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Does anyone know why the C8 DCT can fail? Are there common failure points? Although I see several reports of failures/replacements on the forums, I see far less information on what actually goes bad. Is it a clutch pack, a module, something else physically in the box? etc.
When a transmission is replaced, there is little info on what was wrong with it. But there have issues that were repaired. One was a an issue with the "direct clutch and stator". Several have been fixed with a valve body replacement. There were case porosity issues - early on I think. I believe those required replacement. There may have been pan gasket leaks - the pan design was upgraded. I think I recall on case where the seal around the harness that goes into the transmission leaked and that was fixed. Some are fixed with one or more Transmission Service Cleaning Procedures or a Hydraulic System Flush (those are scan tool initiated procedures that do something internal with a goal of moving debris to the filter). So those were probably debris related.
@RKCRLR listed some examples as well recently in another thread. Perhaps he can chime in here.
That's interesting. I hope that with more time and as more C8's come out of warranty, we start to see people figuring out the sources of failure and hopefully some aftermarket vendors come up with fixes/preventative maintenance etc.
Mine has had both the pan and pan gasket as well as the passenger side axle cover seal replaced due to leak issues. 2023 under 8k miles mostly track use.
When a transmission is replaced, there is little info on what was wrong with it. But there have issues that were repaired. One was a an issue with the "direct clutch and stator". Several have been fixed with a valve body replacement. There were case porosity issues - early on I think. I believe those required replacement. There may have been pan gasket leaks - the pan design was upgraded. I think I recall on case where the seal around the harness that goes into the transmission leaked and that was fixed. Some are fixed with one or more Transmission Service Cleaning Procedures or a Hydraulic System Flush (those are scan tool initiated procedures that do something internal with a goal of moving debris to the filter). So those were probably debris related.
@RKCRLR listed some examples as well recently in another thread. Perhaps he can chime in here.
Many of them have been covered here. There is also the Park sensor failure and fastener torque recall that require replacement of the DCT. And some software updates that fix the problems.
The point is that the DCT is complex and the more components the more likely a component is going to fail, and all it takes is one. There isn't a single cause of the problems. The same problem could have different symptoms depending on the conditions when it was detected. And different problems can cause the same symptoms when the computer takes over. There are so many sensors that it could be nothing more than a sensor failing in some cases and that there is actually nothing else wrong.
I believe there will eventually be places that can overhaul and fix these DCTs but it will probably require a lot of specialized tooling. It will be beyond the scope of a typical dealer or repair shop.
Many of them have been covered here. There is also the Park sensor failure and fastener torque recall that require replacement of the DCT. And some software updates that fix the problems.
The point is that the DCT is complex and the more components the more likely a component is going to fail, and all it takes is one. There isn't a single cause of the problems. The same problem could have different symptoms depending on the conditions when it was detected. And different problems can cause the same symptoms when the computer takes over. There are so many sensors that it could be nothing more than a sensor failing in some cases and that there is actually nothing else wrong.
I believe there will eventually be places that can overhaul and fix these DCTs but it will probably require a lot of specialized tooling. It will be beyond the scope of a typical dealer or repair shop.
Dont most modern automatic transmissions require a lot of special tools, jigs, etc. They look pretty complex to me. I've torn down engines (older simpler ones) and tranmissions (tractor transmissions). But I doubt I could do that successfully with a modern manual or automatic. In many ways, to me, the slush box automatics seem much more difficult to understand that the C8 DCT.
I wonder what they do with all the transmissions they replaced besides dissecting them to see what the exact failure was? Im surprised they don't fix and rebuild them to replenish stock at the dealers so we dont have to wait so long to replace.
I wonder what they do with all the transmissions they replaced besides dissecting them to see what the exact failure was? Im surprised they don't fix and rebuild them to replenish stock at the dealers so we dont have to wait so long to replace.
I suspect we will see remanufactured C8 DCTs in the future.
Does anyone know why the C8 DCT can fail? Are there common failure points? Although I see several reports of failures/replacements on the forums, I see far less information on what actually goes bad. Is it a clutch pack, a module, something else physically in the box? etc.
See no one posted the Video I think is great by a tech who investigated ~50 with CELs:
As he notes there are very many sensors to protect the DCT. Over 100 CEL Codes. Seldom sees the same code. Really not that complex! Two 4 speeds with shift folks, Synchros for each gear. etc. The basic difference from a standard shift is many solenoids and hydraulic actuators that move the Forks NOT a Lever. Failures could be a simple as a failed solenoid.
What does Tremec do with the failed units?
As a vendor you can be sure they get them as IMO they probably have to replace free during warranty (it's their transmission they have to stand by it!)
Do they just through throw in Lake Michigan as fish habituate? Nope they probably fix whatever and give as a reconditioned replacement if few miles. Have the same warranty as a new unit they must standby.
When warranty expires transmission shops will be able to repair. They repair other DCTs.
I wonder what they do with all the transmissions they replaced besides dissecting them to see what the exact failure was? Im surprised they don't fix and rebuild them to replenish stock at the dealers so we dont have to wait so long to replace.
They have a transmission shop in Michigan where they were initially assembled for ~3 years until GM took over in Canada. They suppply other transmissions for cars, trucks, off road equipment. My guess is their supply contract requires free replacement during warranty or 3/4 year minimum. Can be sure they are not tossed into Lake Michigan as fish habituate! What would you do IF you found only one solenoid was bad in a trans with <500 miles??
My guess is they are provided as replacements with a new trans warranty. Just a Guess!
As he notes there are very many sensors to protect the DCT. Over 100 CEL Codes. Seldom sees the same code. Really not that complex! Two 4 speeds with shift folks, Synchros for each gear. etc. The basic difference from a standard shift is many solenoids and hydraulic actuators that move the Forks NOT a Lever. Failures could be a simple as a failed solenoid.
What does Tremec do with the failed units?
As a vendor you can be sure they get them as IMO they probably have to replace free during warranty (it's their transmission they have to stand by it!)
Do they just through throw in Lake Michigan as fish habituate? Nope they probably fix whatever and give as a reconditioned replacement if few miles. Have the same warranty as a new unit they must standby.
When warranty expires transmission shops will be able to repair. They repair other DCTs.
DCT Failures - Any Tech info/analysis?
