2018 CT6 8 speed transmission problems

This topic has 5 replies, 5 voices, and was last updated 2 weeks, 3 days ago by Windemon.

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February 3, 2023 at 10:51 pm #94707

redcruise
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I have had my 2018 CT6 Luxury for about a year. It has the 8 speed transmission that gives choppy shifts when the motor is cold. This is apparently very common and the dealer has told me that since it shows no codes on the diagnostic, nothing can be done. Apparently such a common problem, that the transmission was redesigned in 2019 to make the 10 speed transmission. Does anyone have comments? Any thoughts of a class action suit?

February 4, 2023 at 7:32 am #94711

mjdart
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General Motors had significant issues with the 8-spd transmissions installed in Corvettes and Camaro vehicles. A friend of mine recently bough a 2015 Corvette 8-spd (7K miles) and his car started “shuddering” from the transmission. He found there is a class action lawsuit from issues with this transmission. Records showed his car had the torque converter replaced in 2016 trying to correct the problem. Since then GM has found it was the fluid causing the problem as it seemed to have an affinity for attracting moisture. He had the dealer flush the transmission 3 times and refill with the new fluid designed to correct this issue. He’s told me it seems perfect now, but this was a $600 repair.

February 4, 2023 at 9:42 am #94712

redcruise
Participant

Thanks mjdart
I will contact my dealer with the suggestion. Car was a cpo so still under the last year of warranty.

February 22, 2023 at 4:48 pm #95137

Caddy22
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I have a 2019 ct6 cadillac & I feel like my transmission jumps also. The dealership said nothing was wrong with it. Also the auto start & stop system should be smooth. It makes my car jump hard when it starts back up.

February 25, 2023 at 7:53 am #95205

jbriant
Participant

I have the 2017 CT6 platinum, my only disappointment with this car is the transmission. I got it used with 20k miles.
I noticed shifting issues when I started to drive it. I was still under warranty for the drivetrain so I had my local dealer
check it out. After a number of iterations, ended up replacing the transmission. As I have researched this this transmission
has issues with design. The poor shifts are usually 1-2. It doesnt do it all the time but more than I would like. I live with it because
i really love the car, 3.0TT, 34 speakers, active suspension, a black on black paint and interior. The 20 inch wheels, I get 30mph on
he highway.

March 14, 2023 at 4:37 am #95860

Windemon
Participant

I had fluid changed. Still sometimes rough shift 1 to 2.
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