2017 G90 Ultimate AWD - transmission issue

[thirstforspeed]

Hey all, just posting here for posterity, and to create a record of my experience in case anyone else has a similar problem in the future (as these big bois leave the warranty period and enter 2nd, 3rd owners hands.
The car: 2017 G90 Ultimate 5.0L AWD, 72,800kms

The Problem: when at merge speeds, in 3rd gear, ~3000rpm and larger throttle openings (~75%) the transmission would make a shudder multiple times through the gear into 4th. It feels like driving over expansion joints on a bridge, and it would not create a jump in rpm, so i dont think its a torque converter thing, but it feels as if the 3rd gear band is slipping and catching. There was no forbidden glitter in the trans filter ahead of replacement (Genesis checked the filter on a prior visit). They also tried relearning/reprogramming, but that did not address the issue.

The solution: multiple trips to the dealer, and escalated to Genesis HQ for testing with their engineers to root cause the problem, but ultimately Genesis HQ recommended replacing the transmission. It was replaced under warranty (had a valid CPO 1yr powertrian warranty). Genesis has been great through this whole thing too. Didnt recommend throwing parts at it or needless services. A+ service experience.

I dont know exactly what was wrong in the transmission, but it was all handled under warranty, so thats out of my scope to understand.

 

[rick3242]

Very similar thing happened to me on my 2010 tundra immediately following a flush at 100K miles. So the flush power moves the trans fluid and can deposit shavings etc in the vanes of transmission which causes transmission shudder - they did two more flushes and it eventually cleared itself.
I will never get another transmission flush - i will only get drain and refills.