BMW Rear Differential Flange and Pinion Seal Tool Kit

A leaking pinion seal on a BMW rear differential is a common job, and it goes wrong in two places: holding the flange still while you break the pinion nut, and getting the new seal in straight. This 9-piece kit covers both with the tools that match the BMW special tool numbers, all on a 1/2-inch drive.

The set includes the output flange support wrench (23 00 20), the differential flange nut wrench (33 50 50), the drive shaft inner nut wrench (33 50 40), the drive shaft seal sleeve (33 50 80), the oil seal installer (33 50 90), two locking dowel pins, and three spline sockets (33 50 60 pattern) in 27, 34 and 37 teeth. The 27-tooth socket fits M2, M3, M4, M5, M6 and M8 differentials, the 34-tooth fits the 3, 4, 5 and 6 Series including E90, E91, E92, F30 and G20, and the 37-tooth fits the 7 and 8 Series and X5, X6 and X7. RWD and xDrive cars both use the same pattern.

On the car: mark the pinion nut position against the flange before you touch it so you can return to the same preload, lock the flange with the support wrench, and break the nut with the matching wrench. Pull the flange, pry out the old seal, and drive the new one in with the installer. The installer only bears on the metal case of the seal, so it goes in square and flush instead of cocked, which is the usual reason a fresh pinion seal weeps again. Reinstall the flange and run the nut back to your mark. The work is done with the differential in place, so there is no need to lower the rear carrier or disconnect brake lines.

The spline sockets are heat-treated alloy steel rated for 250-450 Nm, so they will not spread on a tight pinion nut the way a cheap socket will.