Mini Cooper Drivetrain Issue

I had something similar happen with my Mini. Unclean shifts and all. Have you checked the transfer fluid level? Maybe the transfer case oil needs changing? It could be a simple fix, but I'm not sure. I'd hate to see you tear into it if it's something easy.

When you experienced similar symptoms, did you also observe any unusual noises emanating from the drivetrain? And was the mechanical wear evident upon inspection, or was it diagnosed primarily through the process of elimination after addressing potential lubrication issues?

No unusual noises that I recall, just the rough shifting. I didn't do the inspection myself. I just took it to the shop, described the issue, and they figured it out. They mentioned something about the transfer fluid being low and signs of wear. I'd suggest having a mechanic take a look, especially if you suspect mechanical wear.

The Mini Cooper's transfer case fault was indeed due to mechanical wear, specifically defective gears as suspected. After replacing the damaged components and replenishing the transfer fluid, the shifting issues have been resolved. The total expenditure amounted to 330€. Thank you for your insight; it proved invaluable.