Problem with my A-904-A Torqueflight Transmission

Transmission and Drivetrain Tech

  1. Da"DART"

    Da"DART" Member

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    Hi All!
    Any help or advice would be greatly appreciated.

    The Original transmission was pulled from the car and modified around 1990 when I started the restoration. The car is a 1968 Dart G.T. When the transmission was out I installed a shift kit, deep tranny pan kit and Mopar 2200-2400 stall torque converter. I filled the transmission with Dextron and reinstalled it back in the car. I also change the rear axle ratio to 4.10.

    Fast forward to today. I tried to put the car in gear for the first time. With the car off and up on jack stands I spun the rear wheels by hand and made sure neutral was really neutral, park was park etc. I also adjusted kick down linkage. There was no other adjustment made to the transmission.

    I started the car in park warmed it up for 5 minutes, went through the gears slowly and stopped at neutral. When the transmission pan temperature got to 200 degrees, I checked and adjusted the transmission fluid level.

    The next thing I did was to check if it would go into forward and reverse gear. I first noticed the lack of torque going into all gear positions, it felt like the engine was not running, no positive engagement of the transmission. the wheels start to turn at about 2000 rpm and the wheel speed is only about 3 to 5 rpm.

    Very interested if anyone has experienced this.

    Thanks
     
  2. Dana67Dart

    Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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    So am I'm reading this correctly...

    32 years ago you rebuilt / modified the transmission and it sat un used till today.

    Is that correct?
     
  3. Da"DART"

    Da"DART" Member

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    The engine was rebuilt the transmission was modified. I guess life happens.
     
  4. Ironracer

    Ironracer Gearhead

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    You said you had a stall? Could that be the issue?
     
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    • 408 swinger

      408 swinger FABO Gold Member FABO Gold Member

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      Dang. I wonder if the frictions just plain gave up. Sitting for that long and not immediately putting in neutral to get the fluid circulating.
       
    • Dana67Dart

      Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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      I was thinking 32 years of moisture absorption.

      It is also posable that the OP did not get things back to get her correctly.
       
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      • Ironracer

        Ironracer Gearhead

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        I had a 727 that sat 9 years after a rebuild, an Old School Mopar Bro of mine said the fluid soaks in and ruins stuff. For 300 bucks, I had a local bowtie guy that owns a transmission shop redo it. Or at least he said he did... unlike United Speed World, who Robbed on My Heads! I guess they thought I wouldn't take them back apart when I got em home they only did halfway whatever they did because it still had motherfuking Carbon on half the valves. Supposedly Magnafluxed, valve job. They were off a running motor I don't think they did a damn thing to em
         
      • CudaFactHackJob

        CudaFactHackJob Well-Known Member

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        Five minutes in 'Park', and THEN you checked the fluid level? Good way to fry the bushings out of it.
         
      • Demonracer

        Demonracer 71 Demon 00 Ram 16 Chrysler 300S 05 Caravan FABO Gold Member

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        Looks like it's time to pulls the trans & tear it apart.
         
      • oldkimmer

        oldkimmer FABO Gold Member FABO Gold Member

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        What shift kit did u use? Kim
         
      • AJ/FormS

        AJ/FormS 68 Formua-S fastback clone 367/A833/GVod/3.55s FABO Gold Member

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        You did NOT say that you had a Manual Shift Kit installed. In which case,
        Part-1; With a standard ValveBody;
        the Governor is in charge of when the upshifts occur, no matter in what position the gear selector position is in. In other words ; You put it in manual low, and rev it up, but if the driveshaft speed never comes up, then you will not get any upshifts.
        Therefore, for now, the problem seems to lie in the lack of governor pressure.
        This could be due to;
        A lack of driveshaft rpm, or
        a failed governor or,
        a failed governor circuit, or just plain old lack of fluid or fluid-pressure.
        So then, my first go-to, is a pressure test.
        >This is way too easy, in your case. Just put the trans in reverse. In reverse, full pump pressure is sent to the L/R band and the Hi-drum. At 700rpm, it should clunk into gear, and by 2000 rpm (stall) it should be locked up and spinning the tires furiously. This proves the following parts are working;
        the pump,
        the L/R band,
        the hi-drum,
        the VB, and
        The Manual-valve
        In reverse the governor is locked out.
        So if reverse is working, you just proved everything but the KD-band, is functioning.

        >But if reverse will not work, then, more than likely, the pump is broken. To prove it you only have two choices, a pressure test or a physical inspection.
        But before you drop the trans, if reverse will not work, make sure the manual valve is connected to the external lever, AND also synchronized to the Manual Valve. If the trans goes into park and locks the driveshaft, AND comes out of Park just the same, then they are connected. Now prove that manual-Low on the shifter is synchronized to manual low in the trans . This is usually done by putting the trans in Neutral, and putting the gear selector also in Neutral, then test fitting for a slip-fit of the shifter linkage into the external shift lever, and adjusting the mechanism as may be required. If these are NOT synchronized, then the manual valve could end up between gears and hemorrhaging fluid back into the pan, instead of that fluid going to it's destination.
        And finally, after the above has not solved the problem, then, the L/R servo could have malfunctioned; Pop the pan and VB and do an AIR-pressure test to see if the servo is working and the struts are correctly installed.

        BUT
        Part-2; With a Manual Valve Body, then the Governor should have been bypassed; and the driveshaft rpm is a Non-issue.
        In this case, lack of pressure in Reverse, has to be either;
        a lack of fluid, or
        the Manual-Valve is Not synchronized, or
        a broken pump.
        But again;
        >if you do have reverse pressure, AND BOTH, no Reverse/no Low; the common element is the L/R band. Pop the pan and VB and do an AIR-pressure test to see if the servo is working and the struts are correctly installed.
        Ok so there ya go, see what comes up;
        Happy HotRodding
         
        Last edited: Jun 18, 2022
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        • Da"DART"

          Da"DART" Member

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          Thanks AJ/FORMS for your help.

          I have an O.E valve body and I believe the shift kit is a B&M part no. 10226. I did do a hydraulic pressure test on the line pressure port and rear servo apply port. The result was Zero pressure at 1000 rpm and Zero with the throttle lever position moved rearward. I had previously checked reverse gear at 1000 and 2000 rpm result was very little movement. When I first filled the transmission I did notice that the fluid level had dropped and needed to be topped off from the initial fill. Can I assume the pump is working? There are no strange sounds or smells and the fluid is as new. I think the next step is to drop the pan and inspect the valve body and perform an air pressure test.
           
        • AJ/FormS

          AJ/FormS 68 Formua-S fastback clone 367/A833/GVod/3.55s FABO Gold Member

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          Hang on man, if the pressure in reverse is zero at 2000rpm, then the pump seems to not be working.
          The Convertor drives the pump with those two cut-outs in the hub. When you installed the convertor into the BH, did you remember to engage the pump and the input splines? that would have been TWO convertor-drops.
          Then after the Trans was bolted to the engine, do you recall pulling the convertor towards the crank before or while installing the retaining bolts?
          If these things are not done, the usual result is a broken pump, and messed up pump-house.

          It seems that with the fluid-drop in the pan during the warm-up, the pump was filling the convertor.
          But the reverse-pressure at the L/R servo port, says otherwise.
          So, Ima gonna have to look at the map; back in a sec

          Ok yes this can happen
          Let's prove the pump is working.
          In reverse, the fluid flow is;
          pump to the regulator, to the convertor control valve, to the convertor, to the cooler, then back to the pan. Therefore you can prove the pump is working by cracking the the cooler-line FROM the convertor. Here the pressure might be somewhere between 30 to 75 psi@1600rpm. But you don't actually have to measure it ...... yet. If you have fluid flow, the pump is working.
          Now lets go back to the Regulator valve.
          Still in reverse; fluid flow is;
          from Regulator-valve to the Manual-Valve, to BOTH and simultaneously; the Hi-drum and the L/R servo. Therefore with fluid flow in the cooler line BUT no pressure at the L/R servo, fluid is NOT moving in this circuit or is dumping somewhere.
          As to loss of fluid-flow/pressure:
          in order of most likely, the choices are;
          >failure to synchronizing the manual valve

          >broken cast-rings in the Hi-drum
          >Fallen out-of-place struts, re the L/R band.
          >faulty hi-drum
          >broken L/R band
          >broken L/R servo
          > missing steel check balls at locations 3 or 4
          In reverse, NO other circuits in the VB are in any way working.

          Here is a pic I snagged off the Net, showing the flow in Third gear. It's all I could find. You'll have to use your imagination for reverse. Reverse is the last circuit on the far right of the Manual-Valve.
          In reverse, the Manual-Valve would be all the way to the right, just before the dumping area. Notice that, if stuck between circuits, it would be dumping the fluid straight back into the pan, or attempting to send fluid into one of the other circuits. This is why it has to be synchronized to the gear shifter. and
          We use Neutral because in this position, the shifter has a big window with no gating, so you can align the indicator-needle pretty easily. After that, you need to move the selector to LOW, which is the furthest from Neutral, and make sure the trans is indexed correctly, to the shifter. If the indicator-needle is off, it has to be changed, so don't use it as an absolute guide; instead use the trans detent.
          If after this, reverse is not in the right place, then you have the wrong external lever-ratio down at the trans. A-bodies are different from all others, until somewhere in the mid/late 70s IIRC, when the factory did away with the bell-crank down-rod.


          drive-jpg.jpg
           
          Last edited: Jun 19, 2022
        • 66fyssh

          66fyssh Don't Stop Believin' FABO Gold Member

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          You can pull the line off transmission fluid the off the cooler and turn over the car in Neutral to see if fluid is pumped out. Fluid flows out the fitting on the front of the transmission and back into the fitting on the rear.
           
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          • oldkimmer

            oldkimmer FABO Gold Member FABO Gold Member

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            Some of the valves may be stuck in the valve body from sitting for that long. A lip seal in 1 of the drums could be damaged. That’s a nice shift improver kit. Has its own separator plate. It only works for so many years, was your vb/tranny included in those years? Kim
             
          • CudaFactHackJob

            CudaFactHackJob Well-Known Member

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            This guy has no clue and you're posting hydraulic diagrams?!?!? DUDE, dump some more fluid into it!!
             
          • Da"DART"

            Da"DART" Member

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          • Da"DART"

            Da"DART" Member

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            Today I tried to Tee off the transmission cooler return line and check for pressure, the result was zero. Then removed the supply line to the cooler at the radiator to check for flow and the result was also zero. I assume I have pump failure or improper engagement of the torque converter with the pump. It was so long ago that the torque converter was installed that I cannot recall too much about the installation.
             
          • CudaFactHackJob

            CudaFactHackJob Well-Known Member

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            Dump another quart into it with that line off (engine running) and watch a red geyser go everywhere.
             
          • CudaFactHackJob

            CudaFactHackJob Well-Known Member

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            If your pump was broken, then the fluid level would be WAAAY up the stick. MORE FLUID!!!!
             
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            • Da"DART"

              Da"DART" Member

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              Problem solved! Thanks to all the folks that replied offering advice and help. I decided to drop the pan and remove the valve body and clean it and go over all the adjustments stated in my shift kit instructions. With the valve body out of the transmission, I would also perform an air test on front and rear clutch, kickdown servo and low and reverse servo. Prior to removing the pan I came across a YouTube episode by #moonbuiltgarage who was experiencing the same problems with his A-904. Sure enough when I removed the valve body I could see I had the same issue. There is a tab on the manual lever assy. that was not engaging the manual valve due to too much verticle movement in the manual lever assy. I added an extra washer to the assembly to remove the slop. Tried the transmission and it appears to be working.
               
            • oldkimmer

              oldkimmer FABO Gold Member FABO Gold Member

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              Post some pics of what u did. Let us know after u road test it. Kim
               
            • Ricks70Duster340

              Ricks70Duster340 Child of the King FABO Gold Member

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              I had that same problem once. Someone took the manual valve out and did not replace the washer that goes under the "E" clip so the manual valve would move up and down causing problems. Putting a washer under the "E" clip resolved this. Thanks for sharing your fix!
               
            • CudaFactHackJob

              CudaFactHackJob Well-Known Member

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              ROFLMAO!!
               
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