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Latest on A8 Shudder problems

 
Old 01-07-2019, 08:31 PM
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Gearhead Jim
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Default Latest on A8 Shudder problems

Today I was speaking with the Corvette tech at our local dealer, he's a very sharp guy who owns a C6 and works on a lot of C7's because of his reputation.

He's been told recently by people in GM that they are coming out with yet another transmission fluid designed to fix the A8 shudder problem. According to what he was told:
The new fluid will be from Mobil, in bottles that looks similar to the one currently recommended, but with a different part number.
Initial deliveries of the fluid will be to dealers and areas that are having the most A8 problems, but he doesn't know who or where they are. Exact timetable is unknown.
The basic procedure will remain to do a drain and refill with the new stuff, if problem recurs then do another drain and refill. There may be more.
GM seems hopeful that this will be the "final solution" to the A8 shudder problem. Yes, we've heard that before.
He speculates that if a second drain/refill with the new stuff doesn't solve the problem, then GM may authorize a new TC or tranny, but that's just his personal guess.
The most recent bulletin about this is #16-NA-175, dated October 11 2018, before this "latest and greatest" fluid. That bulletin will updated with the new fluid and procedure.

It will be interesting to see how this fits with the recently filed class action lawsuit against GM regarding A8 problems, discussed in another thread here.

There is a old bulletin #16-NA-355 that is about remote start kits and has nothing to do with A8 problems.
When I find a copy of 18-NA-355, I'll post a link unless someone beats me to it.

Usually I refrain from posting unverified information, but this guy usually knows what he's talking about. Of course, his information is only as good as what he gets from GM.
He says he can't recall replacing any A8 converters or trannys on Corvettes because of the shudder problem, the fluid changes and/or updating to latest program seem to have worked for the cars he's handled. But that's a rather small sample in the big scheme of things, and I didn't ask about his experience with A8 problems on other GM products.

Personal experience: Our 2017 Z51 A8 has just over 20k miles, operated in Drive 95% of the time and lots of long trips with lots of V4 use. It has the typical "wavering" +/- 50rpm or more in V4, but I can't feel or hear it. This Fall I had him do a drain/refill with the then-newest fluid as a precaution. No problems before, no problems since.
But again, a sample of 1 doesn't prove anything.

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Old 01-07-2019, 08:38 PM
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04TRCorvette
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Can we get them to change to the new transmission fluid under warranty even if we do not have any problems? I got my 2016 A8 last October and have no problems. Sometimes rough shift but nothing that's too bad. But was hoping to get the new stuff if its better. I have a range plugged in, i hated the V4 thing.
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Old 01-07-2019, 08:41 PM
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Once again Jim, you are confusing 16-NA-355 with the 18-NA-355 TSB. 16 is for the remote starter and 18 relates to shudder in the A8. If you get a chance also read "A8 Litagation" thread which is relevent to this shudder problem.
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Old 01-07-2019, 08:59 PM
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Originally Posted by MMD View Post
Once again Jim, you are confusing 16-NA-355 with the 18-NA-355 TSB. 16 is for the remote starter and 18 relates to shudder in the A8. If you get a chance also read "A8 Litagation" thread which is relevent to this shudder problem.
Noted and corrected, thanks.
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Old 01-07-2019, 09:04 PM
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Originally Posted by 04TRCorvette View Post
Can we get them to change to the new transmission fluid under warranty even if we do not have any problems? I got my 2016 A8 last October and have no problems. Sometimes rough shift but nothing that's too bad. But was hoping to get the new stuff if its better. I have a range plugged in, i hated the V4 thing.
A good question, especially since I've already paid once to get the then-newest fluid in hopes of preventing problems.
My guess is that the answer will be "No", unless GM does it as part of a settlement from the lawsuit.

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Old 01-07-2019, 09:12 PM
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Taking mine in next week to get it done before i install the 2300

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Old 01-08-2019, 07:09 AM
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I've got this problem, but my OCD cringes at the thought of anyone tearing into my new car to make so called "repairs"! I'm in Arkansas and my '17 Grand Sport has displayed this issue prominently, since DAY#1! Coming from a C6 with a 6 speed manual, and never having test driven a C7 Grand Sport with an automatic 8 speed transmission before I purchased, I didn't know if this wasn't normal operation for this model??? It didn't take me too long to conclude for sure, this is a defect! I've had to explain what to expect when ever I've let my wife drive the car. I have actually developed personal "driving techniques" to lessen the impact of the hard shifting, pushing, snatching and hesitation acceleration characteristics! I want to be a part of any litigation or resolution to addressing this issue!

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Old 01-08-2019, 08:14 AM
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Interesting, thank you.
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Old 01-08-2019, 08:22 AM
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Originally Posted by Stew24 View Post
I've got this problem, but my OCD cringes at the thought of anyone tearing into my new car to make so called "repairs"! I'm in Arkansas and my '17 Grand Sport has displayed this issue prominently, since DAY#1! Coming from a C6 with a 6 speed manual, and never having test driven a C7 Grand Sport with an automatic 8 speed transmission before I purchased, I didn't know if this wasn't normal operation for this model??? It didn't take me too long to conclude for sure, this is a defect! I've had to explain what to expect when ever I've let my wife drive the car. I have actually developed personal "driving techniques" to lessen the impact of the hard shifting, pushing, snatching and hesitation acceleration characteristics! I want to be a part of any litigation or resolution to addressing this issue!
I know how you feel, but you should bite the bullet and take it in. The fluid swap did wonders for my car. I'm hoping the issues don't return, but if they do I'll take my car back in and ask for the newest fluid.

Last edited by cstapp99; 01-08-2019 at 08:23 AM.
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Old 01-08-2019, 08:30 AM
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Originally Posted by Stew24 View Post
I've got this problem, but my OCD cringes at the thought of anyone tearing into my new car to make so called "repairs"! I'm in Arkansas and my '17 Grand Sport has displayed this issue prominently, since DAY#1! Coming from a C6 with a 6 speed manual, and never having test driven a C7 Grand Sport with an automatic 8 speed transmission before I purchased, I didn't know if this wasn't normal operation for this model??? It didn't take me too long to conclude for sure, this is a defect! I've had to explain what to expect when ever I've let my wife drive the car. I have actually developed personal "driving techniques" to lessen the impact of the hard shifting, pushing, snatching and hesitation acceleration characteristics! I want to be a part of any litigation or resolution to addressing this issue!
Would the dealer have let you take a test ride in a new Corvette? Mine said if I wanted to take a test ride, I had to pay for the car first, LOL!
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Old 01-08-2019, 12:28 PM
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some fluid will fix a design flaw? Miraculous!!!
.
You can call me a pessimist but, I tend to think the worst (I guess I am a pessimist). I would tend to believe this new (?; regurgitation of a previous approach) 'fix' just miiiiigggghhht be relaated to pending litigation. Maybe? I also think that multi-national corporations who put their share price ahead of all else (country, workers, and customers) will do the absolute minimum and stall the real, more expensive, solution.

Call me crazy.

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Old 01-08-2019, 07:47 PM
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When mine started the usual symptoms my dealer went straight to new TC. Been fine since
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Old 01-09-2019, 03:26 AM
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Originally Posted by Idaho Mark View Post


Would the dealer have let you take a test ride in a new Corvette? Mine said if I wanted to take a test ride, I had to pay for the car first, LOL!
I had test driven a C7 A8 base some months earlier, but not a Grand Sport. I purchased my car some months later, over the internet, in a different state 5 hours drive away.
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Old 01-09-2019, 09:47 AM
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What is cost for new fluid change if you had to pay for it yourself. A guy on another post suggested 350.00, is that close?? Thanks
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Old 01-09-2019, 09:49 AM
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Originally Posted by bjones7131 View Post
What is cost for new fluid change if you had to pay for it yourself. A guy on another post suggested 350.00, is that close?? Thanks
That's about what my dealer wanted to charge me.
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Old 01-09-2019, 10:11 AM
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16/C7Z
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Originally Posted by tcinla View Post
some fluid will fix a design flaw? Miraculous!!!
.
You can call me a pessimist but, I tend to think the worst (I guess I am a pessimist). I would tend to believe this new (?; regurgitation of a previous approach) 'fix' just miiiiigggghhht be relaated to pending litigation. Maybe? I also think that multi-national corporations who put their share price ahead of all else (country, workers, and customers) will do the absolute minimum and stall the real, more expensive, solution.

Call me crazy.
I wouldn't call you crazy but I would call you uninformed.

no design flaw. It was the decision to program the converter lockup pulse with in such a way to quell vibration that DID NOT respond well to the viscosity of the fluid.

it's been an ongoing issue they've been working on since the trans came out. Not just in Corvette.

I've had 2 A8s my buddy has had 3. They all do it to varying degrees.

the newer fluid last year fixed most of it. But theres a tiny bit remaining . Slight.

my car only had around 4k miles at the flush. The reason for the TC replacement is time.. if there are too many miles on the TC the fluid change may not correct the shudder feeling. But that's a case by case basis.

I've discussed this in other threads but quick short version - the issue can be tuned out of the trans. But it requires AFM off in ecm and a procedure in the trans controller or whatever it's called. And yes, it can be done but like many I refuse to tune my car because I do t want to fight with gm if the car breaks while under warranty. If you have a tune already? Then have at it.

I'm excited they are continually attempting to correct the viscosity and eventually the right formula will make it so you cannot perceive the pulse width of the lockup.

-not a design flaw - it's a software issue corrected via tuning and or fluid formula (viscosity). Which has been done by numerous manufacturers of auto transmissions since their inception (as explained to me at Carlisle bt a Corvette engineer discussing the issue).it is not uncommon and why you've seen things like Dexron then I II III IV etc etc. Over time.

ps. I would never want a 6spd over an 8spd. I've had plenty of both and the 6spd is archaic vs the 8spd in every aspect imo.

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Old 01-09-2019, 01:12 PM
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Originally Posted by 555ctsv View Post
My local dealer said they just received their first pallet of a new fluid today and have several cars lined up for the tsb. Hopefully this is the newest fluid the op mentioned? I asked them to get me on the list for this week or next week
Hey 555ctsv,
When you get the fluid change please write down the Mobil1 P/N and what the dealer actually did. I'm also in the Dallas area, who is this dealer with the new fluid?
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Old 01-09-2019, 06:32 PM
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Does anyone have a copy of the new bulletin? I found the following information (see attached) on the techlink site so it looks like a new way to flush the fluid along with a new fluid to solve the problem. Read the very last paragraph of the article and it talks about the 8 speed problem specifically.

John
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Old 01-16-2019, 10:23 AM
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I just picked up the car, paperwork says:

"Performed a trans fluid drain & fill 3 times per doc 18-NA-355"

Fluid part # said: "SYN LV HP ATF"
Also said: 19417904B
If you google "Mobil 19417904" it seems that is the part # for the bulk fluid in 55 gal drums.

I googled it and looks like it's just Mobil1 synthetic ATF.

I have only driven the car about 15 miles but it seems fine. I wasn't having any issues after we tuned out the 4cyl mode a couple weeks ago but figured it was best to get this taken care of before i dive deeper into mods

I went to Classic Chevrolet in Grapevine, TX to have this done

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Old 01-16-2019, 12:41 PM
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There have been multiple versions of that bulletin 18-NA-355, the latest one I've seen is dated Oct 11, 2018; and is not current.
According to my source, the part number for the very newest fluid has changed, and there may be a change in the actual procedure itself, so a revised bulletin should be out. But I can't find a copy anywhere. If anyone can get a copy, please post here!

See if you can get a copy of the bulletin they used. If its dated 10-11-18, then you probably got the older (but better than previous versions) fluid, and they may have not taken any additional steps in the latest procedure.

This may not be the dealership's fault, they can only use the latest info that GM is putting out to them. The GM communications in the A8 fiasco have been a real FUBAR.
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