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Thread: 6L80 Reference Material

  1. #11
    Junior Member T2000's Avatar
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    Excellent info - thankyou Joecar !!!

  2. #12
    Joe (Moderator) joecar's Avatar
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    Default Shift curve relationships

    PT shift table relationships:

    basic relationships:
    1->2 curve should be above 2->1 curve;
    2->3 curve should be above 3->2 curve;
    3->4 curve should be above 4->3 curve;
    4->5 curve should be above 5->4 curve;
    5->6 curve should be above 6->5 curve;

    additional relationships:
    3->2 curve should be above 1->2 curve;
    4->3 curve should be above 2->3 curve;
    5->4 curve should be above 3->4 curve;
    6->5 curve should be above 4->5 curve;

    this can be summarized as: the curves must not cross anywhere;

    if they cross anywhere, then you will not be able to predict what gear the TCM selects when the operating point hits the cross.
    Last edited by joecar; August 21st, 2015 at 07:37 AM.

  3. #13
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    Joe - have a question about your previous post, and I'm hoping there is new info on this. I've also been searching the forum.

    How big a deal is it if the lines do cross? I ask because my factory 2015 program has the lines crossing in several spots, and I'm wondering if it's related to the 6L80E being able to directly switch between gears (like a 6>3 shift going 6-3) rather than having to cycle through (like a 6>3 shift going 6-5-4-3). Mine has been attached.

    For anyone else, has anyone got a good 6L80E shift program they would care to share? I'm looking for something for a street vehicle that has excellent shift characteristics, that will still get up and go when I get into it. If nobody has one I can start with, I'll post mine up when I finally get one worked out. The 4.11s did much for drivability, but the stupid trans shifting at 5200RPM makes it feel like it's tripping at the finish line, so to speak.
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  4. #14
    Joe (Moderator) joecar's Avatar
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    Hi Telco,

    Even with the ability to skip gears, the curves should still not cross (i.e. not be allowed to cross).

    When they cross, the crossovers provide the TCM with multiple choices of which gear to select next...
    the TCM/OS will make a decision based on current conditions (which may not be consistent each time);
    different TCM/OS will select different choices (i.e. not consistent).

  5. #15
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    OK thanks. Makes sense, just didn't understand why GM was doing it.

  6. #16
    Joe (Moderator) joecar's Avatar
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    I don't understand why they did it, seems lime they rushed it.

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