Broken Pinion Stem

The drive pinion stem can break at any time if the differential pinion bearing preload is not set up properly. If there is no preload, the differential pinion bearing will turn relative to the axle shaft. This galls the roller shaft and generates heat which can draw the temper away from the shaft.

Too much preload also generates bearing heat with the same result. The break normally occurs between the two differential pinion bearings.