[Shop-talk] Tractor Bearing Sizes

[Jeff Scarbrough]

1.  Maybe?  I don't know about your particular tractor, but I have rolled
the old main bearings (on a Triumph), just by pushing on the end without
the tank and grabbing it on the other when it starts out.  New ones just
roll in.  Requires all the caps to be loose.  If they are sticky, you might
get lucky by sliding a roll pin into an oil hole in the crank and turning
the crank to push the bearing shell out.  Note that this can introduce
problems that you didn't use to have.  Be governed accordingly.

2.  A good pair of sharp-pointed calipers may reach in the gap well enough
that, with a slightly dropped crank due to loose caps, you might get an
accurate journal measurement.   You could also use Plasti-Gage with new
bearings to see if you guessed correctly.  Could be expensive if you guess
wrong, though.  The shells *should* be a guide, if you can find an accurate
dimension for new shells.

Sounds like loads of fun for the New Year!



On Sun, Dec 24, 2023 at 11:57 AM Bob Spidell <bspidell at comcast.net> wrote:

> Merry Christmas Shoptalkers!
>
> I've pulled the head, pan and pistons from my ancient Ford 851 tractor
> (it was burning and belching oil and, well, it was time). Head actually
> not in bad shape; all but one cyl pass the (liquid) 'leak down'
> test--valves hold solvent in upside-down chambers--but I'll get a valve
> job anyway. Couple rod bearings worn but not bad, one pretty bad and one
> with all babbit(?) gone and copper substrate fragmented (prob would have
> seized in a few more hours). I plan to drop the main caps and,
> hopefully, extract the upper shells without having to pull the crank.
> Cylinder bores smooth but in good shape; I'm thinking ball hone and new
> rings.
>
> My questions:
>
> 1: Can I tap the crank's upper bearing shells out, then replace upper
> and lower w/o pulling the crank (not at option)?
>
> 2: Since I can't pull the crank, and it's not worth removing and
> grinding/polishing anyway, can I determine what size bearings to
> use--rods too--by just measuring the old bearings and getting an idea if
> they're over/under and, if so, by how much?
>
> All answers appreciated.
>
> Bob
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