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FarmerBill Samba Member
Joined: July 25, 2017 Posts: 762 Location: New England
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Posted: Mon Jun 21, 2021 6:50 pm Post subject: Re: Found the brass main thrust bearing |
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Talked to a friend of mine, and he tells me Lead/Bronze bearings (up to 20% lead) are still used in big diesel engines. They're supposedly more forgiving of dirty oil like you get on construction sites or farming. The high lead content allows for embedability and reduces scoring on the journals. I thought they phased them out by the 60s but he says they're still out there. Maybe your bearing is some sort of off-road prototype? |
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evanfrucht Samba Member
Joined: July 24, 2016 Posts: 2180 Location: Laurel Canyon, CA
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Posted: Mon Jun 21, 2021 7:05 pm Post subject: Re: Found the brass main thrust bearing |
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It seems homemade to me because of the crude tool marks on the inside oil groove.
I think who ever made it knew what they were doing tho and basically copied a type of bronze thrust bearing design used in another application that they were familiar with. I could also imagine someone in a rural setting, back before the internet, just making one vs going through the trouble of ordering a whole set of bearings... maybe they just needed the one during a bare bones "rebuild."
I feel like that theorey would sort if line up with what everyone else has suggested so far too. _________________ 1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder ) |
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oprn Samba Member
Joined: November 13, 2016 Posts: 12632 Location: Western Canada
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Posted: Tue Jun 22, 2021 4:41 am Post subject: Re: Found the brass main thrust bearing |
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Vanapplebomb wrote: |
My guess is crank wear could be accelerated from lack of embed-ability. If steel particles are present in the oil, they won’t embed into the bearing, away from the crank. they will stay in the hydrodynamic oil film between the crank and bearing, and grind the crank. |
That is the only down side I see too and is why the idea of tinning it with solder came to mind. Not that I will actually do it... but the original machinist could have improved it in that way.
I'm of the same opinion as evanfrucht on the origin of this bearing, just a one time, one off thing by a very competent old school machinist. _________________ We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age) |
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Vanapplebomb Samba Member
Joined: November 03, 2010 Posts: 5389 Location: Holland, MI
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Posted: Tue Jun 22, 2021 7:04 am Post subject: Re: Found the brass main thrust bearing |
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It’s not a bad idea to coat it. Most soft solders like lead/tin have a pretty low melting point. Higher melting point solders are typically harder, like silver solder.
With a torch, you could melt lead down and maybe pour that into the bearing and machine out what you don’t need. _________________ 1800 Type 4 Berrien 295
http://www.thesamba.com/vw/forum/viewtopic.php?t=487021 |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Tue Jun 22, 2021 7:47 am Post subject: Re: Found the brass main thrust bearing |
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oprn wrote: |
Vanapplebomb wrote: |
My guess is crank wear could be accelerated from lack of embed-ability. If steel particles are present in the oil, they won’t embed into the bearing, away from the crank. they will stay in the hydrodynamic oil film between the crank and bearing, and grind the crank. |
That is the only down side I see too and is why the idea of tinning it with solder came to mind. Not that I will actually do it... but the original machinist could have improved it in that way.
I'm of the same opinion as evanfrucht on the origin of this bearing, just a one time, one off thing by a very competent old school machinist. |
That is the main wear risk as you and Vanapplebomb are both noting.
In reality ....even if its an aluminum bronze.....its not harder than the steel by any means. Its tough and very high density......but cannot really wear the steel due to its "hardness"
But.....there will be steel in the oil from day one.....micro particles.....and you are right. The bronze will keep the larger of those from embedding down into a soft surface.
That is both a positive and a negative. The ability to "embed" gets certain particles out of the way. It also keeps certain particles right on the surtace where they just keep wearing and wearing.
One of the other issues.....I think someone else here was pointing this out. .....and it's why I am betting this is a bronze alloy. Brass....is actually fairly soft and malleable as far as compression loads go. Once you run it for a while as a bearing.....the compression loads deform it and it stays deformed.
Bronze has better.....elasticity.....for lack of a better word. Keeping in mind that babbits.....are an alloy of usually harder materials suspended in softer materials (a harder metal and a softer base metal).
The softer metal wears away a little from the smaller particles of harder metal.....leaving support peaks with valleys in between to carry lubricant film.
So something like an aluminum bronze bearing alloy can be thought of as a higher density babbit. Its made of softer and harder metals.
But.....getting back to the point I was,trying to make.....I "think" from where I have seen aluminum bronze bearing materials succesfully used......its hard enough in comparison to ferrous metals....that there can/will be galling of the bronze because of the speed combined with pressure and hardness.
Most of the aluminum bronze bearing alloys I have seen in use are in machines.....running against journals that are either hardened or sleeved ....and running far lower speeds than an engine bearing.
So......just wondering.....have you checked this odd bearing to see if its round....and it it corresponds to any normal crank size or oversize? It might shed some light on why it was used. Ray |
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Vanapplebomb Samba Member
Joined: November 03, 2010 Posts: 5389 Location: Holland, MI
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Posted: Tue Jun 22, 2021 9:05 am Post subject: Re: Found the brass main thrust bearing |
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raygreenwood wrote: |
So......just wondering.....have you checked this odd bearing to see if its round....and it it corresponds to any normal crank size or oversize? It might shed some light on why it was used. Ray |
This. I would be interested in the ID and OD. _________________ 1800 Type 4 Berrien 295
http://www.thesamba.com/vw/forum/viewtopic.php?t=487021 |
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oprn Samba Member
Joined: November 13, 2016 Posts: 12632 Location: Western Canada
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Posted: Tue Jun 22, 2021 11:22 am Post subject: Re: Found the brass main thrust bearing |
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See post #5. Just a cheap caliper but should be close enough to answer that question I think. _________________ We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age) |
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FarmerBill Samba Member
Joined: July 25, 2017 Posts: 762 Location: New England
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Posted: Tue Jun 22, 2021 11:41 am Post subject: Re: Found the brass main thrust bearing |
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Lead/bronze bearings were used along with poured babbitt bearings and God knows how many other alloys of whatever else in gas engines in the early days. I found an article from1940 about leaded bronze bearings being fine ,as long as the journals were sufficiently hardened.
https://www.jstor.org/stable/44429095
Of course this was back when most engines redlined at around 3500 rpms or less. Hell, International was making engines back then that maxed out at 1600 rpms. Like Ray pointed out, the faster the journal spins in the bearing the more likely it is to gall. Probably the reason that as engine rpms increased lead/bronze bearings disappeared. But, like I said according to my friend, Lead/Bronze bearings are still being used in big diesels. |
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oprn Samba Member
Joined: November 13, 2016 Posts: 12632 Location: Western Canada
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Posted: Tue Jun 22, 2021 12:18 pm Post subject: Re: Found the brass main thrust bearing |
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Can't detect any out of round with these calipers, maybe if I cracked out the micrometers, so if it's egged it's not my much. _________________ We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)
Last edited by oprn on Wed Jun 23, 2021 4:35 am; edited 1 time in total |
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calvinater Samba Member
Joined: September 06, 2014 Posts: 3306 Location: 802
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Posted: Wed Jun 23, 2021 2:22 am Post subject: Re: Found the brass main thrust bearing |
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calvinater wrote: |
Wouldn't that just pound the case harder than a standard bearing? |
I was referring to the thrust wear on the case since bronze/brass is harder than aluminum. _________________ "Albatross"! |
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oprn Samba Member
Joined: November 13, 2016 Posts: 12632 Location: Western Canada
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Posted: Wed Jun 23, 2021 4:39 am Post subject: Re: Found the brass main thrust bearing |
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Not sure. It seems the stock aluminum bearings might be harder than the case too as the case is the part that always seems to end up taking the bulk of the beating. _________________ We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age) |
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