[JFP in PA]

Originally Posted by White, Walter

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.

Which completely fails to explain why the IMS Solution with no movable ball bearings has proven to be the most brutally reliable replacement for the single row IMS.....