Rod bearing question

[Case1951]

I have rod bearings that are marked 9785 sb

No other numbers I can find and I tried to order more bearings based on the 9785 sb, but I'm going to measure to be 100% certain anyway now

My helper says "sb" means standard bearing more than likely. We plan to measure the journals this weekend to be certain. But now I'm wondering, does the "sb" usually mean it had standard rod bearings? Wouldn't oversize bearings usually be stamped with a number? Thanks

 

[kencombs]

I don't know the answer to the sb question, but if we knew the brand, maybe someone could access the parts catalog for that brand?

 

[Janicholson]

With respect, mains and rod bearings are undersized but thicker than OEM. Almost all that are supplied for reground cranks are marked with that undersize stamped in the shell. So it it likely that they are original journal sized shells. To be sure, (and if the crank will remain as is) measure the thickness from outside to inside of the new ones compared to the old ones. Measure near, but not at the parting line to avoid the most wear. The difference will be measured in radius of change. For instance if it is a .020 undersized bearing the thickness will be .010 different. Jim

 

[TerryfromSWIowa]

Bearings are built with eccentricity from center line to near the part line. Meaning they are thinner at the parting line than at centerline. Then there is a relief at the part line they used to call a mud pocket. Eccentricity might be anywhere from .0001 to .001.

 

[henry J]

9785 SB is a Federal mogul bearing #

 

[teddy52food]

If I remember right, it has been a while, the sb refers to the thickness of the babbit.

 

[Fritz Maurer]

Bearings are built with eccentricity from center line to near the part line. Meaning they are thinner at the parting line than at centerline. Then there is a relief at the part line they used to call a mud pocket. Eccentricity might be anywhere from .0001 to .001.

Like to hear more about specific bearings with this feature. For what reason are they eccentric?

 

[TerryfromSWIowa]

Like to hear more about specific bearings with this feature. For what reason are they eccentric?

For oiling, spreads the fluid film around the crankshaft. Look at a worn bearing the load is around 45° either side of the centerline.

 

[Case1951]

9785 SB is a Federal mogul bearing #

It is federal mogul.
Here's how it's stamped exactly- FM 80 9785 SB
I plan to measure later today to be exact

 

[Fritz Maurer]

For oiling, spreads the fluid film around the crankshaft. Look at a worn bearing the load is around 45° either side of the centerline.

I do remember seeing this.... did all bearing companies engage in this elliptical process?

 

[stevieb49829]

Like to hear more about specific bearings with this feature. For what reason are they eccentric?

Fritz, I don't think it is restricted to specific bearings, if that is your question. Most modern engines will have insert bearings with that same eccentric geometry, for the reasons Terry mentions. There's all kinds of videos and stuff on the net about the theory behind the geometry. Most of the engineering came out of people trying to keep high rev race engines alive and well, so there may be some OEM applications where that geometry is not necessary. steve

 

[stevieb49829]

It is federal mogul.
Here's how it's stamped exactly- FM 80 9785 SB
I plan to measure later today to be exact

I would bet on that being a std bearing insert. We will watch to see if your measurements come to that conclusion. steve

 

[T.R.K.]

From 1963 Federal-Mogul shop spec. manual: SB =steel backed babbit. SB is the material it is made of, not 'standard bearing'. This material or construction was real common in the '30s and 40s.
I am thinking if it is undersize it should be marked on the shells and on the box, if it is still present.
They fit MM engines in (early) RT, and ZT tractors. Rod bearings.

 

[teddy52food]

From 1963 Federal-Mogul shop spec. manual: SB =steel backed babbit. SB is the material it is made of, not 'standard bearing'. This material or construction was real common in the '30s and 40s.
I am thinking if it is undersize it should be marked on the shells and on the box, if it is still present.
They fit MM engines in (early) RT, and ZT tractors. Rod bearings.

I was close! I knew it had something to do with the babbit & not the size.