[dradernh]

Originally Posted by f22b58

I have a used M Performance LSD on order, unknown mileage.
Any maintenance I should perform before installation?
Are the differentials and fluids good for lifetime?

1) That depends upon how you intend to use it. For example, if you plan on tracking your car, it might turn out to be worth your while to have a qualified shop open it up and evaluate its condition before you have it installed.

That might still be worthwhile even if you don't intend leaning hard on the car, as you can't know its condition without having it evaluated.

2) No, and no. Clutch pack-based LSDs eventually need rebuilding. The harder the car is worked, the sooner a rebuild becomes necessary. (You can tell it needs rebuilding when it starts slipping like a transmission's clutch does when it needs rebuilding.)

I don't know the fluid change interval for BMW's 2 Series LSD. I suggest emailing Dan Fitzgerald at diffsonline.com for professional guidance (https://diffsonline.com/contact-us.html). Among other services he provides, Dan rebuilds all sorts of BMW-specific diffs and pretty much knows everything there is to know about them.

I'm running a non-clutch pack Wavetrac LSD I got from Dan, and the maintenance intervals he recommended for the Wavetrac are: occasional autocross/track use – 12K; street-only use – 24K. It wouldn't surprise me if a BMW dealer would tell you that BMW's LSD has lifetime fluid in it.