Torque Converrters

Discussion in 'Big Block Cadillacs' started by richie49, Jan 25, 2020.

  1. richie49

    richie49 Active Member

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    While working on my car I came across a question I didnt even know to ask. i replace my converter a while back,took out the gm one and put in a Hughes 12 inch 2500 stall converter. Well I stripped teeth off the flywheel and pulled it apart to replace it.Got a new flex plate from cad company with new arp bolts.bolted up the trans and went to bolt up converter and it wouldn't fit against the flywheel.The new bolts were too large on the heads to fit close to the converter. The question that I didnt know was if the converter will fit against the flywheel for my application. Apparently for the cad the stock converters have more of a bell indention on the flywheel side for the bolts too fit without hitting against the converter. Getting a smaller converter 12 inch from 13 inch creates a problem. After putting the old bolts back in the flex plat was still .10 away from the converter. I noticed the converter and flywheel seperate when I loosened up the bolts while removing the old flywheel. I didnt notice it when I first put in the converter for some reason,no telling why brain fart or something.
    A lot of you may already know this and dont think of it when working with converters but it was new to me.It may only be with the Hughes converter I dont know.I have never seen this talked about or mentioned before. I'm just letting everybody know about this so they can check this out and keep from getting messed up or going thru extra labor on this.
    richard richie49
     
  2. 5one9

    5one9 Active Member

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    How about some pics. I just put a new SFI flywheel on mine with a 9.5” converter and it is fine. Are you saying that your converter has the smaller bolt pattern?
     
  3. 5one9

    5one9 Active Member

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    I assume that this is what you are talking about. The belled part being tight against the smaller pattern bolt hole? What size bolts are you using 3/8” or 7/16”? If 3/8” you could use header bolts.
    My flywheel holes are 7/16” so header bolts would be kind of sketchy
    4BF8717A-A221-48F9-81E3-AD9FADF29DA4.jpeg
     
  4. Cadillac Kid 1

    Cadillac Kid 1 Well-Known Member

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    Any possibility that I have the flex plate on backwards
    Greg Surfas
     
  5. 5one9

    5one9 Active Member

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    I tried mine both ways. It only goes on one way, and only on one side.
     
  6. richie49

    richie49 Active Member

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    The flywheel can only go on in one way. With the flywheel bolted up the bolts at the crank hit against the converter before the converter sets against the flywheel.
    I talked with cad company and he said that the converter is too small at the place where it should fit over the crank bolts.He said the stock one is larger 13 inch which is true. My converter has both bolt paterns 10.75 and 11.50 and is a 12 inch converter. The snout on the converter is going into the crank .Doesn't the chevy engines have a smaller crank end at the flywheel?
    So maybe it's more compatable with a chevy,I dont know. Like I had said I never heard about this issue before.

    Richard richie49
     
  7. 5one9

    5one9 Active Member

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    I don’t know. I just pulled a 12” converter out of mine without issue. Maybe just certain converter cores have problems.
     
  8. kzhurley

    kzhurley Active Member

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    When I put a 4l80e trans behind my 500, same issue. I ended up needing 3/8 spacers between the flexplate and converter. The 4l80e converter wouldn't even sit flat with no bolts at all.
    Been fine for 3 years now. Just bought good converter bolts.
     
  9. PJ McCoy

    PJ McCoy Well-Known Member

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    Kzhurley is right, Is your Hughes TC a BOP banded? there is a difference. I almost bought a 2600 stall Hughes with a dual bolt pattern. Then I called Hughes. Great folks.
     
  10. 5one9

    5one9 Active Member

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    Man am I glad that this thread popped up. Your misery ended up being my saving grace. I haven’t yet put my engine back in yet so today I laid my 9.5” converter on my new SFI flexplate and lo and behold, I only have 0.250” between the converter body and the flexplate bolt surface. I use Ford manual flywheel bolts because they are 3/4” head instead of the smaller GM bolts. The issue is that the head is 0.310” thick which means I have the same issue that you have. The GM bolts are even thicker. I chucked one up in my hand drill and spun it against my bench grinder and ‘lathed’ it down to 0.230” thick. Problem solved! I’m darn glad to figure this out outside of the engine bay.

    I’ll probably throw in some 0.062” washers for good luck. I’ve done it before. The converter hub doesn’t go more than about 0.150” into the crank to begin with so I won’t get too carried away.

    Anyway, know that you helped a forum member toady. Thanks.
     
    SHAKEDOG likes this.
  11. Cadillac Kid 1

    Cadillac Kid 1 Well-Known Member

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    Regarding the nose of the TC into the crank, I had a TCI converter that did not extend far enough so the thing shook itself to death. TCI replaced it with one with a longer nose. I do not recall how far the nose should go into the crank, but 0.150" "seems" a bit shallow.
    Greg Surfas
     
  12. 5one9

    5one9 Active Member

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    I'm not including the bevel, which has no value. It's probably more like 0.250"
     

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