Model A rod troubles

Split Shot

New User
What is the best way to replace the rod bearings the crank is great the babbit is a little worn .I heard some banging noise so I stop it .
I was thinking if I replace them with STD. size and take out the correct amount of shims .would this work . What other ideas have worked
 
Where do you intend to get std size. Babbit is poured.
You have to find a shop that can do that.
 
Well there for sale right on this web site. What started all these problems was the screen down in the bottom of the crankcase was all plugged up . I pretty sure I lost pressure But I was thinking again if those bearings are notched then the rod and cap need to notched so the bearing won't spin. To bad there is no picture of them.
 
I replied on your other post, ask these John Deere experts. I have been told you can use rods for a John Deere 60, which use insert bearings.
 
They are notched. I have a set of rod bearings out of an A in my toolbox. These are out of a late styled A, 1948.
 
Babbit bearing employ divets into the the housing where they live in order to prevent 'spinning' you claim will happen without notches. Properly called keys they are tapered at the bottom such that the babbit can't come out of there or spin, you need a rose-bud just to recover that babbit. Just guessing, but I would guess that there are three keys in each half of one rod bearing.

So the standard operating procedure for babbit bearings at this point is to buy some plasti-gauge and start removing shims until you are at the clearance you want. Unless you need to spend more money than $10 for plasti-gauge.

I see the same screen plugging sludge even after only 10 years with top of the line diesel high detergent motor oil and frequent oil filter changes. Tending to think it's the nature of the beast and crankcase cleaning with a parts brush and the oil pump on the ground is required maintenance that a few gallons of kerosene is supposed to take care of. If you'll look, you can see it really doesn't do an adequate job without the elbow grease and the parts brush.
 
JD parts catalog shows replaceable inserts in various sizes for A's with serial #488000 and up. For serial number below that they show an exchange for the rod. The 51 A I have has replaceable inserts. This tractor was bought new by my dad and I have done all of the work on it except for when he had the power block and water pump put on it very early in its life.
 
If they are indeed babbit style rods if the babbit is still intact and not flaked out bad or to the edge you should be able to reuse them. To adjust them measure the shim packs and make sure the top and bottom shim packs are equal thickness. Then you simply peel off 1 of the .003" shims from the top pack and 1 from the bottom pack keeping them equal. Then reassemble it all and check as you tighten up the nuts that the crank turns free. If you get the nuts tight and all still turns free then take it back apart and remove 1 more shim from each top and bottom and repeat until it gets tight or snug as you turn the crank. Then you simply ADD back in 1 more .003" shim into the top and bottom and retighten and you should be free turning and good to go.

Now if it has factory insert rods these are the same as from a model 60. Crank will NEED to be measured to get the correct bearings and find out how out of round it is. These bearings are not very forgiving so they NEED to be right on the specs.

Then there is another possibility. It could have the original babbit rods that have been machined out to accept inserts. Not common but can be done. These usually still have at least 1 of the thick shims/spacers in top and bottom and ARE NOT adjustable.

I have found plasti gauge to be about useless on 2cyls. because you usually have to rotate the crank some as to get a torque wrench onto the nuts due to close quarters. You cannot move the crank while using plasti gauge.
 

Thank you for posting these notes as I am in the process of changing babbit style rods out with the insert style (I have both on hand, the babbit had some nicks at the rod cap). As I was looking at the crank this morning and my plastiguage, the thought crossed my mind of how am I going to accomplish this!
 
Also note the babbit type are a lot more forgiving of an out of spec. crank. Insert types need to be in spec. because you can't adjust them.
 

Mike, I had bought a set of 60 rods for my 52A but I am double thinking that now. I'll have to check very closely this weekend when I am getting measurements. Not to highjack this thread, maybe it is useful information for the OP as well.

Would this amount of damage be considered acceptable? Usable?
32159.jpg
 
Well I've seen a lot worse. LOL. I was told by an old JD mechanic and ag instructor that as long as you do not have chunks out that go to the outer edge you should be ok. I think that if they go to the outside edge then an open path could let oil out and loose pressure ?
That rod should be fine. Especially if you are using it light duty.
Now if your crank needs ground then that is where having insert rods is the best so you can buy the matching undersized bearings.
I have cleaned up some corroded ones before in my solvent tank and using scotch brite or fine wet sandpaper like 600 grit.
 
(quoted from post at 13:17:09 01/21/16) What is the best way to replace the rod bearings the crank is great the babbit is a little worn .I heard some banging noise so I stop it .
I was thinking if I replace them with STD. size and take out the correct amount of shims .would this work . What other ideas have worked
The bearing issues reminded me of the 51A I bought as a restoration project. It seemed to be running OK, but needed a basic overhaul. Teardown showed #2 Rod was poured babbit with a standard dia crankpin, #1 Rod was an insert rod with a .040 undersized crankpin, the insert was shimmed for clearance just as if it were a poured babbit bearing. There was little to no thrust face left on the flywheel side main bearing, only a short section of "tin foil". The flywheel wouldn't come off, then found out it was glued on with epoxy, took about 15 blows with a 10# sledge to remove. Didn't salvage any of the parts, went ahead and bought 60 rods and a crank & flywheel with good splines from the JD parts recycler. That tractor showed me, with ingenuity, understanding of the mechanics, and reasonable bearing clearances, these old engines keep right on running. Transmission, same deal, the oil looked more like grease and I ended up replacing bearings on the c-shaft and sliding shaft, but it was still running in all gears. The handiness factor on these old tractors, as in getting a wrench or socket on things isn't there, but the tuffness factor certainly is.
 
Well Here's what I did with the plastic gauge I set the cap and rod where it would the easiest to tighten down then I put just a little oil on the crank and stuck the plastic gauge in the oil just a drop will hold it in place. slide the cap on and tighten it down.
Then remove the cap and check it thickness of the plastic.
 

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