C8 problems
Burning Brakes
Joined: Sep 2020
Posts: 807
Likes: 562
Not to be a nudge, but being a guy who has collected Maserati for 35 years. I'm just going to tell you, Maserati hasn't built a car worth the tires they sit on since 1981. Demise of Maserati was the curse De Tommaso, took a company making high priced super cars to main stream market of sheep. Junk cars ever since.
Le Mans Master
Joined: Sep 2017
Posts: 5,767
Likes: 2,967
From: Rural NW Georgia. GO DAWGS!
2024 C8 of the Year Finalist - Unmodified
If a case is "defective", i.e. porous, should it leak early in its life or can it happen years down the road? I wonder if GM will extend the warranty beyond 5 years? I will be in the market for a nice used C8 and would like to be confident the tranny won't leak for at least 10 years.
Murphy’s law applied to me. I bought my 09 in November 2019. Four month later I walked out onto my garage and smelled a strong gas odor. I was past the ten year mark and it cost me $1,600 for that repair. It was a $50 part. I’ve seen people on this forum pay close to $3,000 for that repair.
Instructor
Joined: Feb 2021
Posts: 154
Likes: 138
From: Mohave Desert
Tremec
I read somewhere that this trans was bespoke to the new C8 which I took to mean it was designed specifically for the C8. For sure, it is a bummer that folks are having catastrophic failures with some of these, but I have to say, the pics I see of this trans - complete and cut away showing the internals - are impressive. It seems like an engineering wonder to me. I can only hope I get a good one when my car is built on June 29... All the best to those who have theirs in the shop....total F***ing bummer I get it.
Drifting
Joined: Mar 2020
Posts: 1,568
Likes: 1,026
From: 31 hours East of Peoria, AZ
These stats https://www.buyacar.co.uk/cars/autom...automatic-cars are the only ones out there that can be found easily.
The only Chev tranny worth its weight was the TH400 and I had that one after replacing two TH350's. That was on a Suburban. The next Suburban 4x4 also blew its tranny (a 4L60E). Another Blazer also blew it's TH350.
I've stayed away from Chev products now for the last 23 years because of these particular tranny issues. In the meantime, I've had issues with a Lexus RX300 (experimental version) and an MB ML320 tranny.
The stats show that Lexus (Aisin mainly) have a low breakdown rate. I've had 5 Lexii in that last 23 years period with the RX300 as the lemon. The others have been rock solid.
The DCT from from Tremec has had some reports of issues; no big deal with the leaks reported (the tranny still works) but the loss of even / odd gears is the real concerning issue.
The stats shown in the link have a 3.3% problem rate for Chev which is not the worst but way behind the leading group. That is anecdotally by my experience and the stats do not provide a different picture
Your stats?
The only Chev tranny worth its weight was the TH400 and I had that one after replacing two TH350's. That was on a Suburban. The next Suburban 4x4 also blew its tranny (a 4L60E). Another Blazer also blew it's TH350.
I've stayed away from Chev products now for the last 23 years because of these particular tranny issues. In the meantime, I've had issues with a Lexus RX300 (experimental version) and an MB ML320 tranny.
The stats show that Lexus (Aisin mainly) have a low breakdown rate. I've had 5 Lexii in that last 23 years period with the RX300 as the lemon. The others have been rock solid.
The DCT from from Tremec has had some reports of issues; no big deal with the leaks reported (the tranny still works) but the loss of even / odd gears is the real concerning issue.
The stats shown in the link have a 3.3% problem rate for Chev which is not the worst but way behind the leading group. That is anecdotally by my experience and the stats do not provide a different picture
Your stats?
Drifting
Joined: Mar 2020
Posts: 1,568
Likes: 1,026
From: 31 hours East of Peoria, AZ
That was announced in Nov. 2020; Same tranny, different plant.
https://gmauthority.com/blog/2020/11...transmissions/
https://gmauthority.com/blog/2020/11...transmissions/
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Drifting
Joined: Apr 2014
Posts: 1,458
Likes: 625
From: Southeast, FL.
Sooo...just like yours, still leaking and they want to replace the pan. Week and half to get the new pan. Dealership won't push for the new transmission, going to engage with corporate...have little hope of accomplishing anything there. Warranty...wonderful thing, except I am paying for a car I can't use, and odds are the car will be worse off when they are done then coming off the factory floor. The car was delivered in early Jan 2021...wondering if the other 8 problems were from the same time frame?
Dronepilot
Dronepilot
Last edited by OldJedi; Jun 26, 2021 at 11:24 PM.
Racer
Joined: Mar 2014
Posts: 321
Likes: 84
From: Marco Island FL
These stats https://www.buyacar.co.uk/cars/autom...automatic-cars are the only ones out there that can be found easily.
The only Chev tranny worth its weight was the TH400 and I had that one after replacing two TH350's. That was on a Suburban. The next Suburban 4x4 also blew its tranny (a 4L60E). Another Blazer also blew it's TH350.
I've stayed away from Chev products now for the last 23 years because of these particular tranny issues. In the meantime, I've had issues with a Lexus RX300 (experimental version) and an MB ML320 tranny.
The stats show that Lexus (Aisin mainly) have a low breakdown rate. I've had 5 Lexii in that last 23 years period with the RX300 as the lemon. The others have been rock solid.
The DCT from from Tremec has had some reports of issues; no big deal with the leaks reported (the tranny still works) but the loss of even / odd gears is the real concerning issue.
The stats shown in the link have a 3.3% problem rate for Chev which is not the worst but way behind the leading group. That is anecdotally by my experience and the stats do not provide a different picture
Your stats?
The only Chev tranny worth its weight was the TH400 and I had that one after replacing two TH350's. That was on a Suburban. The next Suburban 4x4 also blew its tranny (a 4L60E). Another Blazer also blew it's TH350.
I've stayed away from Chev products now for the last 23 years because of these particular tranny issues. In the meantime, I've had issues with a Lexus RX300 (experimental version) and an MB ML320 tranny.
The stats show that Lexus (Aisin mainly) have a low breakdown rate. I've had 5 Lexii in that last 23 years period with the RX300 as the lemon. The others have been rock solid.
The DCT from from Tremec has had some reports of issues; no big deal with the leaks reported (the tranny still works) but the loss of even / odd gears is the real concerning issue.
The stats shown in the link have a 3.3% problem rate for Chev which is not the worst but way behind the leading group. That is anecdotally by my experience and the stats do not provide a different picture
Your stats?
Racer
Joined: Mar 2014
Posts: 321
Likes: 84
From: Marco Island FL
That was announced in Nov. 2020; Same tranny, different plant.
https://gmauthority.com/blog/2020/11...transmissions/
https://gmauthority.com/blog/2020/11...transmissions/
Drifting
Joined: Mar 2020
Posts: 1,568
Likes: 1,026
From: 31 hours East of Peoria, AZ
Melting Slicks
Joined: May 2021
Posts: 2,562
Likes: 1,579
@Sin City, regarding your suspension and lift errors:
What was it? 170 ECU's?
How many sensors? Probably a lot of glitches or scenarios that might be causing a sensor to read unexpected values.
I got a permanent TCM (transmission control module) code related to a "downshift sensor switch" with a voltage out of reference range. No idea if that means I have an actual problem brewing with my DCT, or if it is just a transient fluke.
You might consider getting a good OBD2 reader. I got the OBDLink MX+, not sure it is the best for this vehicle though. They have no profiles for GM vehicles beyond 2019.
What was it? 170 ECU's?
How many sensors? Probably a lot of glitches or scenarios that might be causing a sensor to read unexpected values.
I got a permanent TCM (transmission control module) code related to a "downshift sensor switch" with a voltage out of reference range. No idea if that means I have an actual problem brewing with my DCT, or if it is just a transient fluke.
You might consider getting a good OBD2 reader. I got the OBDLink MX+, not sure it is the best for this vehicle though. They have no profiles for GM vehicles beyond 2019.
Last edited by dohabandit; Jun 27, 2021 at 10:40 AM.
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
I took museum delivery of my 3LT C 8 on 2/7/2021 after waiting for 15 months. Shifting issues began with "Idle Creep Sensor Disengaged" warning, at 2900 miles, then rough shifts and finally, stuck in second gear. The dealer has diagnosed the problem as a transmission valve body failure. The factory tech team recommended part replacement. The part is expected in 8 days, then we will see what happens. Since no rental or loaner cars are available, GM has offered to reimburse up to $46.00/day for a rental. Currently, rental cars in Orlando are sunning $200.00/day 
Drifting
Joined: Apr 2014
Posts: 1,458
Likes: 625
From: Southeast, FL.
If a case is "defective", i.e. porous, should it leak early in its life or can it happen years down the road? I wonder if GM will extend the warranty beyond 5 years? I will be in the market for a nice used C8 and would like to be confident the tranny won't leak for at least 10 years.
Racer
Joined: Mar 2014
Posts: 321
Likes: 84
From: Marco Island FL
Intermediate
Joined: Jul 2021
Posts: 38
Likes: 5
From: Hinesville, Georgia (Military Retired)
Bad DCT
Thank God after declaring the Georgia Lemon Law and an Attorney, GM finally did a repurchase on my 2020 LT2. The sweet thing is my 2021 LT3 Convertible will be on the assembly line 12 July. Hope I don't have anymore issues with the transmission.
Does anyone know if GM has taken care of the water in the front struts on the 2021s?
Does anyone know if GM has taken care of the water in the front struts on the 2021s?
