Squatting on low-speed, tight turns caused by the rear differential or transfer case

[aidenjohanssonim]

It seems like my 2019 M850i coupe's transfer case or rear differential is the source of the trembling or vibrations I've been feeling. Initially, I thought the problem was with the rear differential, so I took the vehicle to the dealership to get the diff fluid replaced and the adjustments reset. Mileage on the odometer reads 100,000. I am now considering having the car serviced for the transfer case because it did not resolve the issue and I suspect it may be emanating from the center of the vehicle. On previous models, I have seen videos showing how to repair this issue by changing the fluid in the transfer case. At low speeds and tight curves, such in a parking lot, when I'm at or near full steering lock, it becomes evident. Has anyone else experienced something similar?

[olivia_patelh]

Your TC should be fully open by default at moderate speeds, as those in a parking lot. Signs of a failing CV joint, such as high angles and shuddering, are more likely to be present. The nature of your work permission order is beyond my comprehension. "I hear zebras, Mr. Dealer. Please." The same as YBT.

[aidenjohanssonim]

It was my job to re-learn the adjustments and swap out the M Sport E differential fluid. You can't call it a CV joint. After looking it over, they said to replace the rear Guibo since it's showing signs of cracking; however, I seriously doubt this is the source of the issue. Draining the transfer case fluid, changing the fluid, resetting the system, etc., is my next work order.

I have read many articles on this, so it seems to be a well-known issue. We don't know if the fluid change will work for this problem or not.


Anyone interested can see a video that demonstrates the fluid change procedure and includes comments and follow-ups from others who have used it to solve their own problems.

Your remark about zebras leaves me bewildered.

[aidenjohanssonim]

https://www.youtube.com/watch?v=dyGa5GFxELM

[aidenjohanssonim]

Furthermore, the video-mentioned known issue is detailed in the BMW SIB 27 02 20, which applies to several models, including the M850i.

[aidenjohanssonim]

https://static.nhtsa.gov/odi/tsbs/2025/ ... 2-0001.pdf

[aidenjohanssonim]

Has anybody else seen this and been successful in resolving it?