Do a search on 8L90 torque converter shudder and you'll get hits across numerous platforms including Silverado, Tahoe, Cadillac, etc.

 

No worries.. Appreciate it.

 

Why do some continue to deny there is an issue with this transmission?

 

I don't know, but the evidence seems very solid to me there is more than one engineering flaw in the tranny's design rather than simply a run of defective parts, at least one that has yet to be effectively addressed by GM. One flaw was/is delayed engagement addressed by the stator shaft support, o-ring, and check valve repair (#16-NA-14). There's a question as to whether that one has been effectively addressed, but the V4 shuddering (PIP5337E) clearly has not. The new TC part number surfaced around 11/01/15, which suggests that all cars built after that time should have it, but we see 2016 and even 2017 cars with the same problem. Furthermore, cars that have been repaired with the revised part are coming back with the same issues after a short period of time.

If this isn't clear, what evidence do we need for it to be clear? We surely aren't going to get a lucid explanation from GM with pertinent facts and figures, so what we see here and in other forums is about all we have to go on.

For me the answer is to bail from the A8 experience altogether. Since I've had a Corvette in my garage every day since 1980 and believe the C7 is an engineering work of art, my solution is to move to an M7, which unlike most is an option I actually prefer.

 

Possibly because the majority of A8 owners are not having issues and are impressed with the way the A8 performs.

 

I am so angry with my dealer and GM that I can't even contemplate buying another Vette right now. This was my first and what a disappointment it was. The A8 issues were bad enough, but the dealer response was enough to sour me on the brand for a long time.

 

Perhaps, but since I am one of the unlucky whose car was disassembled and out of service for more than 30 days I am convinced that there are issues with the A8. How prevalent, I don't know. I just hope the repair holds. The car is running great now.

 

10/14 build date. Replaced the TC at 15K. Still having issues with shift 1 to 2. Will get back to dealer when weather is some better. 2015 Z-51 Vertt.

 

My Dec 2014 built A8 was perfect until the 5,000 mile mark. Then the torq converter shudder showed up. The converter was replaced about 400 miles ago. So far so good. Also, the dealer did an excellent job doing the replacement. Mine was the 2nd that they replaced.

 

I know how you feel. The way dealers handle (or fail to handle) problems is really more impactful to me than the problem itself. I have bailed on two brands just because of the way I was treated. The problems were fixable, but just was so furious about the way the local dealers treated me.

That's my take too, after spending time looking thru the failure rates. Hey, I'm an engineer and it's -10 here in MN . . . nothing else to do! I found about an equal number of failures under 10K as over. My take would be more of a QC cause, especially those after the 2015 design update. Not that this excuses anything, just interested.

Also somewhat optimistic of the late 2015 design update since, of the 2016 failures, 3 were built in 2015 before the TC update.

Anyway, I know for a fact that my A8 will be fine for the next 3 months-- It's hibernating.

 

Great picture! Love it.

 

And maybe you should consider that by your standards, a 49% failure rate is a good job since the majority is OK.

It doesn't have to be a QC problem. QC could be insuring things are within specs but a combination of parts, all within spec, create a failure scenario. Meaning that the specs aren't tight enough. We just don't have enough information to know.

 

Ironically, I've had 2 A8 C7's w/o issue. Both high milage vehicles. A '15 MY Z51 and a mid year built '16 Stingray. However, the MY'16 build Z06 is now in the shop because of noise from the rear end of the car. Waiting for its turn to be looked at. I am keeping my fingers crossed with the new CTS V. I did at least purchase what Cadillac calls a vehicle wrap extended coverage package.

 

Regarding the V4 shuddering (PIP5337E), what happens if you disable V4 and continue to drive. Will the TC ever really have a problem? Some owners have disabled V4 from day one so they would never experience this problem.

 

While that's an interesting question, if the TC is malfunctioning in V4 mode, there's something wrong with it, which will ultimately show up in V8 mode. There's nothing inherent in V4 mode that should affect TC function if the transmission is functioning properly.

 

Its human nature to a) rationalize that you made a good decision and b) its not going to happen to me, and c) there is the "Fanboy Factor"

Its clear there is a problem and that on the order of 10% have been replaced within the first 10K miles, I think the big question is what happens by 50K miles? Does it remain at 10% range or does it become say 50%?

 

Understood, but that doesn't answer my question. Well, I guess you sort of answered it, but it doesn't sound like you know from actual experience. Maybe someone else can answer it, but it may be too technical for anyone to really know.

Let me ask a different way.
1) If I have the V4 shudder issue and I disable V4, will the TC exhibit other problems and need to be replaced prematurely?
2) Could continued operation with the supposed faulty TC with V4 disabled cause other transmission problems such as premature wear of clutches?

 

Interesting questions! I have never quite understood the V4 shudder and TC interaction.

 

You're right I don't have direct experience on the C7, but I do understand well how transmissions deliver power from engine to the drive wheels. I can't see how there could be anything different about that in V4 mode, except less torque being delivered to the trannie. The same lower torque levels would be delivered at lower V8 rpms.

I suppose it could be software-related in that mode, but mechanically it shouldn't matter. If it were software-related why are they just replacing TCs?

 

But that is not reality, is it? Look at the poll and you have a grand total of 2 failures for 2016 and 2 failures for 2017. Yes, we all know very well that a poll like this is "not accurate!" for a variety of reasons that everyone points out in every poll conducted, but in the general sense of what this poll shows, you can't claim a 49% failure rate. What you see is a clear downward curve in the rate of failure with the VAST MAJORITY reporting no problems. In addition, people who have failures are compelled to tell us all about it where people who do not have failures remain silent. I have nearly 22,000 trouble-free miles on my A8, but that matters not to someone who has had a failure. That leads to a skewed sense of the failure rate. If you read this forum you would think A8 failures are quite common when the data show it's not common at all. I don't blame anyone who vents about their issue. It just needs to be taken in context. If your interpretation of the data leads you to avoid the A8, buy a manual. If you don't want a manual, choose another car. My interpretation of the data we have is that whatever they did for 2016 has substantially reduced the problems. What is really strange to me is people getting on here and saying they'll never buy another corvette. OK. Fine. No problem. But if you can't stick it out, please go away.