it and see.

    Thank you for the question, I have learned a lot with this issue.
     
    Bob Lincoln likes this.

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