5.9 Magnum to replace Older 360, flexplate?

Transmission and Drivetrain Tech

  1. hillsidehemi

    hillsidehemi Member

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    I have a 64 Fury with a later 70's very tired 360 in it. It has a pretty much stock newly rebuilt 727. Attached to it. I want to install a 2000 magnum 5.9 converted to carb in place of it. What do I need to do for a flex plate? Can I use my older flexplate and Torque converter? Is there a conversion flexplate? Thanks
     
  2. goldduster318

    goldduster318 Overzealous Car Modifier

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  3. hillsidehemi

    hillsidehemi Member

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    So I can use my current converter with the weight knocked off of it with this flexplate. That sounds great. Does this mean I could use my converter then with the stock 5.9 flexplate? I see that the bolt pattern on a Magnum flex plate is symetrical and I would have to file one hole for the older converter. Does it matter where the weight on the flexplate is compared to where the weight on the converter was removed? Thanks for any info.
     
  4. goldduster318

    goldduster318 Overzealous Car Modifier

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    stock 5.9 flexplates do not have the weight on them, they are still on the torque converter for the 5.9, but this is a different weight than the older LA 360 that you had before. The weight has to be in a specific spot.

    So your best idea would be to knock the weight off of your converter and then buy that B&M flexplate. Then it will work without issue or headache.
     
  5. hillsidehemi

    hillsidehemi Member

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    That is what I will do, thanks alot for the information.
     
  6. LXguy

    LXguy Well-Known Member

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    My 2000 5.9 Magnum most definitely has weights on the flexplate.
     
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    • goldduster318

      goldduster318 Overzealous Car Modifier

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      That was a change they made sometime in the late 90's. We put a 94 360 magnum in a 97 dakota and it did not have weights. Its best not to use the late model flexplate with an older trans anyway.
       
    • venomvpr900

      venomvpr900 Well-Known Member

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      I used the mopar performance flexplate with mine and it is weighted and the TQ converter is neutrally balenced.
      On a 2000 5.9 it will be balenced with the flexplate MP also offers a weight kit for your TQ converter if you want to run a non-weighted flexplate
       
    • Abodysrule

      Abodysrule Well-Known Member

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      OK, so fast forward to today. If I buy a 360 Magnum crate motor which comes with a weight balanced flex plate, then I need a neutral balanced torque converter. Does the old type converter work, i.e. take off the weight, or do I have to buy a special torque converter? I'll either use a A904 or 727
       
    • 70aarcuda

      70aarcuda Master Hoader of SBM FABO Gold Member

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      Any converter with no weight on them that fits your tranny
       
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      • Abodysrule

        Abodysrule Well-Known Member

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        Great, and I rat tail file one hole on the plate to make align with the torque converter thread hole, as I understand it, right?
         
        Last edited: Aug 20, 2021
      • Abodysrule

        Abodysrule Well-Known Member

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        Can somebody explain the relationship between internally balanced engines and externally balanced engines and the torque converter having a weight or not? Here we are saying remove the weight for the 360 Magnum, as it needs a neutral balance torque converter, but I thought the weight on a torque converter was to rotationally balance it in the first place. What am I missing? Thanks all.
         
      • Bobzilla

        Bobzilla Well-Known Member

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        External balance means there is offset weight added outside the rotating assembly, typically some at the rear and some at the front. This is how the 5.9 Magnum is setup.
        When people say run a neutral converter, they are saying this ONLY when the necessary offset weight is on the flex plate instead of the converter, not with a symmetrical or neutral flex plate.
         
      • Abodysrule

        Abodysrule Well-Known Member

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        Oh, I see so one knocks the weight off the converter to make it neutral, since the flexplate for the magnum has a weight for balancing, right?
         
      • Bobzilla

        Bobzilla Well-Known Member

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        Yes, exactly correct for 5.9 Magnum.

        The 5.2 Magnum was internally balanced from the factory, so it does not have weight on the converter, flextplate, or harmonic balancer. They are all neutral.
         
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