Re: Flanged Rod Bearings

Posted by Tim Cole On 2009/4/22 18:49:18

Theoretically, the hardness of the bearing material should not matter in a properly designed motor. Rolls-Royce used a very soft babbitt with high longevity. It was softer than plastic. Packard bearing technology followed the research published by Wright and Taylor in 1925 by which bearing characteristics technology became fully developed. Not all manufacturers followed this technology - most notably Lycoming - and suffered from poor connecting rod bearing life. The Packard V-12 was not designed following Wright and Taylor and thus had more rod bearing problems than Packard eights.

To determine which bearing method works best requires a teardown. Even on these motors with new parts the results may be pretty surprising. I did some repair work on a V-12 and found the condition of the inserts downright shocking. I attribute this problem to infrequent oil changes and lousy filtration.

The principal advantage of the insert bearing is superior heat transfer and cooling especially at high RPMs. This is achieved via the pre-loaded nature of the bearing insert.