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GM Reported to NHTSA Investigation of C8 Transmission

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  • #46
    Originally posted by LincolnL View Post
    FWIW. I test drove a red 20 1LT last week with 7k miles on it for sale at my local Audi dealership. Even though i was desperate to finally get my C8, i passed due to the transmission being not right. It upshifted perfect under load, but refused to upshift properly in full auto mode. The RPMs would just hang way too high with foot off the throttle and no load, then kind of "clunk" awkwardly and eventually upshift. So i bought a new 22 2LT. Hoping they'll have it sorted out by next months builds
    FWIW I have been driving mine for over a year and it hangs at high RPM's just like you are describing when I am in TOUR mode and mash the throttle from a rolling start, get up to 60 or 65 and suddenly let OFF the throttle. It sits at HIGH RPM's, thinking I'm wanting to continue accelerating, waiting to shift UP, instead I'm off the gas and it takes what seems like forever to realize I'm off the gas and finally shift UP. It is a more abrupt shift, because it's going up 2 or 3 gears. I consider it normal.
    2020 1LT |Torch Red/Black | MSRP $59,995 | DOB=8/31 | Home on 9/24.
    Splash Guards, Cargo Nets, All weather Jake Floor Mats and Cargo Area Liner, and Front Grille Screens behind grilles.


    • #47
      Originally posted by jackfrostpdx View Post

      Yeah I've experienced the Tour mode 'rev hang' around town when I'm heavy on the throttle and then pull off abruptly. Always assumed that's just the DCT programming trying to guess my intentions,
      This is how I've experienced it... driving around town in Tour/Automatic, accelerating sharply when I want to do a quick lane change, but then letting off the gas so as to not gain too much speed--or to slow down if I'm coming up on another car. I was probably in 1st or 2nd gear. The first time I noticed it was right after my first service and DCT filter change. For a moment, I wondered if there was a connection, but I decided it's normal.

      I think it's only happened twice, and I don't recall the shifts being "clunky," just slow to happen, so I figured it must be due to the programming in the TCM and not a problem with the DCT itself.
      Last edited by /Bear/; 11-19-2021, 08:44 AM.


      • #48
        Originally posted by John View Post
        There are literally 50,000+ C8’s whose DCT’s work perfectly. Mine has not had one less than excellent up shift nor downshift since day one.

        There’s something wrong with that used one. They should not even try and sell it until perfectly fixed.
        I also have not had one issue with my early November 2020 build of my C8. Nothing at all with the car, including the DCT. The car has been fantastic.
        2020 Torch Red Z51, Mag Ride, 2LT, Two tone GT2 seats (Black Red), Front Lift, Engine Appearance, Red Engine Cover, Red Calipers, Carbon Flash Wheels, Mirrors/Spoiler, Black Lugs, R8C Museum Delivery


        • #49
          I have experienced the transmission hanging higher in the rpm range for a bit before upshifting similar to others. Usually when I accelerate quickly to pass or something. Happens in tour and sport (I dont generally use track). I have assumed it's normal, at least while the car is learning. But as I mentioned in another post mine may have an issue with the adaptive transmission computer (I've already had a new transmission and check engine light twice in the first 1000 miles)

          To highlight the good customer service from GM im getting they did just inform me I will be getting a free extended warranty to 60k miles and free maintenance to 45k miles!