stevettec7

Follow-up to my post #673:

Got mine back last Monday. The tech said my valve body had a legitimate failure, so they replaced it. Well, that ain't it!! ---harsh shift still exists. Makes me wonder if they tried to do a cold test before calling it good?
I just noticed the only time my car gets a break as my "daily driver of choice," is when I'm in for service.

Dave-T

Got the car back. They did a triple flush and added the new fluid per the service bulletin. So far no shuddering. Not sure about the delayed engagement, need to wait for a cold start.

767guy

It is possible the reason your car still has harsh shift issues, which is normally a TC fault, is because you do not have the latest TC version part # 24280631.
You posted that the Transmission ( which includes the TC) was removed at 24,500 miles. If this repair was done prior to about mid December 2016 then probably you have the older style TC part # 24279495 in that transmission.Starting in about mid December 2016 or early 2017 TC part # 24280631 and the new fluid became available.
My early build 2015 base A8 had three transmission tear outs for harsh 1-2 shift first drive of the day, flares , and frequent harsh upshifts and harsh downshift 3-1 coming to a stop.
The original TC that came out of the car was 24279495 and that same part # was used in the first and second tear out and my symptoms did not go away. Finally in Feb 2017 Stingray Chevrolet in Plant City FL did TC replacement number three and installed the newest version TC part # 24280631 as well as the new fluid. Only then did the previously mentioned faults go away.
It's a long shot but it seems to me if your last transmission/TC is prior to about mid Dec 2016 or Jan 2017 there is a good chance you do not have the latest TC version which may be the root cause of your problems.......good luck with the fix and please post results for us, tks.

hotdog2020

2016 Corvette Z51 A8. I just got back from the Gulf Shores, AL. While driving the Corvette down there I noticed the car shuddering pretty bad. We were driving from St. Louis and coming through Mobile, AL we hit some Friday afternoon traffic. Man was it irritating. Seemed like light throttle around 20 to 65 mph, the car would shudder. I thought at 1st it was a tire out of balance but I figured if that were the case the car would vibrate all the time. On the way back, I set up the DIC to see if the shudder happened during the transition of V4 to V8 but it didn't seem to happen at that point. I really notice it during light throttle after slight coasting or when the car isn't loaded and then slight throttle. I'm going to have the dealer look into it. I daily drive my car and just noticed this. I have 19,544 miles on her.

NSC5

The primary and problematic shudder isn't at the tip in point between 8 and 4 cylinder operation but with sustained operation in 4 cylinder mode. Next time you notice this put the transmission into manual mode (prevents V4 mode activation) to see if that cures the issue.

Hope you enjoyed Gulf Shores! I grew up not far away in Gulfport MS and have a lot of good memories of the beaches along that section of Alabama and Florida

hotdog2020

Gary, Did you find out from the dealer what the issue was with your A8. I have the same issue. I apologize if you responded already but I tried to search and didn't see an update. Just curious as I'm going to have to call the dealer tomorrow. Thanks, Keith

hotdog2020

Thanks for the information. I'll try that tomorrow. Yes, it was a great time! We Love the beach. Making memories with the grand kids and jellyfish. LOL They didn't get stung but actually got to touch one some teenagers caught in a net before they released them out farther. The GK's think they're a big deal now. Haha !

NSC5

I was lucky never to have a bad encounter with a jellyfish. The Portuguese Man of War variant (not a true Jellyfish) look beautiful in the water but they are the ones to truly avoid.

stevettec7

767guy

What was the date that the transmission was replaced at the 24,5000 mile point ??

stevettec7

767guy

My experience was that when I received a new transmission ( second tear out) the service manager advised it included the TC.

stevettec7

That's what I was afraid of. I'm sure that's what my adviser and tech said during that maintenance action last year. Today the tech duplicated the issue and gathered data...Now I'm waiting to see what the GM reps recommend. THIS IS PURE INSANITY!!

Trihawk

13,000 miles since triple flush and all is good.

TC shudder at 61,000 miles. Triple flushed 11/2017.
Current mileage 74,000+

stevettec7

jimtreber

My 2019 C7 has a flare between 1st and 2nd (in drive) whenever first driven in the day. After the single flare, It is fine all day afterwords. It just happens after the first startup in the morning. The flare only lasts about 1 second but is annoying. To avoid it, I start in manual 2nd gear. After rolling I put it in drive and it's fine after that all day. It has done it since the first hundred miles. I was hoping it would go away but now at 2000 miles it is still there. I haven't been to the dealer yet as I expect to take it soon for an oil change. Any thoughts?

joemessman

Not normal. Be sure to mention it when you take it in.

jimtreber

As I looked through the forum, I find it is a known issue. I tried the posted M 1-2-1 and it works. At least until i take it in to the dealer in the near future.

NSC5

I thought GM would have fixed this by now; I use the 1-2-1 shift with my 2016 Z06 at the first start but I expected by now GM would have issued a software update to force a partial pre-fill of the actuator at startup. Although the "jolt" from the flare isn't bad it isn't doing the clutch pack any good and over time it could create a problem with that pack due to excessive initial slippage followed by a hard lockup. Apparently the TCM either doesn't use separate cells to store the parameters for the shifts under different conditions (i.e. cold start, low speed) so it can't unlearn this behavior because the great majority of 1-2 shifts are normal which swamps the correction from the learning algorithm that would be applied if all 1-2 shifts were like the initial shift from cold start.

NineVettes

I am looking to get back into a Corvette and looking at some new C7 GS cars tomorrow. At this point, I would prefer an A8, but in doing some research here, still a bit concerned/confused. The dealer has a new 2018 GS A8 with a build date of 7/17, a 3LT that they are offering 10k off of. Were the A8 problems pretty much resolved by GM by 7/17? My research seemed to indicate that last G updates were around 12/16? Is AFM still causing a problem with theses cars? As an aside on this particular car, I am thinking more than 10k should be taken off the MSRP?

The second GS I am looking at there is a 2019 GS LT2 A8. Were there any upgrades of the A8 between 7/17 and the 2019 cars?

I have also heard that when using the paddle shifters, this tranny shifts pretty slowly? Still the case for '18 and '19 cars?

Thanks in advance for your inputs!