sintered bronze main bearings vs alum steel

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AC sports
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sintered bronze main bearings vs alum steel

Post by AC sports »

I recently rebuilt an engine for a customer that supplied me with bearings etc.
I checked clearances and all was fine but later went to order another set for a similar build and they are not listed for that particular car but for a similar diesel model.
The difference is one bearing is steel backed sintered bronze, the other steel backed aluminium that's lead free.
What are the pro's and cons of each. Would they interchange ?
What's best for high rpm ?
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Re: sintered bronze main bearings vs alum steel

Post by jed »

I have never heard of a steel backed sintered bronze main bearing. What was the application and the manufacture
Of the bearing??
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Re: sintered bronze main bearings vs alum steel

Post by Truckedup »

In the early 1920's , Allison Engineering ( they later made the V12 aircraft engine) developed a process to put a bronze overlay on a steel shell. This was first the "modern bearing" just like used now with different metals on a steel shell...
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Re: sintered bronze main bearings vs alum steel

Post by Dave Koehler »

Are you sure it was actually bronze and not just that copper/bronze look that some bearings have?
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Re: sintered bronze main bearings vs alum steel

Post by CharlieB53 »

I may have it all wrong, but it would seem to me that a bronze surfaced bearing could handle much greater pressures created in a diesel motor than a softer bearing.

Although the softer bearing layer does have the advantage of more easily 'embedding' and trapping any small hard particle that may be carried in the oil.

Many diesels do have much better oil filtering than our cheap automotive filters. Old Macks had a centrifugal filter that I would have liked to have seen used more. They were a bitch to clean, but they did their job.
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Re: sintered bronze main bearings vs alum steel

Post by AC sports »

Well the interesting thing is they also looked like they have an aluminum top layer cause I couldn't tell the difference in appearance ,yet the Glyco bearing catalog lists them as sintered bronze over steel.
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Re: sintered bronze main bearings vs alum steel

Post by modok »

Glyco is very rare in the USA, so I do not think I have ever seen one.
Then again, in appearance, it may be identical to a cast bronze (or copper/lead) steel backed bearing.....so....how would I know if I ever did? LOL

Sintered metal is 10-20% porous, as a result...in MOST cases, it cannot be as strong and fatigue resistant as a solid cast material. So I would SUSPECT it would be unlikely to be used in a connecting rod, and probably not a main bearing either.

It is easy to machine, so may be very good for camshaft bearings that are machined after installation, and balance shaft bearings, gear train bearings.

If glyco has made some kind of proprietery process that makes a sintered bearing AS STRONG as a cast bronze bearing, I haven't heard of it. I would be suspicious of it's low popularity.

Steel shell aluminum bearings are used in 70% of all engines that currently exist, so, there should be no need to explain.
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Re: sintered bronze main bearings vs alum steel

Post by PackardV8 »

Only slightly OT, but the American LaFrance V12 we are building was designed by Auburn/Lycoming in the late '20s-early '30s and at that time had poured babbit main bearings. When ALF redesigned it for insert mains, they left the main journals the same large diameter and had the main bearings made up with 1/4" thick bronze shells with babbit overlay. I'll post a photo.
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Re: sintered bronze main bearings vs alum steel

Post by Truckedup »

PackardV8 wrote: Mon Mar 19, 2018 11:29 am Only slightly OT, but the American LaFrance V12 we are building was designed by Auburn/Lycoming in the late '20s-early '30s and at that time had poured babbit main bearings. When ALF redesigned it for insert mains, they left the main journals the same large diameter and had the main bearings made up with 1/4" thick bronze shells with babbit overlay. I'll post a photo.
Jack, that's interesting about bronze shells with babbit....The Allison Engineering story I mentioned above came from Allison being hired by the Army Air Force to extend the overhaul life of the WW1 Liberty V12 aircraft engine still in use. The rod and main bearings were only good for about 50 hours...They were babbit over bronze as was common back then...Allison's bronze over steel increased TBO to around 400 hours even when power was increased about 25%...The bronze over steel then evolved into the tri metal...
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Post by dwilliams »

exhaustgases wrote: Sun Mar 18, 2018 7:12 pmSome old cat engines used Al bearings.
I made some main and rod bearings for an antique tractor out of aluminum bar stock. The originals were some kind of thickwall shells; I had to mike the block and crank and SWAG the dimensions since the old bearings had been thrown away.
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