John deere A main bearing

Tstoner

Member
First off I apologize for the novice question I'm about to ask. Long story short I acquired my grandpa's 44 A. I'm currently restoring I recently took the crank shaft out it was pretty rusty due to the cover missing on the tractor. I took it in to be welded and brought back to standard size. ( it was .020 under already). I'm not familiar with these babbit shimmed main bearings. They seem to be in pretty good shape. My question is if I bring the main journals back to standard size can just adjust the shims for clearance? Or is it necessary to find standard main bearings? Also how can you determine if the babbit material is still sufficient? I say the main bearings look good but that is just Me saying they are smooth
 
I'm working on my 51 A right now. Crank is still in, pistons and rods are out and showing hardly any wear. How did you determine .020 under? If it
was worn that much I doubt the mains are OK. How do the rods and journals look?
 
(quoted from post at 15:04:34 02/20/23) I'm working on my 51 A right now. Crank is still in, pistons and rods are out and showing hardly any wear. How did you determine .020 under? If it
was worn that much I doubt the mains are OK. How do the rods and journals look?
I don't think it being .020 under is from wear. I measured the rod journals and main journals on the crank and they were all consistently. 020 under standard size so I figured someone at sometime had it machined. As far as the rods unfortunately I don't have them the tractor is missing the engine all I have is the crank
 
Check the many John Deere groups on FB. A lot of parts being sole there. Unless I misunderstood, I'm puzzled why you had the crank welded when you don't have the pistons and rods.
 
(quoted from post at 14:30:02 02/21/23) Check the many John Deere groups on FB. A lot of parts being sole there. Unless I misunderstood, I'm puzzled why you had the crank welded when you don't have the pistons and rods.
I'm not looking for parts just am unfamiliar with these babbit style bearings. Was just looking for some input. Not sure what the issue is with me bringing the crank back to standard not having the rods. As far as I understand the rod bearings are adjustable shimmed babbits as well
 
No issue, it's yours to do what you please with it. Your first post said you're restoring it, then it has no engine and you're not looking for parts.
Not being critical just that I'm a bit confused.
 
(quoted from post at 15:58:49 02/21/23) No issue, it's yours to do what you please with it. Your first post said you're restoring it, then it has no engine and you're not looking for parts.
Not being critiofcal just that I'm a bit confused.
I understand. When I made my first post I was just looking for information on the shimmed babbit bearings as I am not familiar with them. When I got my tractor I knew there would be a lot to do so I broke everything down and started at the rear and working my way up. I got to taking the crank out and due the the cover being off for so long the crank was pretty rusty and minor pitting so I decided to have it welded and brought back to standard size. The main bearings I took out of the tractor, in my opinion Visably look good but wasn't sure if there is anything I should look for in the babbit style bearing that would tell me otherwise. And I can imagine they are pretty expensive so was trying to use the original bearings
 
Since you have the mains out measure the shim packs then bolt them back together with the shims as they were when you took them out. You can measure
the IDs in several directions and see how they wore. Post some pictures if you can, that will help. With the crank at -.020 there could be a lot of
shims removed to compensate.
 
When you get replacement rods go with insert bearing style rods. Then you can get standard bearing to match the crank. As noted above on the mains, .020 is a lot to shim to. Since you have the mains off the tractor, setting oil clearance before assembly is an excellent plan. You may have to get replacement main bearing holders that use insert bearing or use the later bored bearing.
 

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