A8 shudder, stutter, warble, rumble strips
 

My 2015 Stingray 3LT had been at the dealer since October 18. Got it back last night. They replaced the torque converter after a service engineer came to the dealership and drove it. Works fine now. Service Bulletin 5337F.

Please keep us posted periodically and especially after you drive it for a few thousand miles. Very curious if the fix remains the fix.

what specifically was the bulletin for? My dealership says they have replaced alot of torque converters. Did yours have the warble sound?

No sound, just vibration (stuttering in V4) and some shifting issues.
I never read the actual bulletin but the paperwork they gave me referenced it.

I was wondering if this was ever an issue after the repair. I just got my 2015 3LT with Z51 and have been able to isolate this issue to the transition between V4 and V8. Seems like it definitely could be this issue after reading the bulletin.

I don’t know if the previous owner ever did the Service Bulletin and if not, I’m wondering if it would be covered under my GM extended warranty. Thanks for any insight!

I also found this bulletin which looks like it’s from December 2018 and has specific instructions for the tech:
https://www.midenginecorvetteforum.c...ission-shudder

Differential service got rid of the warble noise for me.

perfect.

Do the 2019's have this auto trans. problem too?

The bulletin specifies two models of the A8 transmission (8L45 and 8L90). I’m not sure what years those apply to, but I know it does apply to my 2015 Z51. The OP on the site I linked to mentioned that “90% of users with A8s don’t have yeh issue...” which I suppose is good news. I’m going to check in with the dealership this week and see one this applies, specifically with my GM extended warranty.

Great news! :thumbs:

Anyone in norcal recommend a good dealer for this?

Quick update that I scheduled the service for tomorrow and upon calling in, they knew exactly what I was talking about. The SA told me that they used the replace the torque converter but were still getting a portion of those customers back with the issue.

They said that now they flush the system with a new formula of transmission fluid and that resolves the issue. This is the solution referenced in the Dec 18 service bulletin I linked to above. I was glad to hear that they recognized this issue immediately over the phone and have a solution.

I’ll report back after I pickup the car and drive it a few hundred miles.

FYI it’s Greenacres Chevrolet in Lake Worth, FL. My SA is Mike Fox.

https://cimg5.ibsrv.net/gimg/www.cor...d10d07498.jpeg
Had mine done yesterday, so far the shudder is gone. New SB, same number as the one released in Jan 2019 is now dated March 2019 with no change to the process.

We'd be happy to confirm the issue and proceed with the repairs if the shudder meets GM's criteria. The newest version of the bulletin requires a snap shot of the data showing the vibration is above a certain threshold. If it is, we're good to go.

With that being said, 80% of the vehicles we road test (Camaro, Corvette, Cadillac, Truck and SUV's) do not meet the minimum threshold to perform the flush. We literally see at least one vehicle per day for this "issue" so it's nothing new to us, but we have to be able to verify (with data) that it's severe enough to warrant repairs. Many of the people coming in have a slight shudder, but they read on the forums about it and more or less just want a free fluid flush.

If the vehicle is under bumper to bumper warranty, GM will pay us the 3/10ths of an hour diagnostic time even if we can't prove the level of shudder is above GM's limit. If the car is outside the 3/36 bumper to bumper, GM does not allow us to submit the diagnostic time if the car is not severe enough so that time is the customer's responsibility. If the shudder is excessive and we can obtain the snap shot, all costs are paid by GM and the customer is not responsible for anything.

Thanks, this is helpful.

How long did the service take start to finish?

2 to 3 hours, I’m not sure, was not in a hurry, just wanted it done right.

http://gmauthority.com/blog/2019/04/...ission-defect/

GM Hit With Class-Action Lawsuit Over 8-Speed Transmission Defect

Interesting - thanks for sharing!

I am pleased to report that after the service on Wednesday, I’ve driven ~150 miles and it’s like a completely different car! Not only is the shudder problem gone, but my shifts in M mode are completely smooth as are general shifts in automatic. This is specifically evident in Touring mode where I had just assumed since getting the car that it was jerky in Touring mode all the time.

I’ve also noticed less of a lag in shifting between reverse and drive, and no shaking/shudder when switching between V4 and V8.

The service took a full day.

I just bought a 2019 GS with the auto and have noticed that when it is in 4 cylinder mode, I get a shudder which happens about once every 30 seconds or so from the car. It is not severe, but it's enough to get my notice constantly. It also happens when it drops to V4 or up to V8. Doesn't happen in 8 cylinder mode. I really hate buying an expensive brand new car and having issues. Didn't have a single issue with my 2012 GS.