When I bought vehicle and I paid for extender warrant and begin to have problem with the brake and radio and transmission. I kept taking my truck back about the problem and they kept telling me they do not see anything's wrong, then my truck stop pulling and they Kirk Brother kept my truck for two week and they said I hade a screw miss out my transmission and they fix it, so I ask them did anyone work on this transmission and they said they did not no. After my warrant expire my brake lock up and Kirk Brother charge me 3,948.90 to fix my brake.

So I went to kirk Brother, they call me about me trade my truck in, after I take it there and they drove the truck and said you have Transmission problem, truck end good shape but they offer me 36,000 for the truck until they found out about the Transmission and they offer me 15,000 for the truck, and I stated to the dealer and was bring my truck to you all and you did no find anything's wrongs Please contact me Frankie D Barnes at 662-515-8709

2018 GMC Sierra Denali - issue first started as a hard shift every once in a while. Then if progressed to every once in a while the shift was so hard I would look in the rear view mirror to see if someone hit me. Now the issue is that the shudder or shaking is so bad you fell it in the whole truck. Smooth roads have not impact on the ride, it seems to be at is worst when you accelerate a bit and the steering wheel bounces all over the place. Then it will subside, it also seems worst after the truck has warmed up a bit, like 15 minutes. I have taken it to the dealer, they claim they can not reproduce... they are just wrong. I has the tires checked out this weekend by a Tire company, they conducted a road Force and balance test on all the wheels. Road Force was good but the balance was off. All corrected as to proper balance, took the truck for a ride down the interstate and well Shudder and shaking is still very much present. Even the tire company Tread Quarters provided me with a Technical Service Bulletin ( #18-NA-355) March 30,2020 on this issue and it is an exact fix to my trucks issue.

I am going back to the dealer and this, no matter what GM lawyers say is a warranty issue, I purchased this truck partly due to the transmission and how smooth it operated and better fuel.

The bulletin claims the issue may be the Torque Converter Clutch (TCC) Shudder. They claim that on the "correction" notice they did not say fix but correction, to have a fluid exchange to HP fluid.

I am going back to the dealer a bit more educated and talk with the Service Manager.

Bought a pre-owned 2018 GMC Sierra 6.2L that ran beautifully at first, around 35k miles the steering wheel started to give a slight brief shudder in cruise control at about 65mph, and shifts a lot less smoother coming from a dead stop 1st-2nd gear. Feels like I'm running over the warning grooves cut into the road along the shoulder. Called the service department at dealership and he says it is out of warranty and will cost me to do a triple flush and refill with new fluid ($200.00) and labor ($150.00) at 36100 miles. You would think GMC being aware of the problem with these transmissions/torque convertors would at least do the initial flush as a courtesy the first time in.