How to ID main bearing size?

Yeah, this sounds like a stupid question, and I've had plenty of experience rebuilding engines.
Here's my problem. I've got a Ferguson TO35 engine torn apart and am trying to do an "in-frame" motor job. This all began because a sleeve was leaking coolant into the oil pan.

Engine is the Continental Z134 gas. So, I pulled the pistons and rods out and the rod bearings are all marked .020. So, that's an easy one - .020" undersize bearings. But, the mains have no such numbers. Just FM2227 SB. So, I assume FM is for Federal Mogul. I can't find a listing for that number in any database. I had originally thought that maybe the "SB" stood for standard bearing?" But, now, I'm not sure. Bearings looked good and I was just going to reuse them - so it didn't matter. But, just checked and they've got .0035" clearance (too much). So now I want new ones and can't figure if they're standard or some undersize that is NOT stamped on the bearing. I can't get a mike onto the crank journal while it's still in the tractor. I did attempt a crude measurement with calipers and tape measure and with this very poor measurement - the crank journal seems to be around 1/32" smaller then standard. That could easily be .020" or .030" under.

So, at this point, I have no idea what bearings go get. Anybody ever come across an undersize main bearing that was not marked undersize?

no,the ones i have seen were stamped with the under size no.so if they are not stamped a person would think them to be standard.maybe only the rod journals were turned.your kind of between a rock and hard place, because you need the crank out to get the measurements. measure main journal, and torque cap to block with brg. in and get a measurement with inside mic. or take a chance and get standard brgs. and try them? what do you have more of money or patience?

You may have to pull it all apart and drop the crank so you can mike the crank and fit the right bearings to it. You dont think they are stock bearings? I wouldnet think someone would have turned the crank in it, but I guess you never know with .0035 clearance., that much wear?

look on the counter weights most crank grinding shops stamp the grind there useal mark as R and M

i wouldnt call it that much wear, and it would probably run a long time yet at .0035 clearance.just use a heavier vis. oil.them old wk40 mccormicks i have measured from .008 to .010 on the mains for wear. they had to of run to wear out that much. the spec. was .0025 for the mains.if its just a putts around tractor it will still run a long time.

Go to a machine shop & check their books for the wall thickness at crown. That is the thickness of the standard insert. You have to use a small round rod on the inside to mike it. Then subtract the rod size from the total. They should know how. If it is close to .010 more than standard the crank was turned .020. Mike the insert close to both ends & use the highest reading.

I would have the book here but need the crankshaft forging number to make sure.

Check journal Dia. as best you can with calipers, should get you in the ballpark as crank would have been ground in even increments(.010, .020, .030 undersize, etc.). From that you may be able to determine if a re-grind is needed by visual or feel inspection(are the journals smooth, no ridges, obvious wear, etc.)Careful use of calipers may also show if you have a journal more than a few thousands of out-of-round. You may be able to plastigage the existing bearings, then compare their thickness to a new bearing. This is about the best you can do without removing the crankshaft. Good luck with it.
Paul

JD,

My book says it is a flanged bearing and is

used in position #2 , and unmarked shells are

standard.

If you are really in doubt I have a mic

to measure the main journal with the crank

in the block. It is quite technique dependent.

picture of it here ,holler if you need it.

george

JD,

Forgot this in the other post.

SB is the bearing material , it stands for

steel back -- babbitt lined.

george

(quoted from post at 20:36:41 01/06/10) Yeah, this sounds like a stupid question, and I've had plenty of experience rebuilding engines.
Here's my problem. I've got a Ferguson TO35 engine torn apart and am trying to do an "in-frame" motor job. This all began because a sleeve was leaking coolant into the oil pan.

Engine is the Continental Z134 gas. So, I pulled the pistons and rods out and the rod bearings are all marked .020. So, that's an easy one - .020" undersize bearings. But, the mains have no such numbers. Just FM2227 SB. So, I assume FM is for Federal Mogul. I can't find a listing for that number in any database. I had originally thought that maybe the "SB" stood for standard bearing?" But, now, I'm not sure. Bearings looked good and I was just going to reuse them - so it didn't matter. But, just checked and they've got .0035" clearance (too much). So now I want new ones and can't figure if they're standard or some undersize that is NOT stamped on the bearing. I can't get a mike onto the crank journal while it's still in the tractor. I did attempt a crude measurement with calipers and tape measure and with this very poor measurement - the crank journal seems to be around 1/32" smaller then standard. That could easily be .020" or .030" under.

So, at this point, I have no idea what bearings go get. Anybody ever come across an undersize main bearing that was not marked undersize?

Click to expand...

Why is .0035 clearance too much? Sounds about right to me.

A FM 2227SB Federal can be any size from a Std to a .060 undersize. The SB stands for the bearing material. (Steel back Babbitt lined) (Cp is a steel back Copper alloy lined with a Tin overplate)The best way to ID the bearing size is with a ball mike. A Std. bearing should measure .093 thickness. at the crown. It will be .0005-.0007tenths thinner at the parting line on each side. A .020 brg would be .103 thick. .010 thicker on each brg. half.
Earl In Illinois

Call Federal Mogul at 1-800-325-8886 this is their tech service number and should be able to tell you which undersize mains you have. Hal

This would tell you real quick.

You could get close enough with calipers to tell if they were standard or over sized.

Of-course the best way would be to mic both the crankshaft and bearings.

Bearing shell when miked at the end is .13" thick, so I'm still not 100% confident. That does not go along with the thickness specs you gave, if this thing is .010" as it now seems.

I also pulled out both halves of the thrust, held them together and put an inside mike in. Came up with 2.24" best I can tell. Standard crank journal is 2.25" So, that seems to put me in the ball-park of .010" under. But thickness, by what you stated puts it at .020".

At this point, I'm tempted to just throw it back together as is. Front journal by the oil pump checks a .0035" clearance. Center thrust bearing around .004" clearnace. Haven't checked the rear yet, but the rear and furthest from the pump is often the worst. Factory specs call for a max wear limit at .0037". So, I'm sure it would be OK if that rear main isn't much worse. I just hate to do things "half-a**ed" when I can avoid it. But new bearings are $70-$80 and I'm not even sure what I need.

Did you use a ball micrometer? You need the ball part of the micrometer on the bearing surface. Otherwise a standard micrometer won't give a correct reading. If you don't have a ball mike you can use a new ball brg ,measure it,write it down .Now put the ball on the bearing surface & mike the ball & the bearing . Subtract the ball OD. It should give you the correct bearing thickness within .0005 tenths. The bearing spec I gave you came out of the FM brg manual.

The measurement of the actual bearing shell thickness I did with a standard 1" mike. And because the tips aren't rounded, I only checked on the very edge of the bearing shell and edge of the mike surface due the curve. I understand the edge/end of the shell is supposed to be a little thinner (maybe .0005" or something). That should of gotten me at least a ball-park measurement. That was .13"

The other measurement - with two bearing halves clamped together, was done with an inside mike. Did it with the thrust bearings which are pretty rigid. That mike has rounded "ball" ends. Got an ID of 2.24". Standard crank journal is supposed to ge 2.25" That's what has me thinking it's a .010" undersize?

Thanks for your reply and specs. I wasn't even sure the Fm was Federal Mogul. Big "F" and small "m" I checked a Federal Mogul database and came up with nothing. Do you have an old database/catalog?

Not that this will help, but I feel your pain after what I went through with my Ford 9000. The rods were marked 20 under but the mains appeared to be original but didn't match up with any part numbers in the book. Between red, blue and all of the options in the book I was stumped. Finally I ordered original and used a lot of plasti-gage and they turned out to be right.

Yes I had Automotive & AG. machine shop for 30 yrs .1957-87. I have brg manuals that go back into the 50's. & they cover back into the 30's.We were a full service shop. With the 2 brg. halves together the outside should measure 2.437.I would think your 0-1 in mike should be closer to the spec than the .130. Keep trying you can whip it. Remember its man made. Earl

I measure a drill bit shank along with bearing shell and subtract the drill bit. That will get me very close.

Yes Duner, that would work good as long as its nice and smooth no nicks.LOL Sometimes we have to substitute when we don't have the exact tool we need. Starret used to make a little ball tip that snapped over the anvil end of a Starrett 0-1 inch micrometer. Saves buying another micrometer.

Curosity got the best of me. J&L Industrial Supply has the ball tip listed in their catalog.

Well I have Starrett so will look into it. Thanks.

I think I figured out what my bearings are. Part of my confusion seems to be some incorrect information I got from a machine shop.

I clamped my two thrust bearing halves together and brought them down to a machine shop. I did that since I don't have a good inside mike, just outside. So, when I measure, I use inside calipers then re-measuse with an outiside mike.

So, went to the machine shop. The guy laughed a little at me having such a problem that was so "simple." He measured with his inside mike ad told me the bearing ID is 2.24". OK. The standard crank journal is 2.25. He said my bearings are .010" under. I then asked how clearance figures in, and he said his measurements are probably just off by a little.
So, I did not feel comfortable with his "expert" measurement since it did not conincide with my bearing shell thickness measurements.

So, after thinking about many comments made here, this is what I did.

I searched through my big engine manual (not the shorter ITT). Found specs. for main bearing bore in the main saddles.

Bearing mount ID is: 2.437"
Standard crank journal is: 2.250"

Now, I'm no math wiz, but I figured the following.
Space between bearing mount and standard journal is .187". Subtract .002" for clearnace and that comes to .185" Then split in half (thickness of each bearing half) and I get .0925" thickness for a standard bearing. Exactly what Earl-IL stated.

I took a ball bearing and miked it at: .311"

I used the ball against the inside of the bearing shell along with a 1" outside mike. Got a measurement of .413".

So, subtract the ball ID from the total and I get .102" bearing shell thickness.

Going by bearing mount ID versus standard journal, and allowing .002" clearance, I come up with these specs for thickness of bearing shells:

.010" undersize - .0975" thick
.020" undersize - .1025" thick
.030" undersize - .1075" thick
.040" undersize - .1175" thick

So, at this point I am going to assume that my crankshaft if .020 undersize and the machine shop screwed up. So much for hiring "professionals."
And, if I find out I'm wrong, well . . at least I don't claim to be a machinist. Just a grease-monkey.