Babbitt Bearings

[Logan]

Our longest babbit life has been 25k so far with the bearings being tightened up just once. Our worst one has been 150 miles before center main was gone. We also had 2 other babbit jobs fail under 1000 miles. And yes we do proper break in periods. The new engines were all driven 40 mph. After the three that failed within 2k miles we switched to inserts and will never go back to babbit.

[Kohnke Rebabbitting]

Originally Posted by Bob Johnson

Here is a picture of a main cap. The measurement of 1.593" indicates that this cap is for a 0.030" undersized crank journal (1.625 - .030 = 1.595). The measurement of 1.732" is the horizontal size of the inside of the cap without the babbitt. Thus the babbit would be about 0.070" thick for the 0.030" undersized crank. Or about 0.055" for a standard size crank journal.

Another interesting thing is if you take the height of the bore without the babbitt, 0.864" and double it you get a number 1.728" which is 0.004" smaller than the width of the bore 1.732".

Now add a shim pack that is 0.032" thick. The thickness of the babbitt will not change at the area where the cap meets the block. But the babbitt thickness at the top of the cap will now be 0.070" + 0.028" (0.030" - 0.004") = 0.098" which is almost twice the thickness of what it was in a new engine (0.055").

Of course this is only an example of just ONE cap. It would be interesting to see what the variation is with other caps.

Bob

There are some caps that have been filed so much, that we had to pitch them. So Bob, what would be your conclusion to your post, and or your hypothesis. Thanks Herm.

[Kohnke Rebabbitting]

Originally Posted by Logan

Our longest babbit life has been 25k so far with the bearings being tightened up just once. Our worst one has been 150 miles before center main was gone. We also had 2 other babbit jobs fail under 1000 miles. And yes we do proper break in periods. The new engines were all driven 40 mph. After the three that failed within 2k miles we switched to inserts and will never go back to babbit.

You can't blame the Babbitt, it doesn't take much to know where the blame lies. I had bearings in the Blue Plymouth Coupe, car No. 42 in the China to Paris race, and it didn't have any bearing trouble, and in all had about 10,11 K. on, and very hard miles. Its a good thing that the guy that put in your inserts, knew what he was doing, as your choices are about dried up. Thanks Herm.

[pooch]

Are you saying that a bad insert job means the block is scrap?

But a bad babbitt job can be salvaged?

[Kurt in NJ]

Bad babbitt can always be chopped out and new babbitt poured, many times when an insert fails the bore (block) is damaged --and the crankshaft---then you need to look for a different insert that is for a larger outside bore,yet still has the proper inside bore and have the crank ground, or replaced.

A modern engine with inserts that has a spun main usually will have the block and crank replaced ---or $$ machine work.

A babbitt engine with a failed main many times just needs the babbitt replaced.

An insert is easier to replace if it is caught before failure.

I have had 2 babbitt failures, the rear main, and a rod, both failures did no crankshaft damage. The babbitt I paid to have done failed, gave me the courage to do it myself--so far that has lasted 4x the what the professional job did, and I have tried to break it.

Done properly both inserts and babbitt will work for very long times, babbitt can always be redone, but with inserts you have to hope whatever inserts that were used can be found in the size you need.

[George Miller]

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I had a 1930 Townsedan it had 80,000 miles on the original engine, never been rebuilt. Babbitt was very good. The rings were getting bad.

[deuce295]

I have read a lot of discussions about the thickness of shim packs available today and I am just curious as to the ability to just make your own shims. Couldn't you just get some .003 shim stock and fabricate your own shims possibly using steel shim stock to get away from the softer brass type availble now? Just curious.

[redmodelt]

Another thing to consider, what kind of babbitt was used? High tin(correct) or high lead(wrong).

[brum1]

Brian,

Was the engine knocking with the bearings in this condition? Also, what did the oil look like on the dip stick-where there bits of babbitt?

[Kohnke Rebabbitting]

Originally Posted by Kurt in NJ

Bad babbitt can always be chopped out and new babbitt poured, many times when an insert fails the bore (block) is damaged --and the crankshaft---then you need to look for a different insert that is for a larger outside bore,yet still has the proper inside bore and have the crank ground, or replaced.

A modern engine with inserts that has a spun main usually will have the block and crank replaced ---or $$ machine work.

A babbitt engine with a failed main many times just needs the babbitt replaced.

An insert is easier to replace if it is caught before failure.

I have had 2 babbitt failures, the rear main, and a rod, both failures did no crankshaft damage. The babbitt I paid to have done failed, gave me the courage to do it myself--so far that has lasted 4x the what the professional job did, and I have tried to break it.

Done properly both inserts and babbitt will work for very long times, babbitt can always be redone, but with inserts you have to hope whatever inserts that were used can be found in the size you need.

Very good Kurt, Herm.

[Kohnke Rebabbitting]

.

Originally Posted by deuce295

I have read a lot of discussions about the thickness of shim packs available today and I am just curious as to the ability to just make your own shims. Couldn't you just get some .003 shim stock and fabricate your own shims possibly using steel shim stock to get away from the softer brass type availble now? Just curious.

Do NOT use steel, as Steel shims have No Place around a Babbitt, or any other type of bearing. The only time, and that was once, I have ever seen steel shims in a Model A was a mix, of steel, and brass, and it wasn't factory. Ya, YA, I know that there were steel shims in Ford packages, but by the packages I seen at swap meets, they were replacement parts long after the production of the Model A, probably even the 40's, and 50's. You would think, of all the scrap shims we have had, you would think we would have a 50 gallon barrel for steel, as well as brass, But NO. Now 99.9.9 percent of all rods, and mains we rebuild have brass shims, and that is what they had right from the factory. Steel shims were available, the Laminated sheets are today. What ever steels shims were used, it was for saving money, cheap, cheap, cheap. All John Deere have 1/8, or 3/16 shim packs, ((TWO CYLINDERS )).032 thousands of Brass, and the rest of the pack is a steel filler plate to make up the difference. All the whole shim pack misses the crank by about .015 to.020 thousands. A Model A you have to have the shim pack pushed right up to the crank, to keep as much oil in as you can. Now here is the BAD PART, NO.1, Steel, against steel, NEVER WORKS, steel will eat at a shaft, ((and CAN BE MAGNETIC, not good at all)) it will tear off microscopic pieces, and embed it self in the babbitt, and can groove the shaft. Brass seams to wear off, or if there is a chip, it will embed in the babbitt and wear as the bearing, with out grooving. I have put alot of Model cam bearings in, made out of Brass stock, ever wonder why there not made of steel. Cast block is good, but not steel. Just Common sense. The last thing on steel shims, 75 percent of the time we Align Bore the shims along with the Rods, and, or mains. With the cutter sharpened correctly you can bore bearings, and mains with the brass sticking out, as any gap will let oil out fast with a pressure system. If you tried to do that with a steel shim,(( ALWAYS, NO EXCEPTION )) you instantly pick a Steel shaving on the end of the cutter, and as your boring , the babbitt really gets tore up. I learned that 40 some years ago, anyboby care to guess how. Thanks Herm.

[Kohnke Rebabbitting]

Originally Posted by deuce295

I have read a lot of discussions about the thickness of shim packs available today and I am just curious as to the ability to just make your own shims. Couldn't you just get some .003 shim stock and fabricate your own shims possibly using steel shim stock to get away from the softer brass type availble now? Just curious.

You can get any shim stock today, that was available in 1920. You can get any babbitt recipe that was available in 1920. they did not use steel shims. Thick babbitt is much stronger then thin babbitt, in cases where it can't be tinned. Babbitt failure, if not oil, or abuse, is not a multiple choice answer. It is the Babitter, Babbiter, Babitter. There are many shops that bought K.R.Wilson Babbitt tools, and right away they thought they were a Rebabbitter, and that includes me, even at 15. What bothers me is, some day, this profession will be gone, and the know how, as it is regarded as some kind of secret, and if there is any body left that does know how, they can name there price. I rebabbitt for one large shop, that puts inserts in some old rods, and they work fine, but the owner said they are already having trouble some replacements, as they go obsolete with out warning. As one of the guys said on here, his car has 80,000 and I am not surprised at all. Yes I know that most model A's have given up before that, but during the depression years, as I don't think any body changed ther oil much. But if you are getting 100, to a thousand miles, and the babbitt fell out, you chose your rebuilder unwisely. It would be hard to explain the block rebabbitting process, but there is only one way that will work, and no more. On rods, Inserts, and other rebabbitting, it is always a job with many variables, you just have to recognize the difference. Herm.

[deuce295]

Thanks for the input on shims Herm. I really had no idea that the alignboring was done and actually cut any shim overhang. Makes sense though. I know I have taken a motor apart and it did seem to have a mix of some brass and some steel. Obviously not real well put together. I enjoyed your response and learned something so thats all good.

[Larry Brumfield]

Originally Posted by Kohnke Rebabbitting

Thick babbitt is much stronger then thin babbitt, in cases where it can't be tinned. Babbitt failure, if not oil, or abuse, is not a multiple choice answer. Herm.

Hello Kohnke. I see you're still singing the babbitt tunes.

You've seen a variety of engines go through your shop.

What in your opinion would be the longevity of thick babbitt bearings, the thicker the better, if they were used to replace the inserts in an engine like in my 70 Vette ... with 11.25 to 1 compression ratio, 460 horsepower and 490 ft.-lbs. of torque?

[gilitos]

"Thick babbitt is much stronger than thin in cases where it can't be tinned." Read this statement carefully, this is absolutely true and doesn't obviate your point at all, Larry. Explanation: If the cast iron isn't tinned and adhesion is poor, the babbitt can't transfer stress to the saddles. If tinning is done properly and adhesion of the babbitt is excellent, then stress on the bearings is transferred to the saddles, which reinforce the babbitt. Perfect analogy is a composite material like fiber-reinforced epoxy: if the fibers adhere well to the resin, they reinforce it and the strength is excellent. If they don't adhere well to the resin, then no stress can be shared by the fibers and the strength can be lower than with no fibers present. Rigid, strong fiber = iron bearing saddles; softer, weaker epoxy matrix = babbitt. Adhesion is absolutely critical, and proper tinning is only way to get it.

In cases where adhesion is excellent (read: properly tinned), thin babbitt will be stronger. Insert bearings: great adhesion allows thin babbitt to share strength and stiffness of steel shell backing. If thin babbitt in an insert bearing adhered poorly, the bearing would last about 1 revolution. But thick babbitt, adhering poorly, can last 1000's of miles (but maybe not much longer!).

Kindest regards and loving this sort of discussion,

Giles

[Kohnke Rebabbitting]

Originally Posted by Larry Brumfield

Hello Kohnke. I see you're still singing the babbitt tunes.

You've seen a variety of engines go through your shop.

What in your opinion would be the longevity of thick babbitt bearings, the thicker the better, if they were used to replace the inserts in an engine like in my 70 Vette ... with 11.25 to 1 compression ratio, 460 horsepower and 490 ft.-lbs. of torque?

I don't Know, what in your opinion would be the longevity of two of your Model A heads in your 70 Vette--- with 11.25 to 1 compression ratio, 460 horsepower and 490 ft.--lbs. of torque, even if you could get all of your spark plugs actually screwed in. Oh, Ya, Model T block, with babbitt, and ether a RAJO, or Gallivan, with duel over overhead ( thats means cams brumy) ran 14 to 1 compression, no Bearing problems. Thanks Brumy, Kohnke.

[Larry Brumfield]

Originally Posted by Kohnke Rebabbitting

I don't Know. Thanks Brumy, Kohnke.

That's what I thought.

Thanks Herm.

[Larry Brumfield]

Originally Posted by gilitos

"Thick babbitt is much stronger than thin in cases where it can't be tinned." Read this statement carefully, this is absolutely true and doesn't obviate your point at all, Larry.
In cases where adhesion is excellent (read: properly tinned), thin babbitt will be stronger. Insert bearings: great adhesion allows thin babbitt to share strength and stiffness of steel shell backing. If thin babbitt in an insert bearing adhered poorly, the bearing would last about 1 revolution. But thick babbitt, adhering poorly, can last 1000's of miles (but maybe not much longer!). Giles

Thanks for your input, Giles. However, I don't care for thick babbitt even though it will work on a Model A. Pete, below, from another thread put it in words better than myself:

Originally Posted by Pete

"In my opinion, the thinner the babbitt the stronger and the thicker the softer. Now depending on the differences it may not be greatly significant in all cases or even be a problem but it's still there." (Larry Brumfield)

I just happened across this thread so I guess I missed most of the fun.

Larry is right according to the laws of physics. That is one reason modern shell bearings only have babbit .0002 thick.

Actually a given bearing material will deflect at the same RATE for different thicknesses but the thicker one will deflect farther with the same load thus causing more movement in the total assembly..This movement caused by the reciprocating forces equates to less bearing life.

The bearings in a model A engine are so lightly loaded that almost any thickness would work though.

.

[Kohnke Rebabbitting]

Originally Posted by gilitos

"Thick babbitt is much stronger than thin in cases where it can't be tinned." Read this statement carefully, this is absolutely true and doesn't obviate your point at all, Larry. Explanation: If the cast iron isn't tinned and adhesion is poor, the babbitt can't transfer stress to the saddles. If tinning is done properly and adhesion of the babbitt is excellent, then stress on the bearings is transferred to the saddles, which reinforce the babbitt. Perfect analogy is a composite material like fiber-reinforced epoxy: if the fibers adhere well to the resin, they reinforce it and the strength is excellent. If they don't adhere well to the resin, then no stress can be shared by the fibers and the strength can be lower than with no fibers present. Rigid, strong fiber = iron bearing saddles; softer, weaker epoxy matrix = babbitt. Adhesion is absolutely critical, and proper tinning is only way to get it.

In cases where adhesion is excellent (read: properly tinned), thin babbitt will be stronger. Insert bearings: great adhesion allows thin babbitt to share strength and stiffness of steel shell backing. If thin babbitt in an insert bearing adhered poorly, the bearing would last about 1 revolution. But thick babbitt, adhering poorly, can last 1000's of miles (but maybe not much longer!).

Kindest regards and loving this sort of discussion,

Giles

You got it Giles, the only reason .010, or .020 is to thin in cast A Block, is even if peened right, when very hot, pounding will fracture the babbitt,(( because, it is not stuck, you have movement, a killer)) much faster then thick babbitt, because you don't have strength in material. If you do not peen right, or as in many cases, not at all, the crank will do the job for you, as the babbitt when cooled, deflected away from the block, and when the crank does it cold, it brakes up. The tinned bearings, say a Brass shell, babbitt thickness makes no difference what so ever, as it is tinned, that is what holds it, and transfers heat. Its is stuck, so no movement, that thickness normally doesn't go over a 1/2" thick, any bearings over 1/2", is normally solid babbitt, again strength in material, no backing, as I have said we built 35 pound babbitt bearings, and that was just 1/2 of bearing, no backing, that were a machine fit in light plant Diesel rods, that weighted about 200 pounds each, they would last the life of the overhaul. As time has went on from the steamers, the high wheeled tractors, cars ect. they found out they could cut back on the thickness, and save alot of money in babbitt. They found out they didn,t need babbitt on the sides of the rods, but they still have to be straight. All of the 4 cylinder Chevys, had solid babbitt inserts in the block, front, and rear, about the same thickness as the peened in Fords, and only a lug, about 3/8's to hold them in. The blocks were machined, as the babbitt inserts were precision, so it was like a modern insert, so they didn't need peening. We sell about 5 to 10 sets a year. Thanks Giles, Herm.

[James Rogers]

Originally Posted by gilitos

"Thick babbitt is much stronger than thin in cases where it can't be tinned." Read this statement carefully, this is absolutely true and doesn't obviate your point at all, Larry. Explanation: If the cast iron isn't tinned and adhesion is poor, the babbitt can't transfer stress to the saddles. If tinning is done properly and adhesion of the babbitt is excellent, then stress on the bearings is transferred to the saddles, which reinforce the babbitt. Perfect analogy is a composite material like fiber-reinforced epoxy: if the fibers adhere well to the resin, they reinforce it and the strength is excellent. If they don't adhere well to the resin, then no stress can be shared by the fibers and the strength can be lower than with no fibers present. Rigid, strong fiber = iron bearing saddles; softer, weaker epoxy matrix = babbitt. Adhesion is absolutely critical, and proper tinning is only way to get it.

In cases where adhesion is excellent (read: properly tinned), thin babbitt will be stronger. Insert bearings: great adhesion allows thin babbitt to share strength and stiffness of steel shell backing. If thin babbitt in an insert bearing adhered poorly, the bearing would last about 1 revolution. But thick babbitt, adhering poorly, can last 1000's of miles (but maybe not much longer!).

Kindest regards and loving this sort of discussion,

Giles

And cast iron CANNOT be tinned, EVER.