Cita de Invitado en septiembre 25, 2026, 7:00 am

Posted a few weeks back about my Denali shifting hard from first to second and I got a bunch of replies telling me to check the fluid first before panicking. Turns out that was exactly it. The fluid was dark and way past its life, and whoever had the truck before me clearly never touched it. Did a proper flush with the correct fluid and the thumping is basically gone, maybe a tiny bit noticeable when cold but nowhere near what it was. I also had them check the torque converter while they were in there and it looked fine which was a massive relief. I had checked out a page where you can learn more about GMC gearbox repair here during my research, but honestly the advice I got on this forum is what pushed me to start with the simple stuff first. If your truck is shifting rough, do not assume the worst. Start with the fluid.