Bearings babbitt or Brass

[Guest Rick001]

I'm putting together a 1908 buick model 10. Is there any reason why I can't machine my own brass bearings as opposed to having babbitt poured. If not, does anyone know why? Strength, longevity, etc. I would appreciate your response.

Thanking you in advance for your expertise. Rick

[Guest carlnut50]

I believe brass is too hard for the crankshaft main bearings. If you can machine brass bearings you can machine a mandrel and collars so you can pour your own babbit. I would not take a chance in ruining the crankshaft on such a rare valuable car.

[Packard enthus.]

brass is considerably harder than "babbit". "Babbit" is a general term for various "mixes" of lead, tin, and, depending on how durable you want the bearing to be, other metals such as copper or aluminum.

My concern, is that brass would have too high a "surface friction" with your crank-pin surface, wear rapidly, perhaps even over-heat and burn out.

Since I do not think I alone have all the answers to automotive engineering issues, I tend to "go with the flow" of COMPETENT automotive engineering technical journals ( I know..I know...why read the SAE technical papers when Joe Six Pack is around to tell you how much more he knows about engine bearings, than automotive engineers)....

Anyway, while I normally have a fit if I hear of anyone trying to use babbit in a post "antique era' car...in your case, given the VERY low rpm, light use, and light crank-pin "loadings", I would probably put babbit back in there.

Given the VERY low rpm REAL antique car motors run at (for those who think a car built after around 1920, when cars started to get balloon tires, four wheen INTERNAL EXPANDING brakes, and on-board battery-generator electrical systems, are "antiques"...well....have a nice day...!

[oldiron]

The question you need to ask yourself Rick, is not why you can't use brass instead of babbit, but, rather, can you afford to replace your crankshaft if something goes wrong.(Consider that the coefficient of friction is reliant on the fineness of the surface and not necessarrily the material that the bearing is made of; but also that the oil, as the lubricant, separates the surface of the journal from the bearing shell,thus taking the various metals coefficients of friction out of the discussion when oil is present. When oil is not present, then the problem arises as to the considerations of coefficient's of friction of the materials, and as to their strengths.). Here's the point as to why babbit is considered over brass/bronze. If oil is kept from being delivered to the bearings, the brass will do much more harm to the journals than the babbit, what with the galling and surface tearing thats done with the build up of heat due to lacvk of lubrication. The babbit will be torn up before the crank journal when lubrication is taken away in this instance. And, so what can happen to the crankshaft is the main concern, not why you can't use one material over the other. I restored a Model F Buick severasl years ago and machined my own bearing shells from brass. But, understand that motor's lubrication is supplied by an oiler, and not by splash. Also it is a lower RPM motor, a two cylinder job, and not much damage will be done if the oil stops flowing. It should slow down as it overheats from lack of lubrication, and stop. Upon cooling off, it should restart and run fine. A four cylinder is a different story, as it is a higher RPM motor, and has different needs. Finally, why not use babbit anyway. Just get some help on the pouring part of it, and then do the line boring yourself if that's what you'd like. Regards; oldiron

[Jay Wolf]

Rick

I had a 1916 Elgin 6 with shell (not poured) babbit bearings.

The front main cap (of 3 mains)was broken and 1/2 of it missing when I got the car. So I didn't have a insert or the bearing to make a mold from.

I had a new cap machined and the guy made me bearing out of oil impregnated brass bearing material. I never had a bit of problems with it.

Babbit wasn't a choice for me since they were shell and I had nothing to make a mold out of.

The owners manual gave great bearing adjustment instructions.

"Grasp the crank with your hand if you can move it up and down, remove shims till it will not move.

If you can not hand crank it by hand add shims back in."

After about 100 mile (recommended bearing check as per manual)

I pulled the pan and everything was fine no problems no adjustment needed.

[Guest EMF-Owner]

This is an interesting question and a topic I have wanted to ask about also. My Father is planning to rebuilt his 1909 Sears engine using Nickel Bronze instead of the Babbitt inserts it had originally. We have went around and around about this with me bringing up many of the points already discussed here. His argument is that he has successfully done this many times in his career as a machinist for the railroad. He also replaced the Babbitt bearings in his 1926 Ingersoll-Rand Air Compressor with Nickel-Bronze 30 years ago and we have run that engine many many hours.

So would nickel-Bronze make a better choice for bearing stock?

I look forward to hearing more about this.

Oh, and just to note, I doubt any of the discussion would persuade him to change his mind. He is very stubborn. Guess I know where I get it from. <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

John

[Packard enthus.]

What a novel idea - NICKEL impregnated bronze. Bet that would work just fine in your particular application.

Yes, I do make fun of the "Joe Six Pack" types who come in here and all have a better idea than the tens of thousands of legit. mechanical engineers, and the technical papers they write, who all came to the same conclusion, now universal in the automotive internal combustion industry i.e. "precision" steel "shell" or "insert" type con. rod bearings.

But every once in a while, one of us shade-tree wrench turners comes up with something that would work in a unique application. CONGRADS ! GREAT IDEA>

[Mark Shaw]

I got this from the Internet (author unknown) & condensed it for you:

Babbitt is a tin based alloy bearing material with two other primary elements; copper and antimony. Originally, Babbitt did not have ANY lead in it. But the name "Babbitt" soon became the generic name for any bearing material, & lead based bearing materials are now included in the term Babbitt.

Tin is a great metal for a bearing. It is soft, but not too soft. It will let dirt embed and it coats it so it will not score the shaft. If you run out of lubricant, the tin will melt some and liquid tin is a lubricant too. But it really is too soft to be used alone as a bearing in engines as it melts at too low a temperature (449* F)

Copper is used to make the tin harder. As the percentage of copper increases so does the melting point of the tin copper alloy. Copper melts at 1984* F.

Antimony also makes tin harder and increases its melting point. Antimony brings another unique property it shares with water. Antimony expands as it solidifies. Most metal shrinks as it cools. Shrinking means the bearing that was just poured will pull away from the block. Antimony melts at 1167* F.

Copper and antimony also affect the malleability of the alloy. They modify the proprieties of the tin and allow it to handle the impact force in the engine without cracking or become squished out like butter.

Draw your own conclusions, but for my money, tin Babbitt is the way to go. It is a good bearing material and will protect your crankshaft from being worn or scored.

[A by the sea]

First some stuff on babbitt.

Babbitt (not lead based bearing material) is kind of special in its properties. The tin is your main bearing material with the copper and antimony giving hardness and impact resistance and some other characteristics. The tin is fairly soft and allows dirt to embed into it safely. This prevents the crank's bearing surface from being damaged. The tin will also act as a lubricant if gets warm enough such as a no oil situation or just high spots wearing down.

If you put in brass than you will be increasing the wear on the crank since now the dirt has no place to go and the brass is harder.

Lead based bearing materials, also called babbitt these days, are a poor choice for engines. Lead work hardens and cracks easy with the pounding put on by the normal cycle of the IC engine. To make lead harder some are mixed with nickel and the nickel crystals are hard and sharp and will wear the crank. Lead is good for things that just spin like table saws.

Babbitt comes in different hardnesses and generally the softer the babbitt the easier it is to pour as you pour at a lower temp. You have to be careful in you babbitt selection, how thick will the babbitt be? The harder stuff is designed to fairly thin or it will crack easier in use.

You need to talk to a shop experienced in babbitt pouring in the old engines. You have other considerations. How much will you actually run the engine? If you only plan on putting 10 miles a year on the car then just about any bearing will probably last the life of the car. If you really plan on driving the car then you need it done right. You also need to consider the material the crank is made out of. The model A crank was hardened to a certain point, but could be left fairly soft since it road in babbitt. Your crank is not likely to be very hard and if it was surfaced hardened did the machining remove the hardness?

There is a lot of science to babbitt. If a guy says he thinks one thing will work but can not explain about babbitt and its properties than I would question his abilities.

I wrote up some technical stuff on babbitt based on technical documents and how it relates to the Model A Ford, here is the link.

Babbitt

[Guest Silverghost]

There are some very good posts on Babbitt bearings here...

Here's what I can add about lead..

Re: Lead in bearing material or "Pot Metal" die castings...

Small amounts of lead in poured bearings should not allowed!

It was discoverd in the 40s that even very small amounts of lead can cause what is called intergranular corrosion!

This is true of bearings or "Pot Metal" die castings.

How many times have we all seen old "Pot Metal" die castings that are swelling , cracking and crumble... It was found that small amounts of lead caused Intergranular corrosion. The mixture was self-destrusting.

By removing all trace lead modern die castings can last for many many years.

Modern bearings and poured babbitt should contain no lead...

In the past any small amounts of lead caused these bearings to crack and crumble. Add the acids in older oils and from the combustion process and the problem gets worse...

Older poured bearings also get work hardened with age, use, and high speed pounding...

This makes them subject to cracking...

Modern poured babbitt is far better than the old alloys used from 1900-1940...

Do not be afraid to have any old beaings re-poured with modern bearing alloys.

You will be very glad you did!

[Guest Silverghost]

6686L...For Your Information I AM in fact a Mechanical Engineer! B.S. Drexel University 1976/ M.S. University. Of Pennsylvania 1978...

ASME life member...

Where did you get YOUR Engineering Degree?

Folks we are talking a 1908 Buick here...

This is a very simple slow running engine of very simple design, low horsepower, with no pressure type lubrication system...

A good babbitt bearing job should last way beyond our lifetimes...The "modern" babbitt mixtures are far more stable and do not contain very high trace levels of lead, if any at all, which can in fact lead to intergranular corrosion and bearing self-destruction!

This happens over time at the microscopic grain level.

We have all seen rotten "Pot Metal" which cracks, swells, and crumbles...

Later larger engines can possibly benefit from insert-shell bearings...especially if run at 55-60 MPH highway speeds...Shell inserts can handle the stresses of high speed pounding much better than babbitt & are much easier to replace in future rebuilds...

BUT...

I have seen far too many botched shell machining jobs that have all but ruined blocks,rods, crankcases...

I really see no reason to install shell insert type bearings in this early 1908 Buick application...In fact it might cost you less in te end.

Bronze or oilite bronze bearings would not work well in this application. The Bronze would in fact over time wear & abrade the crankshaft...

Remember...there is no pressure lubrication system on this engine...Babbitt can handle this early splash & drip oiling, and total loss type lurication much much better!

In a pressure type oiling system you are always riding on a thin film of oil with no real metal to metal contact...

Not so on a total loss, drip, or splash type oiling system.

Bronze will wear iron or steel crankshafts

This goes against everyone's thinking...Bronze is softer than iron or steel...so most think it should not scratch steel or iron... but in fact it will abrade it badly.

Poured babbitt type bearings have been around for close to 200 years...they work very well in older "Antique" car gas & steam and hit/miss engines...They can tolerate older simple non pressure type oiling systems and keep running for many many years...with the use of shims wear can be delt with very well long term.

In the end...it's the car owner's choice!

[Packard enthus.]

I want to apologize to Brad for my sarcastic (and now deleted) response to his comments about connecting rod bearings. Brad is correct, IF he is limiting his response to acceptable shop practices to engines of the pre 1920's era.

As Brad notes, on these very VERY slow turning small crank-pin "T" head type engines, re-pouring originally poured babbit rod bearings most certainly IS an acceptable shop proceedure.

My criticism of Brad's excellent comments, should have been clearer - for that I again apologize. I should have made the distinction between the fellow with the '08 Buick, and the MUCH higher r.p.m. engines of the twenties and later.

I personally believe there is NO excuse for not spending the extra effort to install "insert" type rod bearing shells. Again, once we get into the more modern higher rotating speed engines of the 20's and later.

As I noted in my numerous "posts" repeatedly, elsewhere in these forums, except for Buick and Chevrolet, the industry abandoned the "poured babbet" concept by the mid 1930's. And for good reason. As Brad notes, once we start spinning engines faster than the old "antiques" ( here, using the word "antique" in its traditional manner, meaning the old slow turning engines of before, oh, say around 1918) "insert/precision shell" type rod bearings are, in my view, the only legit. alternative.

And, as I noted in another thread, Brad is absolutely right that sub-standard machine work in trying to adapt a modern "insert" type bearing into an old connecting rod that was initially "poured", most certainly WILL result in disaster. And the sad fact is, I have seen many examples supporting Brad's view - which result in disappointed car buffs abandoning our hobby.

I noted elsewhere the tragedy of trying to drive cars with "poured babbit" connecting rod bearings (again, now referring to cars of the late 1920's and later) - underscored in the newspaper articles covering the opening of the Penn. Turnpike in 1938. Rod bearing failure owing to the inadequacy of the poured babbit concept became an epidemic as a result of the faster speeds the roads of the 1930's permitted.

Virtually NO manufacturer of automotive, marine, aviation, etc. motors is using the old "poured babbit" concept today, even tho it costs much more in machinery and labor time to make a connecting rod bearing using the precision shells.

The fellow with the '08 Buick will do well to listen to Brad's excellent advice. There are a number of quality restorers of antique engines (again, using the word "antique" in its correct techncial definition - applying to cars built before the 1920's) who can perform the service of re-pouring connecting rods of that era.