51 B bearings question

Bellwood · Feb 24, 2018

Hello all, I'm a newbie to old tractors and rebuilding my first. Every thing I'm doing on this is a first for me, but enjoying it! I am replacing bearings on connecting rod/end caps. On the bearings, what is the purpose of the notch on the one end? And do the notches need to line up a certain way with rod to the end cap? Thanks, I'm sure more questions to follow!

Bob · Feb 24, 2018

The tang on the bearing insert engages the notch in the rod, cap, or block to prevent the insert from turning/"walking" in the bore.

As you probably already know, the rod and cap need to be kept in the same relationship to each other as when the "big end" of the rod was honed to final size at the factory. Same with the main caps... need to go in their original position and orientation. HOPEFULLY they were match-marked at the factory or by the previous guy in there, or YOU marked them before removal!

CAREFUL installing the inserts, often one of the pair for each journal has an oil hole and/or a groove that must be installed in the correct location (top or bottom) or rapid destruction will occur at startup!

matthies · Feb 24, 2018

Are you sure you have new enough rods for inserts? You might have babbit bearings(molded to the rod and machined). If the rods are new enough you should see the same notch in the rod and cap as you see on the new bearings.

Mike M · Feb 24, 2018

John Deere made a fantastic service manual that covers that model. I forget the manual number but I would not tear one apart without first reading this manual. It covers theory of operations and has plenty of good pictures too.

51 B bearings question

Bellwood

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Bob

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matthies

Well-known Member

Mike M

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