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Thread: Clunky 5-3 Downshift 6l80

  1. #1
    Potential Tuner
    Join Date
    Mar 2024
    Posts
    1

    Clunky 5-3 Downshift 6l80

    So I'm very new to tuning and thought I'd give it a shot on my supercharged Hummer H2's 6l80. Mainly just trying to mitigate some of the clunkyness and make it last longer. I had a trans go out at 30k, one go out with 70k, and this one's got 40k on it. Figured I couldn't make it worse. The only things I've changed so far is the torque converter minimum slip so it stays locked up when cruising, and I adjusted the part throttle shift scheduling to make it feel like less of a turd.

    The issue I'm trying to resolve now is a clunky 5-3 downshift. Part throttle and wot. It's always been that way. Surprisingly the 6-3 downshift is smooth as butter. Slow, but it doesn't make you need a chiropractor like the 5-3 shift. It legitimately feels like running over a landmine. It's my understanding with the design of the trans that the 6-3 is supposed to be clunky not the 5-3 as it doesn't have to disengage the 4-5-6 clutch right? How can I smooth this out?(2) BC WOT and Part throttle shift mph normal only.hpt

    Also, let me know if the attachment works. This is my first post.

  2. #2
    Advanced Tuner
    Join Date
    Aug 2023
    Location
    SoCal
    Posts
    452
    None of the kickdown or coast downshifts are supposed to be clunky, I would take it back to the company that rebuilt it and have them fix it instead of trying to Band-Aid it with programming. Also I know it's too late now but if it ever has to come back out again, do yourself a favor, and install our 6l80-TOW&PRO Reprogramming Kit™ in there and your problems will go away permanently and it will drive so much better.
    Last edited by TransGo Robert; 03-20-2024 at 07:52 PM.
    Robert Moreau
    Technical Sales and Marketing Support Specialist
    TransGo
    2621 Merced Avenue El Monte, CA 91733 USA
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