[unodonjuan]

I wanted to ask our Corvette Community about the C8 2022 transmission issues. On FB Corvette blog people are writing about transmission replacement because of break down with less than 5000 miles. Some have posted changing transmission fluid at 2000 miles? Is this seen more on Z51 vs Non Z51? I am at 3000 miles on my 2022 non Z51 and have had no issue (BTW.. my 7th Vette and have never had major issues).Would appreciate honest feedback for clarification.
Thank you
Uno

 

[meyerweb]

There have been some DCT issues. More than GM would like, to be sure. But consider that there have been some 50,000 to 60,000 C8s produced and sold. If even 10% of those had transmission issues, the Corvette forums would be inundated with nothing but faulty DCT posts. Most owners don't seem to have any problems with the DCT.

In the early production DCTs, there were problems with porous castings in a part called the valve body that caused leaks in some cases. That was resolved. There have been gasket leaks where the pan on the bottom of the DCT attaches to the DCT case. The unit was redesigned with a cast pan that seals with an o-ring rather than a gasket. But both of those issues seemed to affect only a relatively small number of units.

There have been [unproven] reports that some problems have been caused because a supplier of components to Tremec wasn't properly cleaning the parts, and debris was getting into the DCT. While unconfirmed, the fact that GM has added a "flush" procedure to the DCT filter change (the procedure forces the DCT fluid to circulate through the filter for 8 minutes prior to the filter being changed. It's not a traditional flush and refill), and asked dealers to ship used filters back to them for study seems to support this.

But the important part is that the vast majority of owners don't seem to have these problems.

And there's no difference in the DCT between the Z51 and base. The transfer gears between the engine and transmission are different, and the Z51 has an electronic limited slip differential, but the DCT itself is identical: same clutches, same gears, same valve body, same everything.

I'm at 6400 miles on my 2021, and the DCT is fine.

 

[unodonjuan]

There have been some DCT issues. More than GM would like, to be sure. But consider that there have been some 50,000 to 60,000 C8s produced and sold. If even 10% of those had transmission issues, the Corvette forums would be inundated with nothing but faulty DCT posts. Most owners don't seem to have any problems with the DCT.

In the early production DCTs, there were problems with porous castings in a part called the valve body that caused leaks in some cases. That was resolved. There have been gasket leaks where the pan on the bottom of the DCT attaches to the DCT case. The unit was redesigned with a cast pan that seals with an o-ring rather than a gasket. But both of those issues seemed to affect only a relatively small number of units.

There have been [unproven] reports that some problems have been caused because a supplier of components to Tremec wasn't properly cleaning the parts, and debris was getting into the DCT. While unconfirmed, the fact that GM has added a "flush" procedure to the DCT filter change (the procedure forces the DCT fluid to circulate through the filter for 8 minutes prior to the filter being changed. It's not a traditional flush and refill), and asked dealers to ship used filters back to them for study seems to support this.

But the important part is that the vast majority of owners don't seem to have these problems.

And there's no difference in the DCT between the Z51 and base. The transfer gears between the engine and transmission are different, and the Z51 has an electronic limited slip differential, but the DCT itself is identical: same clutches, same gears, same valve body, same everything.

I'm at 6400 miles on my 2021, and the DCT is fine.

Thank you for your thorough explanation. Last question. Should I wait to recommended 7500 miles or sooner?
Thank you
Juan

 

[DurkinsRay]

I have a ‘21 with 24,000 miles. Just had the trans fluid changed which they recommend at 24,000 miles. Have not had any issues (knocking wood) thus far. Use paddles exclusively on my base C8.

 

[unodonjuan]

I have a ‘21 with 24,000 miles. Just had the trans fluid changed which they recommend at 24,000 miles. Have not had any issues (knocking wood) thus far. Use paddles exclusively on my base C8.

I have a 2022 C8 Coup non Z-51 with 3k miles and no problem. The Corvette Mechanic at the dealership where I had bought 6 Vettes before he has not seen issues with the transmissions on C8’s👌

 

[Fleet]

Somewhat repetitive but ..... After picking up my C8 at museum the car's "Check Engine Light" came on with 450 initial miles. Car drove and acted normally and I continued my trip home. By the time I got to the dealer the trouble light was out and the only code found was a transmission error. The dealer recommended I do the 7500 mile service (Includes engine oil and tranny filter change) with 1186 miles on the car. I don't believe there was a problem since the car was performing perfectly but I agreed to the an early first service interval as insurance. The car just turned 3000 miles and the transmission is still working flawlessly.

 

[Vette Interested]

Go my car last December. So far 3,400 miles and no transmission Issues. Hopefully that remains the case.

 

[meyerweb]

Thank you for your thorough explanation. Last question. Should I wait to recommended 7500 miles or sooner?
Thank you
Juan

Unless you're having an issue, I don't think there's a reason to change the filter much earlier than 7500. I had mine changed at ~ 6400 because I was getting ready for a 2,000 mile trip and didn't want to wait until I got back.

In fact, at Carlisle last year, a couple of GM's engineers from the DCT program gave a presentation, and said in response to a question that if you change it extremely early (I think the question was about changing it at ~ 2000 miles) they'd recommend doing it again at 7500 because the transmission gears and clutches will continue to break-in during that time.

The dealer recommended I do the 7500 mile service (Includes engine oil and tranny filter change) with 1186 miles on the car.

See comments above about the Carlisle presentation.

 

[unodonjuan]

Unless you're having an issue, I don't think there's a reason to change the filter much earlier than 7500. I had mine changed at ~ 6400 because I was getting ready for a 2,000 mile trip and didn't want to wait until I got back.

In fact, at Carlisle last year, a couple of GM's engineers from the DCT program gave a presentation, and said in response to a question that if you change it extremely early (I think the question was about changing it at ~ 2000 miles) they'd recommend doing it again at 7500 because the transmission gears and clutches will continue to break-in during that time.



See comments above about the Carlisle presentation.

Thank you. The mechanic at the Chevy dealership said the same thing.

 

[Jerry U]

Someone recently posted that at the Bash they were told by a GM Rep at a maintenance lecture to change the DCT filter at the 1st engine oil change. That matched my logic August 2021 when my OLM say 5% life left with 3500 miles. My logic included:

1. A filter change requires a DCT flush
2. My 1st gear clutch was a bit jerky below ~4 mph when I crawled into my garage controlling the mirror tip to wood door molding to 1 to 3 inches so passenger mirror (harder to see) was sure to clear. After ~500 to 800 miles as now it's perfectly smooth. As expected the 1st gear (3rd, 5th, 7th) is slipping until about 5 mph AND when stopped at a stop sign, red light etc. Expected initial wear as the plates wore in.
3. A number of owner's have posted getting DCT CELS and GM told dealer to perform a flush
4. You are required to change all 11 quarts of DCT fluid at 3 years (Note 4 in Maintenance Table.) So waiting until year 2 is IMO a waste as my plan year 3 is to replace the DCT filter again (on my dime.) Seems foolish to replace the fluid and leave some dirty old fluid and filter in trans. Will have ~7000 miles on my changed filter.

Pic of Dealer Tech's PC performing DCT flush BEFORE my DCT Filter change. It's REQUIRED per the GM filter change procedure. Takes About 10 minutes as we watched since GM Service Computer connected via WiFi sent signals to running C8 that opens solenoids, moves shift forks or whatever. At end it says FLUSH COMPLETED! Procedure said that causes any debris to move into filter housing prior to changing filter.