Unbalanced converter?

Discussion in 'The "Juice Box"' started by Deer, May 30, 2019.

  1. Deer

    Deer Well-Known Member

    I was talking to a mechanic and mentioned that I can’t find the reason for the vibrations on idle.
    And he answered me that its almost always the converter causing vibrations.
    I added that my TH400 comes from a much newer Cadillac.
    Which he replied that I should find a th400 from a Buick with matching year and that they were balanced for matching the engine.

    Would you agree to this?
    Aren't all converters balanced individually, no matter what engine they were put on from the factory?

    (I just know that the TH400 is newer, I don’t know if the converter is replaced or original.)
  2. StfSocal

    StfSocal Well-Known Member

    I would agree and disagree with the mechanic. While I don't believe that it matters which TH400 the converter came out off/went in to, it is possible that it could be off balance. Like a manufacturing defect. More likely though, I would say that, if the vibration is indeed from the drive-train, it might not be siting flush with the flexplate. That could cause vibration in the converter. How sure are you it is indeed coming from the drivetrain?
  3. telriv

    telriv Well-Known Member

    Try unbolting the flexplate from the converter & push back the converter to clear the flexplate then start the car. IF the vibration is gone it's the converter is out of balance. IF the vibration continues it's something else. Maybe the harmonic balancer.
    GranSportSedan likes this.
  4. Deer

    Deer Well-Known Member

    I have tested to replace the balancer, timing cover, timing chain & gears, distributor, coil, sparkplugs and wires with new parts. Replaced my Holley with a rebuild Rochester 4MV. Carefully adjusted all. The compression looks good. I bought cylinder leak down tester tool but I haven’t done the test yet. And consider to check and adjust the valves – but first run some fuel additives if it would do some magic.

    Push back the converter and start the car sounds like a good test. Thought I had to remove the converter completely.
    Last edited: May 30, 2019
  5. Matt69olds

    Matt69olds Well-Known Member

    Try “reclocking” the converter position on the flywheel. Try flipping the driveshaft U-Joint 180* in the differential yoke. Sometimes little tricks like these can help “tune” out annoying vibrations. Are the engine and transmission mounts in good condition? If the rubber in the mounts is soft, the mounts can ground out together and transfer noise and vibration.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    If you think the converter is causing your vibration, and pushing it back works, mark the converter and flex plate, and then rotate the converter 1/3 turn and bolt it up. See if that helps. You can do it one more time. The third time, you'll be back to where you were.
    docgsx likes this.
  7. Deer

    Deer Well-Known Member

  8. Deer

    Deer Well-Known Member

    Are Anchor mounts renamed Pioneer mounts? They have almost the same article number;
    Transmission: Pioneer 622378 or Anchor 2378
    Engine: Pioneer 602291 or Anchor 2291

    Which is best, Anchor or Pioneer?
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I don't think it makes any difference at all. If your mounts look good, I doubt that is the source of your vibration.

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