Quote:
Originally Posted by soling222
1. The early double row ball bearing (up to about MY2000) in the M96 engine has a very low, but real, failure rate (maybe <1%).
2. The first small single row ball bearing (MY2001-2005) in the M96 engine has the highest failure rate (about 8%), and is the smallest of the three ball bearings.
3. The second larger single row ball bearing (MY2006-2008) in the M97 engine has a low failure rate to date (about 1%).
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To be fair, let me point out a few differences I have observed in these bearings.
1. The earlier 2 row bearing is longer and as it is pressed into its bore, I think it is more self-aligning, because of its length. Even if the back of the bore is not square, it will more-or-less be square in the bore.
It also uses the W or crown type separators (cage, but with this type I think separator is a better term for the W type).
2. The single row bearing is much narrower, and when it is pressed into its bore, I think misalignment could be a factor. If is is pressed against the rear of the bore, and that seating surface is not square to the axis of the shaft, misalignment can again be a factor. This bearing also uses the J type cage.
3. The larger later model bearing, being both larger in diameter and longer than the earlier single row, could be less susceptible to misalignment I think, and, because of its overall larger size, I think it is probably more tolerant to the torsional loads created by possible misalignment. It too uses the J type cage.
This is why I think the ball bearing is used in the design. They can accept a degree of torsional loading, created either by misalignment on installation or by deflection of the shaft.