[arpad_m]

Originally Posted by 18ss376

What is A8 shudder?
Mine shifts super smooth, sorry old guy here.

In a nutshell, the programming of the eight-speed automatic (A8) transmission and allegedly the original trans fluid used until early 2017 causes torque converter friction material to slowly erode and discharge into the fluid, which then results in a shudder similar to driving over rumble strips in 7th and 8th gear under low engine loads. It typically starts in V4 mode and/or driving up on gentle inclines, then progressively gets worse, eventually affecting V8 mode and most highway driving. Some cars exhibit this very soon, others appear to be unaffected for tens of thousands of miles, but it is unknown how long they will last.

The initial workaround was a triple flush of the trans fluid, followed by torque converter replacement. This was finally deemed insufficient by GM, and a permanent engineering solution was promised to be made available in Q1 2019.

Many owners managed to successfully fix it by reprogramming the trans (and flushing the fluid, if needed), but this voids the powertrain warranty and may not help if the physical damage to the torque converter was already done. (The A8/A10 transmission control module software is protected on 2017+ models, and the encryption has to be cracked first in order to upload a new tune, which will definitely be detected by a dealership.)

[Turbowolf71]

2016 here. Mine started right around 9500 miles. Took it in for the flush and so far so good at a little over 12000 miles. I'm not holding my breath that it will last though especially since the rear differential is acting up again. I had the same problem with that that some folks here had and took that in for the flush at 1200 miles and now it's back. So off to the dealership I go.....

[HyperBlue2017]

Bought mine used with 20k on it and it has the "shudder" when it's going from a v4 to a v6, don't really notice it going from 6 to 4..
Don't know how long it was doing it before I got it.
I was sure what it was until I found it in the forums...

[bereic]

Originally Posted by arpad_m

This was finally deemed insufficient by GM, and a permanent engineering solution was promised to be made available in Q1 2019.

Is there any news on this from GM?

[HCI2000SS]

The bulliten specifically states what the dealer needs to do. If they choose not to follow that then I'd find another dealer