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J-type overdrive not disengaging

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  • J-type overdrive not disengaging

    As the title says, the overdrive engages fine, but will not disengage most of the time in my '73.
    Things I've done so far:
    I have swapped the solenoid with a known good one.
    I replaced all of the o-rings accessible from the filter plate, so all except the plungers.
    Cleaned both filters, they were not terrible.
    Drained and refilled with 30ND oil (has worked fine with this at least five years.)

    What gives?
    Thanks in advance for your words of wisdom


  • #2
    i will be following this thread closely, as the J-Type in my 73 started doing the same thing last year, after years of good service.
    Does your dis-engage after cooling down?
    CF1634U+O Pimento/Chestnut
    2nd owner, since 1975
    Now in Fair Oaks, CA


    • #3
      Going off the top of my head here though, but isn’t there a process to set up the plunger and actuating arm by using a drill bit as a guide on the side opposite the solenoid?

      81 Alfa Romeo Spider Veloce, 81 Triumph TR8
      73 Triumph TR6 CF4874UO, 68 Triumph TR250 CD5228LO
      62 Triumph TR4 CT6716LO, 60 Triumph TR3A TS69891LO
      60 Triumph TR3A TS64870LO, 59 Triumph TR3A TS44836LO


      • #4
        what you describe is for the atype overdrive,they are talking Jtype here
        make sure you trannie has the right amount of fluid . When I put oil in a jtype on my workbench,I tilt the trannie back so the oil gets in the overdrive


        • #5
          If it were me, I would check these engage and disengagement functions with the ignition on but the engine off. You can hear the solenoid clicks. I’d try this in each gear position too to check for status of the interlock switches and other electrical issues. Also, Jay Holecamp sells a nifty OD pressure gauge that threads right into the side of the J type. It’s under. $75 as I recall. This gauge would confirm if it’s a electrical or hydraulic issue IMHO.

          I have a logic overdrive controller which makes the electrical tests a snap for my J type.

          I also use the Redline MT gear lube. It leaks more easily but man is it ever smooth running and engagement.
          1974 TR-6 Logic Overdrive


          • #6
            Crap I was just in St Louis & have a gauge for the J-type (purchased from Jay). Brand new. If ya wanna borree it lemme know


            So much rust, so little time

            64 TR4 Overdrive Surrey
            67 GT6 Mk1
            68 TR250 Soon to have Overdrive & Surrey
            71 TR6 Hardtop Soon to have OD
            81 TR8 Injected Automatic...the LAST Automatic


            • #7
              here is what I know, as this is a regular issue for me.

              but before I rattle, know this. if the car is stuck in overdrive, don't back up. repeat. let the car sit until the OD disengages.

              I run 30wND. I also have modified my OD with vovlo internals. I had a few threads back in the mid 2000s when gas was 4 a gallon. Got hooked up with a former line assembly guy for laycock, who now works for some brit transmission service in england. in all this, i buy a volvo OD set - essentially the entire mechanical internals. its different from the TR set - but not much. lowers the RPM than what we have, slightly.

              but i began having this issue after my swap. I was told this might be due to the tolerances. this big steel wheel moves back and forth inside that housing, and my guess, for me, was that my replacement was a few thousands bigger than what came out. In time, my expectation was that this would get better. and, with 30wND so cheap, i could swap oil each year, discarding worn oil and debris until that improved.

              i still have the issue. and now, I wonder, if its 30wND.

              what i believe:
              i don't think its solenoid or anything related to electrics. i do believe that is completely mechanical.

              my work around:
              i tend to only get this with highway driving over 15 minutes. the longer I drive, the longer it tends to pop out. I know when driving on the highway that when i exit, and need to park, I want to park in a place that i can drive forward to leave. like a gas station at the pump at the end. or in a parking lot, a pull through spot. but it forces me to hunt for this stuff when i exit a highway. I also tend not to use it as much in town, and if i do, i pop in and out of OD like im shifting gears - 3rd gear up and down on 40 mph streets with lights, for example.

              I don't like putting additional stress on the clutch when leaving a light in 1st. its a feathering, and in time, this won't help with clutch wear, but so far, i think its ok, and with more attention to pacing for green lights and general awareness, i do my best not to be at a complete stop, especially on an incline.

              speaking of incline.
              i call it "sticking", and if the stick isn't too harsh, i can usually find a bit of incline, stop, let the car roll back a touch, feel the OD lock, and sometimes, after a few of these, it will pop out. but I would only do this with the car out of gear, not loading it with any engine thrust.

              I was told that some whacks on the OD housing with a rubber mallet will help. that involves getting out with a rubber mallet, in a low profile car, and trying to swing a rubber mallet with 6 inches of clearance.

              my plan.
              well, before this thread, grin, bear it, and continue until my OD polished itself to a clearance that fixed itself. now, knowing, or assuming others didn't modify their JOD, and are having similar issue, I think its time to call John at Quantum and tell him many are experiencing this issue - see what he says, and how to improve.

              some will say that switching to royal or the synthetics is good for this, and fixes it, but, it goes back to internal pressures, and what is overall healthy for the gearbox. I am also told that the synthetics produce the pressure, creating leaks, which we all have worked on and have improved with the little things, like the top cover vent hole clearance.

              I hope we hear from more JOD owners and work together on this solution. thanks for sharing.


              • #8
                Chris, I have been running 30wt nonD in my A-type for about 10 years now - no issues. So I don’t think that’s it. I would do the electrical tests Mike suggested first just to rule that out and make sure the solenoid is adjusted as per spec. Then if it’s still doing it, I would disconnect the power to it to make sure it doesn’t energize and get damaged in reverse until I figured it out. From there I would call John and talk to him.

                I72 Pimento w/overdrive


                • #9
                  Lou, deep down I don't think its 30ND either, but I will look at more of the electrics and get John involved in a quick chat this week. I agree that we need to check all the possibilities. This upgrade? new now to a point where others are involved and experiencing similar issues. Now 2020, and I reckon John Espizito ran this test 15 years ago? I could be less lazy and go confirm that on Quantum, but it moved some cheese, and now its more common with owners opting for 30wND. And, we have to assume that a JOD will grow into an issue like this, or there are expected locking issues as we continue to move forward. In other words, we all have locking overdrives that release when cooled down, but the cause may be different. or the same, hell I don't know, which is why we are waxing on this. It just hit me that my OD will be locked if I take the key out, or shut the car down. Does that impact an electric issue of stuck solenoid? My assumption there is, the solenoid could be stuck - that is a mechanical devise, or whatever internal plunger...rig...that would hold my sunwheel assembly in that position.

                  Great notes Lou - and I hope we can all keep the chatter up, find others struggling, and get a best practices in place - sure, MT and other synthetics should be an option.


                  J-type overdrive not disengaging




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