# Engine bearings material?



## Robert Simons (Feb 23, 2022)

Hi guys.
Wanting advise on what material would be best to make split big end, and mains bearings from.

Looking at either aluminium, or Brass. Both plentiful in stock..
Am building a 1/4 scale ford Flathead, with a solid steel crank.( already turned and polishied, but not yet profiled or balanced).
It will have a pressurised oil system.
Block to be aluminium with sleeves..

I know that bronse would be best, but have heard aluminium is used for commercial bearings...
Your thoughts gents?


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## stevehuckss396 (Mar 6, 2022)

Sorry for the late reply. I use bronze for mine. Works great


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## SmithDoor (Mar 7, 2022)

I agree with bronze
Lead is also used in pass. 
Today I see a lot ball bearings used today.  
Aluminum is used on cheap engines. 

Dave 



Robert Simons said:


> Hi guys.
> Wanting advise on what material would be best to make split big end, and mains bearings from.
> 
> Looking at either aluminium, or Brass. Both plentiful in stock..
> ...


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## methuselah1 (Mar 8, 2022)

Aluminium is fine if lubricant is present. The VW beetle originally had the camshaft running directly in the elektron case. It was an inexpensive car, but that cannot be said of the engine. Guess what? The cams used to wear out.

Many modern motorbikes still do the same. Honda, Suzuki, Yamaha. Hardly bargain basement machines.

Many of Westbury's engines give the option of bronze or aluminium con rods, without bearing shells, same for Gerry Howell's V2 and V4 IIRC. Just pick a good grade of aluminium like 7071. An added benefit is that ally is very forgiving with shock loadings... Top fuel dragsters may use bearing shells, but the rods are always aluminium, for this reason.

-Andrew UK


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## mrehmus (Mar 8, 2022)

Zamac ZA-18 and ZA-28 are the alloys I've used. (aluminum/Zinc) is a superior bearing material compared to aluminum. It is 3 X as strong as well and melts at just under 1,000 degrees which makes it easy to cast the bearing halves. It also machines very well.


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## radial1951 (Mar 8, 2022)

SmithDoor said:


> I agree with bronze
> Lead is also used in pass.
> Today I see a lot ball bearings used today.
> Aluminum is used on cheap engines.
> Dave


The Toyota 4.5L V8 Diesel in Landcruisers has aluminium bearing shells for the crankshaft main and conrod big end bearings. Definitely not a cheap engine. I'm sure many other engines are similar. And EVERY car on the road has the gudgeon pin running in the bores in the aluminium pistons. Of course, lubrication must be correctly applied for aluminium bearings to be successful.

Ordinary extruded brass is useless as a bearing metal unless lightly loaded at low speed eg many low cost clocks. In the old days, bearing shells were called "brasses" maybe because they are somewhat like the colour of brass? Perhaps they were cast brass with some additives? Standard brass is a copper-zinc based alloy whereas bronze is copper-tin based with other alloys added to improve various qualities depending on the application.

There are many varieties of bronze for bearing applications. Ordinary phosphor bronze, gunmetal, leaded bronze, aluminium bronze, nickel bronze etc. Aluminium and nickel bronzes can be difficult to machine. The Bronze Age never really stopped.

If your crankshaft is fully pressure fed, the correct grade of aluminium might be right for the job. Be aware that the slightest failure in oil delivery could be instant bearing death. Phosphor bronze could probably survive a short term lack of oil. Bearing metal survivability will depend on the revs at that instant of course...


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## GreenTwin (Mar 9, 2022)

I worked in a gas station when I was in high school, seems like 100 years ago (1972 to be exact), and several times per year, someone would pullup in a Vega that had low water in the radiator.
The engine was finished, and would barely run, or would sieze up completely on the spot.

Aluminum pistons running on an aluminum cylinder wall as I recall.

I am sure with the right allow, aluminum would work as well in any application, as long as it is lubricated (as someone above mentions).
With a soft alloy, aluminum may not last very long.

The Vega and Pinto were quickly known as the cars to avoild at all cost.
Someone at my high school died in a minor rear-end collision in a Pinto when the fuel tank exploded.  His girlfriend who was in the car died too.

.


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## Charles Lamont (Mar 9, 2022)

'Brasses' usually had a whitemetal (US babbitt) lining.


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## SmithDoor (Mar 9, 2022)

That was the * B & S* engine.
It was a lowest cost engine.
They would replace the bearing with needle bearing and sleeve the cylinder.
The kill switch was just flat bar over the spark plug. Very electrifying at times too.

Dave



GreenTwin said:


> I worked in a gas station when I was in high school, seems like 100 years ago (1972 to be exact), and several times per year, someone would pullup in a Vega that had low water in the radiator.
> The engine was finished, and would barely run, or would sieze up completely on the spot.
> 
> Aluminum pistons running on an aluminum cylinder wall as I recall.
> ...


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## Bentwings (Mar 9, 2022)

SmithDoor said:


> That was the * B & S* engine.
> It was a lowest cost engine.
> They would replace the bearing with needle bearing and sleeve the cylinder.
> The kill switch was just flat bar over the spark plug. Very electrifying at times too.
> ...


almost all small engine use aluminum pistons on missilery liners I YHINK how it is spelled it been around for many years these engines run on 50- 100 to 1 gas oil mixes and just don’t wear out almost always something breaks my so has a large lawn care landscaping business and their small engines run almost continually he says they break couplings or something else before wearing out. My ducted fan model engines ran on heavy loads of nitro and past 20k rpm broken rods or cranks were not uncommon crashes wiped out s few early in their life. Top fuel racers use aluminum pistons and rods. They rarely wear out most likely get destroyed in motor explosions or simply get burned up by excess temps . I agree use one of the new aluminum alloys and good lib system and you will be ok . 
by the way Vegas had silicon alloy blocks that were supposed to be wear resistant but the slightest overheating or lack of proper oil change or wrong oil led to early demise . Subnet actually made special honing stones so you could repair blocks “sorta” they always smoked and used oil but did live a little longer it was a very tedious process requiring magnifying glass to see if the proper metal was removed between silicone particles in the block we put cast iron sleeves in a few but it wasn’t cost effective. Better to take the lost and buy something else ……like a Pinto. LOL. 
byron


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## SmithDoor (Mar 9, 2022)

I had best luck with cast iron engines.
The aluminum did not hold up

Dave 



Bentwings said:


> almost all small engine use aluminum pistons on missilery liners I YHINK how it is spelled it been around for many years these engines run on 50- 100 to 1 gas oil mixes and just don’t wear out almost always something breaks my so has a large lawn care landscaping business and their small engines run almost continually he says they break couplings or something else before wearing out. My ducted fan model engines ran on heavy loads of nitro and past 20k rpm broken rods or cranks were not uncommon crashes wiped out s few early in their life. Top fuel racers use aluminum pistons and rods. They rarely wear out most likely get destroyed in motor explosions or simply get burned up by excess temps . I agree use one of the new aluminum alloys and good lib system and you will be ok .
> by the way Vegas had silicon alloy blocks that were supposed to be wear resistant but the slightest overheating or lack of proper oil change or wrong oil led to early demise . Subnet actually made special honing stones so you could repair blocks “sorta” they always smoked and used oil but did live a little longer it was a very tedious process requiring magnifying glass to see if the proper metal was removed between silicone particles in the block we put cast iron sleeves in a few but it wasn’t cost effective. Better to take the lost and buy something else ……like a Pinto. LOL.
> byron


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## Robert Simons (Mar 10, 2022)

Thanks guys, for your input. Thinking I will try aluminium, as it is easy to work with.
Ensure plenty of lube pressure, and should be sweet.


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## Badhippie (Mar 10, 2022)

The automotive industry for years engines have ran overhead camshafts in the aluminum heads without bearings using the aluminum head itself as the bearing. 
Thanks
Tom


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## Badhippie (Mar 10, 2022)

Also small engines Briggs and Stratton, Kohler
Engines, and other small engines use the big end of the rod without a bearing if it’s a aluminum rod. 
thanks
Tom


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## Bentwings (Mar 10, 2022)

My steamer has brass upper and lower half shell bearings. Possibly you could donsometingvlikevthat at least they would be replaceable. I’d use a fixture to make them. It would not hurt to make a step so they might locate more truemine just depend on very tight tolerance. Bigvyhingbis make sure there is end clearance at either thrust or shoulders. 
byron


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## perko7 (Mar 10, 2022)

ZA-27 zinc alloy has good wearing properties and is easy to cast and machine.


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## SmithDoor (Mar 11, 2022)

The old engines use * Lead Babbitt * for the bearing.
It is easy to use and last a long time.
Aluminum casting are fast and cheap better part of using aluminum casting from manufacturers is when wear out you have to buy a new part.
Lead babbitt any one field can re-poor the bearing. It is temp any can  a gas stove or a camp fire. 🏕.

My self I have on hand for projects is 100 pounds of lead babbitt. But on the other had I also large supply of ball bearing too.
I use what best projects.

Dave



			https://www.maintenance.org/fileSendAction/fcType/0/fcOid/399590942964569365/filePointer/399590942964861960/fodoid/399590942964861958/Fry_Babbitt_Reference_Guide.pdf
		




perko7 said:


> ZA-27 zinc alloy has good wearing properties and is easy to cast and machine.


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## SmithDoor (Mar 11, 2022)

The other part is aluminum/zinc castings the bearing location needs to be replaced.  I do this with brass /bronze bar stock. Cast iron works great to but blanks are harder to come by. Class 25 Cast iron works great for bearing because it more poorest and holds oil better. 

Dave 



perko7 said:


> ZA-27 zinc alloy has good wearing properties and is easy to cast and machine.


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## nanotejarat (Dec 14, 2022)

It depends on the brand. Japanese Bearings such as NTN, NSK, NACHI are made of SUJ2 carbon steel according to Japanese industrial standards. these bearings have the tensile strength of over 1600 N/mm2. 
In general we can classify ball bearings in 2 categories including axial ball bearings which are used less often in industries and radial ball bearings that are the leading type of ball bearings. axial ball bearings are produced only as thrust ball bearings and are meant to be attached on vertical shafts. radial ball bearings are subcategories as deep groove ball bearings, angular contact ball bearings and self-aligned ball bearings.The most common type of ball bearings that is used in almost all kinds of machines is deep groove ball bearing. angular contact ball bearings have smaller rollers and are used more often to suspend loads with high rotational speed. self aligned ball bearings are in fact the most sophisticated type of ball bearing that consist of two rows of rollers and are suitable for machines with high vibration and shaft misalignment.


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## HMEL (Dec 14, 2022)

Robert Simons said:


> Hi guys.
> Wanting advise on what material would be best to make split big end, and mains bearings from.
> 
> Looking at either aluminium, or Brass. Both plentiful in stock..
> ...


I am curious as to how you approach bearing design in models where the crankshaft actually rides on a hydraulic oil film shifted a small amount off center in the engine being modeled. I would think the location and design of how the oil is given to the bearing would be critical even for models.  Or are the rpms and diameters involved in the model assumed to be metal to metal contact? Or are only the mains pressure lubricated and the connecting rods getting oil by a slinger thrower.  I dont know so thought I would ask.


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## peterl95124 (Dec 14, 2022)

all my split bearings have always been made from "bearing bronze", here in the U.S.A. that's CA 932 also known as SAE 660, about 7% tin, 4% zinc, 7% lead.  I tried to go cheap once early on and use brass but noticed that it tended to gall a lot so quickly switched to bearing bronze before trying to even start the engine.  brass on steel is a big no-no is what I found out later.  in general aluminum on steel is also a no-no, except 7075 seems to work, so I always make my con rods out of 7075 and run them directly on the crank pins without an additional bearing (A trick I learned from BAEMClub).  so if I were to use aluminum for a split bearing material it would have to be 7075 (5% zinc aircraft aluminum). Note that we always use crank shafts that are drilled for oil passages from the mains to the pins to keep those con rods lubricated with pressurized oil.


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## Zeb (Dec 14, 2022)

I always liked using oil-impregnated bronze (SAE841) for on-the-fly sleeve bearing projects.
Babbit would be interesting to try on a model engine. Might be overkill but oh so smooth.

Galling charts have stainless and brass way up there in the not so good.


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