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Thread: Transmission jerk on downshift 3nd to 2nd low Speed no pedal gas

  1. #1
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    Transmission jerk on downshift 3nd to 2nd low Speed no pedal gas

    Hi,
    I have done about 1200 miles after the total rebuild of the gearbox, I am enjoying this splendid car with my family. During testing I find only one problem: the transmission jerks when hot when I leave the accelerator pedal at low speed in 3rd gear. it should shift to 2nd gear but it doesn't, I don't know what to do. the Governor was also replaced for safety. can you help me? Thank you

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  2. #2
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    Quote Originally Posted by alexdmc1 View Post
    Hi,
    I have done about 1200 miles after the total rebuild of the gearbox, I am enjoying this splendid car with my family. During testing I find only one problem: the transmission jerks when hot when I leave the accelerator pedal at low speed in 3rd gear. it should shift to 2nd gear but it doesn't, I don't know what to do. the Governor was also replaced for safety. can you help me? Thank you

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    P.s.

    When coasting to a stop in 3rd gear, there is a very noticeable jerking sensation like something in the transmission is grabbing then letting go repeatedly. It doesn't do this if I manually shift it into 2nd gear or neutral.

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  3. #3
    Motors about after dark Michael's Avatar
    Join Date:  May 2011

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    My VIN:    Banged your VIN'S mom

    Have you adjusted the governor cable and set it to the proper clearance?

    If so then you probably need to build a set of test lights and see what the computer is telling the solenoids to do. After reading again, it sounds like your solenoids are really acting up (mine acted similarly when my second computer failed). It wasn't jerking, the computer was telling the car to shift like 5 times a second which made it feel like it was jerking.

    Just because you replaced the computer, don't dismiss it. I went through like 3 brand new rebuilt computers before I got one that held up. The first two lasted about 2-400 miles each.
    Last edited by Michael; 05-14-2024 at 08:17 AM.
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  4. #4
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    Hi Michael.
    Very nice to hear you.

    yes, I adjusted the Governor cable so that the RPMs were higher. but I remember even adjusting the cable correctly (see manual) the problem was still there... the Governor was replaced about 1200 miles, 8 months ago. could he be the flaw? I see that with a cold engine it behaves much better.....



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  5. #5
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    Location:  Northern NJ

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    My VIN:    10757 1st place Concourse 1998

    If you notice the shift computer, aka governor, shifting differently when it is hot, it is typically bad solder joints inside the shift computer. When you take it apart you may also find 2 of the large capacitors have exploded, they should be replaced.
    David Teitelbaum

  6. #6
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    Thanks for your advice.

    I'm sorry to have to dismantle the Governor purchased a few months ago. it's a long job.

    Is it possible for a newly built device to have these defects? I take this opportunity to ask you if the level of the ATF overfill liquid can create this lack of hot climbing? Can excess oil lead to overheating? overheating can lead to gearbox control errors. Why? manually (with lever 2-1) the gearbox shifts fabulously.....

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  7. #7
    Senior Member
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    Location:  Northern NJ

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    My VIN:    10757 1st place Concourse 1998

    Overfilling can lead to all kinds of unusual problems so it is important to check the level as explained in the Service Manual. Don't forget you should also check the level in the final drive too. When checking the automatic transmission you should do ALL of the in car checks including the shift linkage, control cable to the shift computer, line pressure, check the transmission mounts, fluid levels, etc. Make sure all of the wiring is secured away from the hot exhaust pipes and the vacuum line to the vacuum modulator is not leaking.
    David Teitelbaum

  8. #8
    Motors about after dark Michael's Avatar
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    My VIN:    Banged your VIN'S mom

    In my case, it wasn't the capacitors that failed, there were two diodes in the governor that failed.

    Like I said earlier, build yourself a light kit and go for a drive. It will not take long for you to either rule out a governor, or identify it as the culprit....even if it was just replaced last month.

    My governor actually worked when cold....very cold. After a few miles, it reared it's ugly head.

    Once you have your test lights built, (I ran long wires and affixed mine to the sunvisor) you will know with a high degree of certainty, where the problem lies.


    Edit: which governor did you use? Ed's? DMCH? (They are the same) or Marty's?

    I'm not knocking Marty's builds. We are keeping a 40+ year old car with Lucas electronics on the road here. I'm not going to call anyone out who is actively trying to find answers to problems. It's just the nature of the beast.
    Last edited by Michael; 05-14-2024 at 11:54 PM.
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  9. #9
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    Quote Originally Posted by Michael View Post
    In my case, it wasn't the capacitors that failed, there were two diodes in the governor that failed.

    Like I said earlier, build yourself a light kit and go for a drive. It will not take long for you to either rule out a governor, or identify it as the culprit....even if it was just replaced last month.

    My governor actually worked when cold....very cold. After a few miles, it reared it's ugly head.

    Once you have your test lights built, (I ran long wires and affixed mine to the sunvisor) you will know with a high degree of certainty, where the problem lies.


    Edit: which governor did you use? Ed's? DMCH? (They are the same) or Marty's?

    I'm not knocking Marty's builds. We are keeping a 40+ year old car with Lucas electronics on the road here. I'm not going to call anyone out who is actively trying to find answers to problems. It's just the nature of the beast.
    Hi,
    Ed's Governor.

    I confirm that during the first kilometers I have no problems. I will first install the test lights. I will update my post soon. thank you all

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  10. #10
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    Quote Originally Posted by alexdmc1 View Post
    Hi,
    Ed's Governor.

    I confirm that during the first kilometers I have no problems. I will first install the test lights. I will update my post soon. thank you all

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    https://drive.google.com/file/d/19xg...w?usp=drivesdk

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