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Thread: manual shifting reaction speed 8l45

  1. #1
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    manual shifting reaction speed 8l45

    WIth an unlocked TCM, is there a way to decrease the time it takes for the transmission to react to your input through the manual shift mode? Meaning, when I hit the "upshift" button, right now, it takes for ever, to upshift. Same with down shifting, Ill hit the dhown shift button, and then a second or 4 will go by then it will own shift. This occurs anywhere in the rpm/speed range. Id accept it if I was in a spot where it would through the rpms into a dangerous position.

    But yeah, Im just looking for a way to make the trans shift when I tell it to when in manual, and when I hit the buttin. 2018 Colorado 8l45 transmission

  2. #2
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  3. #3
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    I was just reading that when you posted. That thread covers the actual time it takes for the shift to occur.

    I guess my post was unclear. I am trying to find a way to make the start of the shift happen sooner. So the time between when I hit the upshift (or down shift) button and the time the transmission starts its gear shift. The time it takes for the transmission to go from one gear to the next is fine. Its just the lag between me telling it to do something and then it doing it is what Id like to change.

  4. #4
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    Yes, the manual shift switch is wired to the BCM, then data streamed to the ecm and tcm. There is no problem with the speed of time it takes for the switch input to "hit" the computers. The speed of the shift is determined by the pressure control and design of the transmission and the design of the controllers/computers. You are limited as to what you can accomplish. Here is additional information. I would like my FWD (Malibu) to shift like a RWD (ATS-V) in manual mode, but the design is the limiting factor. Hope this helps. You could post a tune and log, etc..
    Attached Files Attached Files
    Last edited by DGS; 01-05-2019 at 01:11 PM.

  5. #5
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    You have crushed my hopes and dreams today! Lol!

    I wonder if someday people will start cracking the bcm like they do the TCM and ecu. It would be nice to transplant the shifting abilities of the other platforms into non “performance” vehicles.

    I have the Colorado ZR2, and I can’t believe how not performance it is. One would think that their “prerunner” truck would have the more performance oriented transmission controls...


    So basically, until I learn how to use a computer and crack the bcm and figure out a way for the Colorado bcm to use the Cadillac V series transmission manual shifting perameter... I’m stuck with slow reaction times but fast shifts...

    I’m too old and impatient to learn coding.

  6. #6
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    When you spend $75 - $100 G, you get performance coding and design.
    Last edited by DGS; 01-05-2019 at 01:33 PM.

  7. #7
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    I had my redline on my vehicle up into the 7,000 rpm range and it would hit near 8,000 with the shift delay. I guess one could have the transmission built for some gains, but would not be worth the money. You could convert to a manual transmission.

  8. #8
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    Id pee myself for a manual conversion. Not sure what the changes to the BCM would be, or how that would be accomplished. But the did offer the truck with a 4 cyl and a 6 speed manual. So the pedal assembly is available easy enough, and the center console trim for the shifter...

    Throw someting strong with a transfer case in there.... I do dream of a 6.2 swap...it would be awesome with a manual.