2018 CT6 8 speed transmission problems

This topic has 10 replies, 9 voices, and was last updated 2 months, 3 weeks ago by kleslie.

Viewing 11 posts - 1 through 11 (of 11 total)

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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
Participant

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
Participant

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.

August 2, 2023 at 9:33 am #98834

Djbrazostx60
Participant

I paid almost $90,000 for my Cadillac CT6 PLATINUM off the showroom floor. Before it reached 15,000 miles it was having shuddering with the transmission. Initially,they tried to say it was normal, but finally admitted there was a problem. Changed transmission fluid x 3. Each time it worked about 1 week then the shudder returned. Research shows Cadillac knew these transmissions were faulty but still approved 800,000 to be installed in vehicles. I only have 28,000 miles currently and the shuddering happens continuously. It’s so irritating to pay that much for a vehicle to end up with constant transmission problems. I still have 1 year left on the powertrain warranty. Does anyone know of any Class Action Lawsuits going for this issue? Or does anyone have any suggestions on what I can do or say to the Cadillac service that would make them replace this piece of crap transmission?

August 2, 2023 at 9:34 am #98835

Djbrazostx60
Participant

I paid almost $90,000 for my 2018 Cadillac CT6 PLATINUM off the showroom floor. Before it reached 15,000 miles it was having shuddering with the transmission. Initially,they tried to say it was normal, but finally admitted there was a problem. Changed transmission fluid x 3. Each time it worked about 1 week then the shudder returned. Research shows Cadillac knew these transmissions were faulty but still approved 800,000 to be installed in vehicles. I only have 28,000 miles currently and the shuddering happens continuously. It’s so irritating to pay that much for a vehicle to end up with constant transmission problems. I still have 1 year left on the powertrain warranty. Does anyone know of any Class Action Lawsuits going for this issue? Or does anyone have any suggestions on what I can do or say to the Cadillac service that would make them replace this piece of crap transmission?

October 18, 2023 at 9:47 am #100235

georgem456
Participant

I had a similar problem with my 2018 CT6. Took it to the dealer and complained. My dealer found a service bulletin regarding this problem and flushed the transmission at no charge even though regular warranty expired but drive train warranty was still active. Car seems to drive better.

December 12, 2023 at 11:36 pm #101163

tsprimont
Participant

GM issued a Service Bulletin for this issue. I brought my 2018 CT6 TT to the dealer who applied the service bulletin, under warranty, and it fixed the problem; no issues afterwards at all. The fix; the service tech flushed the transmission fluid thrice, and used a different viscosity fluid.

February 3, 2024 at 9:44 am #102040

kleslie
Participant

I have a 2017 CT6 limited. I bought it CPO with 25,000 miles in it. it started shuddering at 35,000. They replaced the torque converter (no charge). I had some leakage around the rear differential and they replaced the seals. The auto -stop jerking thing is something you have to live with if you want good gas mileage and this big -ass car gets great gas mileage. I wish Incould import a 2024 from China. This car is the bomb!❤️
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