BMW xDrive Front Differential Bearing Kit 31507533971

This kit covers the bearings and seals inside the front differential on BMW xDrive all-wheel-drive cars and SAVs from 2006 to 2020. It is listed under BMW front diff numbers 31507533971, 31507533975, 31507533977, 31507534720, 31507555885, 31507572052 and 31507592002, and fits xDrive versions of the X1, X3, X4, X5, X6, 3 Series, 4 Series and 5 Series with the 2.0L four, 2.5L six and 3.0L six.

Included are the front pinion bearing (STS 3572 LFT / 3579 Z pattern), the rear pinion bearing (SAC 3064 pattern), both carrier bearings (7542102 pattern), a pinion oil seal, two carrier side seals, a crush sleeve and a securing plate.

The front diff on these cars is known for a whine or hum that rises with road speed, and for weeping at the side seals. Rebuilding the unit with new bearings is far cheaper than a new BMW front diff. With the diff on the bench, mark the housing halves and note the carrier shim stack, press off the old bearings, and install the new races and bearings without mixing up shims. Set pinion preload against the new crush sleeve, reassemble, check backlash and tooth contact, then fit the side seals and refill with the specified gear oil.