2016 Z51 Coupe with A8
Build date October 2015 and brought it home 10-22-15.
Just turned 6500 miles yesterday and no problem so far.

 

Couldn't agree more. It has to be a quality of build issue on the converters or something because there are guys out there with some serious horsepower beating these things up with the factory torque converter and transmission. One guy I know of has over 20 thousand miles on the original converter and transmission with an F1R Procharger that beats the heck out of the car and participates in various speed events. In contrast though, Some like we have seen on this thread recently are getting their 2 week old car's torque converter replaced. Seems like the design could be robust, GM just has to figure out what the heck the problem is in the build. Will be curious to find out, if we ever do. I know I will continue to beat up on mine as often as I can.

 

Just sent you a p/m. Mike

 

That's exactly what would worry me so much about this situation. One failure I could stomach, but what's to keep the replacement from failing, since they are still failing in new cars?

Regardless of whether the failure rate in this poll is accurate or not, even 5% is indicative of a very big problem when it's the same system failing. Even a 5% warranty return rate for all systems combined would be a cause for concern for most car manufacturers.

 

If I am reading this poll correctly 24 of 90 model 2015's have had torque converter or transmission failure. Considering the low mileage on some vehicles there could be a huge percentage at 60,000 miles.

 

I've asked this before, but : Do Corvettes have torque converters or torque tubes?

 

The poll numbers add up to more than 100% because some have owned more than one C7 and voted multiple times. Some votes are also of questionable validity.

However, the current poll reported failure rate for all model years is at 17.49%, and even if it were half that, it would be a huge number considering that probably no C7 in the sample is close to 60K miles.

Automatic C7s have both. Similarly, manual C7s have both a clutch and and a torque tube.

 

Both, Tube is like a drive shaft.

 

I don't necessarily think that more mileage means more failures. We are seeing some in the 20K mile range with no issues. I think if you've made it to a certain point, the failures causing what is happening now will not rear it head hopefully. Not to say that new issues will not arise.

 

Can anyone show a diagram (probably exploded) that shows both? I thought it only had the torque tube.

Anyway, which (if applicable) is the actual problem child?

With clear labels, please.

 

Well, that's a positive way of looking at it. Hope you're right.

Correct. The torque tube has the drive shaft inside, and is also a major structural component of the chassis.

Here's a picture, but I don't feel like going in and adding labels at this late hour.

The trannies of both auto and manual are located in the rear for weight balance reasons as they were in the C6. The automatic transmission torque converter is inside the transmission case. The torque tube connects the engine to the transmission, and it's clear in the picture what that is.

The torque converter is the main "problem child," and I've heard of no torque tube replacements in all these discussions about A8 problems. If torque tubes were issues, we'd be hearing of replacements in M7s too.

 

What bothers me is that we are still seeing an issue with low fluid levels in the diff. Why in the hell isn't it a part of the dealer PDI to check it ? Or, before the component is installed at BG.

 

^^^ I can tell you why. It is an indication of poor quality control when a significant component or fluid is not installed to proper specifications. Especially fluid levels when it is a comparatively simple system to check. Obviously the person responsible for filling the fluid to proper level did incorrectly and the QC department failed to check the level. I can't imagine that fluid levels are not on a QC check list.

 

The differential is filled by the supplier with extremely tight parameters. Mass flow sensors control the amount of fluid in each and every fill to exact specifications. The same kind of processes are used in the Performance Build Center. I have seen these processes and they are incredibly precise. All of these components are traceable as to the exact amount of fluid that was filled in each component when there is a warranty claim.

The bigger issue has to do with how everyone tests to see if they have enough differential fluid or not. Mass to volume is what is important in these cases. A properly filled differential is not necessarily one that allows a little to seep from the fill hole when you are filling it up, though some service departments would say it's full based on this. There can also be residual fluid in the various differentials that was not drained, and a "full" differential could wind up being an overfilled differential. I think the bigger issue has to do with various service departments and how they check, evaluate, and fill our Corvette differentials. I know in other matters with our Corvettes, the level of knowledge and expertise is all over the chart depending on the dealership.

 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

That sounds like a good explanation, perhaps.

However , there have been forum members starting with the 2014 MY that have posted here they had " service rear axle " DIC messages and if I remember correctly they posted that the result was the service department had to add fluid as it was found to be low ???

 

Jeremy, I absolutely agree with you. The lack of knowledge at some Chevrolet/GM dealers about the C7 has been well documented on this forum. I maintain that GM restrict the sale and servicing of Corvettes to only those dealers that can demonstrate competence on a recurring basis. At this point in time it is a crapshoot when you take your can in for service.

 

There was a problem w/ differential fluid being under-filled early in the 2014 MY, for both manual and automatic. GM quickly sent out a bulletin to customers directing them to return them to the dealerships for a check. That problem hasn't recurred since.

Diff fluid level has nothing to do w/ the A8 issues.

 

Based on the TSBs issued by GM on the A8 tranny, the issue is supposed to be one or more of these:

Lack of O ring
Defective TC (may be related to the O ring)
Defective stator support

There could be other issues as well that GM has not addressed yet.

I am curious to understand the nature of the issues being experienced by owners of cars other than the Corvette that use the same transmission but in a different installation in the vehicle.

 

^^^It's the same in the Silverado. Delayed engagement, rough shifts, and shuddering.

 

No, unfortunately the software does not allow this.