A8 Automatic issues wide spread or not?

ta-kid

ta-kid

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So I am looking to purchase a C7 corvette and most that are in the colours and options I like, are running A8 transmissions.I have always had Standard ZO6 cars but thinking of switching to Auto but concerned over some of the issues I have heard about.Are they wide spread over all years or is it just a small percentage?Who is running an A8 as a daily driver for a couple years who can chime in and make me feel warm and fuzzy about buying an Auto Vette.I have test drove one and they do shift nice and crisp but.
I have read about doing a triple flush {I assume to get all the old oil out of the TC}with the new mobile tranny fluid which appears to fix the problem.
 
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ta-kid said:
So I am looking to purchase a C7 corvette and most that are in the colours and options I like, are running A8 transmissions.I have always had Standard ZO6 cars but thinking of switching to Auto but concerned over some of the issues I have heard about.Are they wide spread over all years or is it just a small percentage?Who is running an A8 as a daily driver for a couple years who can chime in and make me feel warm and fuzzy about buying an Auto Vette.I have test drove one and they do shift nice and crisp but.
Click to expand...
I have a 2015 and based on discussion with my dealer it's pretty wide spread. The first couple of years I had put so low kms on I never noticed it but once I went from adding only 3000kms to 7000kms and doing some track stuff that I started noticing issues. The good news is that it's fixable, those with the shudder while driving was fixed with the new trans oil triple flushed. My issue was significant jerk when going from park to drive and I was still on warranty so in 2018 I asked if I can get a brand new transmission and differential and it was approved. Since then no issues at all. My recommendation is get a c7 with at least 25000kms on it and ask if the prior owner did any of these fixes. If not make sure you drive it to get it nice and hot because the hotter the transmission gets the issues jump out at you. Don't be afraid of the A8 just ask the right questions and test drive just like any other car.
 
From what I have heard , you might have been lucky to get a new transmission , as apparently the few class action suits regarding this problem have been rolled into one class action . Apparently GMs position is they are not responsible as this is a design problem and not a quality problem and their warranty covers quality problems not design problems on the products they sell. 😏
I’m not sure of their position on all the bent and cracked wheels !
If we can focus our attention on all the hype about the new flawless C8 and what a great job they have done , I’m sure these C7 problems will soon disappear!
 
ta-kid said:
So I am looking to purchase a C7 corvette and most that are in the colours and options I like, are running A8 transmissions.I have always had Standard ZO6 cars but thinking of switching to Auto but concerned over some of the issues I have heard about.Are they wide spread over all years or is it just a small percentage?Who is running an A8 as a daily driver for a couple years who can chime in and make me feel warm and fuzzy about buying an Auto Vette.I have test drove one and they do shift nice and crisp but.
I have read about doing a triple flush {I assume to get all the old oil out of the TC}with the new mobile tranny fluid which appears to fix the problem.
Click to expand...
Okay, I'll take a shot at giving you a direct answer to your question. First off, because the "shudder" is not deemed to be a recall, there is no published statistical data that would show the true rate of failure. Anecdotally, the perceived failure rate is believed to be between 2 and 5 percent with the majority of affected C7's coming from the 2015 and 2016 model years. There have been a number of component modifications and improvements, valve modulator bodies, torque converters and ATF's, since the 2016 MY that have helped to improve the problem. Any vehicle produced after February, 2019 has the latest ATF and the most up to date transmission components.

Just a few points of clarification on this issue. First off, the torque converter "shudder", as related to the 8L90 8 speed automatic transmission, is caused by the operation of the Active Fuel Management System (AFM). The problem occurs because the lock-up clutch in the torque converter fails to lock completely during the change from V8 to V4 mode. This is now thought to be due to excessive moisture absorption by the ATF within the transmission, or so says the latest from GM. They have gone through 3 different formulations of Mobil 1 Synthetic ATF with the third, and so far final version, being the most successful. The general consensus is that the latest triple flush approach with the newest ATF (see attached TSB) will, in most cases, solve the problem.

I have put 15,000 trouble free KM's in almost 3 years on my 2019 GS with the A8 transmission, although that may not be sufficient mileage in order for the problem to appear. Many owners do not experience the "shudder" until 30 to 50 thousand KM's or more. But consider that more than 95% of C7 owners, with A8's, have never experienced the problem and probably never will. Did GM drop the ball in terms of customer support with this problem? Yes. They, in my opinion, should have recalled all vehicles with the 8L90 transmission and fixed the problem, once they had an effective resolution, but that's not happening. Can the problem be corrected? Yes, for the most part, with the latest triple flush that will be performed free of charge under GM's 5 year / 100,000 kl powertrain warranty. Would all of this stop me from buying a C7 with the A8 transmission? Not a chance, love the manual mode of this transmission with it's quick, precise shifts ( in Sport / Track mode ) and the ease of use as an automatic, for the wife of course. :)

Hope this helps.

Best regards
Ross
 

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Curious what I should budget for the triple flush at a dealership?
... should anyone happen to know and will share ...

... just so in the event it is too inconvenient if/when asking a friend to help out
as I am not one would cannot take advantage a friend's time and effort without
something in return.

So far I have fortune without Corvette A8 issues popping up
over the initial 5 years and at just over 20k ...
my other at 4 years with less than 10k.
Taking a Boy Scout approach for now
but might consider "an ounce of prevention" instead.
 
Last edited by a moderator:
SN3-waldo said:
Curious what I should budget for the triple flush at a dealership?
... should anyone happen to know and will share ...

... just so in the event it is too inconvenient if/when asking a friend to help out
as I am not one would cannot take advantage a friend's time and effort without
something in return.

So far I have fortune without A8 issues popping up
over the initial 5 years and at just over 20k ...
my other at 4 years with less than 10k.
Taking a Boy Scout approach for now
but might consider "an ounce of prevention" instead.
Click to expand...
Although the triple flush can be done as a DIY service, it's a difficult job at best. Without the factory lines, couplers and flush machine it's almost impossible to get all of the old ATF completely out of the system and that is critical to fixing the TC "shudder". As much as it pains me to say it, you're better off to have it done at a COMPETENT dealership. I know, that's a tall order but there are some and if you can find one that will do the job properly it's probably worth the cost. I say "properly" because I am personally aware of a dealer who skipped running the transmission through all 8 gears plus reverse and neutral in between flushes. They claimed that it wasn't necessary as the complete fluid exchange is effected without performing this step. They obviously know better than the GM / Mobil 1 engineering staff. Typical dealer BS and, needless to say, my friend's TC "shudder" came back in about 5000 kls. The dealer was just trying to save time and, as such, make more money on the warranty repair.

It's unfortunate for those who's car is no longer covered under the powertrain warranty as the out of pocket repair is quite expensive. Pricing will vary depending on region and if you're buying the ATF from the dealer, from an e-seller or an independent supplier. Average online price for Mobile 1 Synthetic LV ATF HP blue label is around $110.00 CDN for a case of 6. You'll need 24 qts. / ltrs. Don't know what dealers are selling it for but I would think it's a lot more. Add approximately 3 hours of labour @ $120.00 per hour, again, depends where you are, and the lowest price you're likely to see is around 800.00 CDN.

Another option is to try a friction modifier like Lubegard. This would be considered an "ounce of prevention" and is, in my opinion, a DIY service. If you do the research, particularly on the large US forums, you'll find that a number of C7 owners have had some success with this approach. This will be my first shot at fixing the "shudder" if / when it occurs.

Best regards
Ross
 
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Rruuff Day said:
Flawless? Not counting the several fairly minor flaws noted to date, let's give them the same time span the C7 has been on the road to see if "flawless" still applies....JMO
Click to expand...
Flawless mmmm I doubt !! But might GM step up and fix problems or call them design flaws and not their responsibility ??
 
cdnrx1 said:
Okay, I'll take a shot at giving you a direct answer to your question. First off, because the "shudder" is not deemed to be a recall, there is no published statistical data that would show the true rate of failure. Anecdotally, the perceived failure rate is believed to be between 2 and 5 percent with the majority of affected C7's coming from the 2015 and 2016 model years. There have been a number of component modifications and improvements, valve modulator bodies, torque converters and ATF's, since the 2016 MY that have helped to improve the problem. Any vehicle produced after February, 2019 has the latest ATF and the most up to date transmission components.

Just a few points of clarification on this issue. First off, the torque converter "shudder", as related to the 8L90 8 speed automatic transmission, is caused by the operation of the Active Fuel Management System (AFM). The problem occurs because the lock-up clutch in the torque converter fails to lock completely during the change from V8 to V4 mode. This is now thought to be due to excessive moisture absorption by the ATF within the transmission, or so says the latest from GM. They have gone through 3 different formulations of Mobil 1 Synthetic ATF with the third, and so far final version, being the most successful. The general consensus is that the latest triple flush approach with the newest ATF (see attached TSB) will, in most cases, solve the problem.

I have put 15,000 trouble free KM's in almost 3 years on my 2019 GS with the A8 transmission, although that may not be sufficient mileage in order for the problem to appear. Many owners do not experience the "shudder" until 30 to 50 thousand KM's or more. But consider that more than 95% of C7 owners, with A8's, have never experienced the problem and probably never will. Did GM drop the ball in terms of customer support with this problem? Yes. They, in my opinion, should have recalled all vehicles with the 8L90 transmission and fixed the problem, once they had an effective resolution, but that's not happening. Can the problem be corrected? Yes, for the most part, with the latest triple flush that will be performed free of charge under GM's 5 year / 100,000 kl powertrain warranty. Would all of this stop me from buying a C7 with the A8 transmission? Not a chance, love the manual mode of this transmission with it's quick, precise shifts ( in Sport / Track mode ) and the ease of use as an automatic, for the wife of course. :)

Hope this helps.

Best regards
Ross
Click to expand...
Thanks for the great information 👍👍👍
 
Corman said:
Glad I chose a manual transmission.
Click to expand...
For a different reason, aren't we all.... :Biggrin:

1612136260767.png
 
Just facing ‘The Shudder’ in my 2015 Stingray that has just shy of 20,000 Kms. It was find when I parked it for the winter. I suspect the heated garage may have contributed to the moisture issue with the original oil. It’s going in the shop next Friday and I suspect they will come back suggesting the triple flush. Another local dealer quoted me just shy of $1200 as an all in price. I will circle back here with the cost and resolution when I have one. Sure hope it’s just that or it may be going for sale or trade on something else!
 
Racer66 said:
Just facing ‘The Shudder’ in my 2015 Stingray that has just shy of 20,000 Kms. It was find when I parked it for the winter. I suspect the heated garage may have contributed to the moisture issue with the original oil. It’s going in the shop next Friday and I suspect they will come back suggesting the triple flush. Another local dealer quoted me just shy of $1200 as an all in price. I will circle back here with the cost and resolution when I have one. Sure hope it’s just that or it may be going for sale or trade on something else!
Click to expand...

Looking forward to hearing what the dealer(s) suggest for you, hopefully it doesn't end in you having to sell/trade the vette.

If this issue ever pops up for me, I'm doing it myself, I just cannot fathom paying that price for this job.

Good luck OP
 
I agree the price is crazy but since 80% of the cost is the ATF I would hate to do it myself and leave some old hydroscopic oil in there and have the issue come back. Fingers crossed that I get it fixed and none of you ever face this gremlin!!!
 
Hi Racer:

Genuinely sorry to hear that your C7 has developed the "shudder". However, if it is experiencing early signs that may, in some ways, be a bit of good news. Given that the 2015 MY was the first to be fitted with the 8L90 transmission, they were subject to a number of teething problems. They included delayed engagement when shifting into drive and/or reverse when cold and harsh up/down shifting. Both problems were fixed with an improved modulator valve. There was also damage to the torque converter lock-up clutch which was caused by continued use while experiencing the "shudder". This necessitated the replacement of the torque converter with an updated part. As your car has just started to exhibit early signs of the "shudder" it's likely that the triple flush procedure with the new Mobil 1 Synthetic LV ATF HP Blue Label fluid may solve the problem.

Two things that you might try. 1) Contact GM Canada, or have your dealer do it, explain the problem and quote the attached TSB. It's a well known failure with the 8L90 transmission and it's worth asking GM for some good will. 2) See if your dealer will allow you to provide the ATF. It can be purchased from Amazon, Napa or Mobil distributors for much less than the dealer's price.

Finally, I would not recommend trying the triple flush as a DIY project. Without the flush machine, the quick connect hoses and couplers you will never get all of the old fluid out of the transmission. Even small amounts left can result in the return of the "shudder".

Best of luck.

Ross
 

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