Author Topic: Loop main bearing material  (Read 831 times)

Offline Garmst

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Loop main bearing material
« on: March 28, 2019, 01:02:32 AM »
Anyone know what material is used for main bearings in early models?

Offline Don G

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Re: Loop main bearing material
« Reply #1 on: March 28, 2019, 11:08:52 AM »
As far as I know the main bearings are some form of Aluminium alloy, the rod bearings are claimed to be Al-Tin , look up King Bearings catalouge , it explains different bearing alloys etc.  DonG


Online Tony F

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Re: Loop main bearing material
« Reply #2 on: March 28, 2019, 03:29:44 PM »
I've had bearings made before using a material called free machining aluminum. I've also seen it referred to as alloy 2011. I was told it has some lead included in the formulation which makes it easier to machine but on doing a bit of research it seems to have far more copper than lead in it.

Presumably something along these lines was used originally??

Online Kiwi_Roy

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Re: Loop main bearing material
« Reply #3 on: March 28, 2019, 03:54:08 PM »
Don't know but they must have got it right, look at all the models this fits
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http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_126&products_id=36
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http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_126&products_id=188
« Last Edit: March 28, 2019, 04:00:39 PM by Kiwi_Roy »
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Offline canuck750

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Re: Loop main bearing material
« Reply #4 on: March 28, 2019, 08:06:49 PM »
I don't know what its made of but it cuts easier than the engine block alloy. :evil:
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Online Muzz

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Re: Loop main bearing material
« Reply #5 on: March 28, 2019, 09:44:56 PM »
Around that era, would it be copper/lead?
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Offline Garmst

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Re: Loop main bearing material
« Reply #6 on: March 29, 2019, 01:01:20 AM »
Thanks for all the replies. There are so many alloys it's hard to know where to begin. Tony F, do you mean you have had main bearings made before? If so, how have they worn?
I have machined old bearings to fit a crank but it's so long ago I can't remember how it behaved. I guess I could look at the specs of bimetal bearings and see how these compare to billet alloys.

Online Rough Edge racing

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Re: Loop main bearing material
« Reply #7 on: March 29, 2019, 06:07:38 AM »
Around that era, would it be copper/lead?

  Probably, lead/copper on a steel backing, AKA Clevite 77 type and still in use for performance and heavy duty use...I believe the bi metal bearing is  more recent and is popular in newer vehicles and for performance...Beari ng inserts are a precision product and the material layers are very thin..
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Online Antietam Classic Cycle

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Re: Loop main bearing material
« Reply #8 on: March 29, 2019, 08:58:31 AM »
My question is why bother? I mean, it's not like main bearings aren't available and they're less costly now than they have been in quite some time.
Charlie
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Online Muzz

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Re: Loop main bearing material
« Reply #9 on: March 29, 2019, 03:21:24 PM »
  Probably, lead/copper on a steel backing, AKA Clevite 77 type and still in use for performance and heavy duty use...I believe the bi metal bearing is  more recent and is popular in newer vehicles and for performance...Beari ng inserts are a precision product and the material layers are very thin..

Sounds like the stuff.  I am pretty sure those were the high zoot bearings that went in to racing Minis in the late 60's.
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Online Tony F

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Re: Loop main bearing material
« Reply #10 on: March 29, 2019, 04:02:10 PM »
Tony F, do you mean you have had main bearings made before? If so, how have they worn?

They've worn well, or not worn to be more precise! I've had several sets made. If the clearance is correct and the oil pressure is good in theory there should be very little, if any, wear.

At the time I first had it done (close 30 years ago) it was a significant cost saving over new bearings. Plus it was a challenge! The price has come down as Antietam points out so the economics would be different now.

The big end bearing shells were changed to a softer material when the Le Mans 3 was introduced which is the reason for the superceeded part number shown in the MGCycle listing.

Tony

Offline Garmst

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Re: Loop main bearing material
« Reply #11 on: March 29, 2019, 07:12:35 PM »
Morning. There appears to be confusion in the thread. I am not asking about big end bearings (bimetallic) I am asking about main bearings which I consider to be very expensive but simple to make if I had the correct material.
i.e.
https://www.harpermoto.com/rear-main-bearing-u-s-2mm-12011401.html

Online Antietam Classic Cycle

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Re: Loop main bearing material
« Reply #12 on: March 29, 2019, 08:06:43 PM »
Morning. There appears to be confusion in the thread. I am not asking about big end bearings (bimetallic) I am asking about main bearings which I consider to be very expensive but simple to make if I had the correct material.
i.e.
https://www.harpermoto.com/rear-main-bearing-u-s-2mm-12011401.html

Shop around...
http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_126&products_id=189
Charlie
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Online Tony F

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Re: Loop main bearing material
« Reply #13 on: March 30, 2019, 02:29:15 AM »
Morning. There appears to be confusion in the thread. I am not asking about big end bearings (bimetallic) I am asking about main bearings which I consider to be very expensive but simple to make if I had the correct material.
i.e.
https://www.harpermoto.com/rear-main-bearing-u-s-2mm-12011401.html

I hope the comments on the material have been helpful. I don't think it took very long, are you able to do the machining yourself?  If so that makes the exercise very cheap. Good luck, let us know how you get on.

Online Rough Edge racing

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Re: Loop main bearing material
« Reply #14 on: March 30, 2019, 06:39:27 AM »
Morning. There appears to be confusion in the thread. I am not asking about big end bearings (bimetallic) I am asking about main bearings which I consider to be very expensive but simple to make if I had the correct material.


  And what is the correct material?
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Offline Garmst

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Re: Loop main bearing material
« Reply #15 on: March 30, 2019, 08:12:49 PM »
 'And what is the correct material?' If Tony F is referring to main bearings, and not big ends, he thinks free machining Al was used to make his. Possibly this is all that's required but given the range of materials available I will do some more research.

As an aside I used to make valve guides and seats from Al bronze which is an amazing wear resistant material and machines nicely (just don't try to drill a hole in it with a HSS bit). I guess this is why it is such a good material for these purposes. But it might be too hard for a bearing and wear out the crank when oil pressure is low, perhaps at start up. I'll have to get a test bike and try it (he dreams).

Online Rough Edge racing

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Re: Loop main bearing material
« Reply #16 on: March 31, 2019, 06:14:42 AM »
 Main bearing or rod bearing, makes no difference. Are there any high output engines, And Guzzi is high output, using solid aluminum for main bearings? There are many engines with the cams runs directly on aluminum...but the engine crank are bearings subject to reciprocating loads at 7000 plus RPM And as you mentioned, without the ability for debris to embed in the soft bearing material, crankshaft journals may not last too long..
  I'm also thinking the two Guzzi main bearings need to be line honed in place unless they are factory made stuff .
  About 15 years ago , vintage Triumph rod bearings, common split variety, were getting hard to find. Several known long time Triumph tuners along with Baxter Cycle talked to Mahle who took over Clevite bearing production in the USA..They were able to order a certain number and so now high quality bearings for old Triumphs are available for reasonable money..Maybe this won't work for the Guzzi situation...
« Last Edit: March 31, 2019, 06:15:35 AM by Rough Edge racing »
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Online pete roper

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Re: Loop main bearing material
« Reply #17 on: March 31, 2019, 02:54:48 PM »
Main bearing or rod bearing, makes no difference. Are there any high output engines, And Guzzi is high output, using solid aluminum for main bearings? There are many engines with the cams runs directly on aluminum...but the engine crank are bearings subject to reciprocating loads at 7000 plus RPM And as you mentioned, without the ability for debris to embed in the soft bearing material, crankshaft journals may not last too long..
  I'm also thinking the two Guzzi main bearings need to be line honed in place unless they are factory made stuff .
  About 15 years ago , vintage Triumph rod bearings, common split variety, were getting hard to find. Several known long time Triumph tuners along with Baxter Cycle talked to Mahle who took over Clevite bearing production in the USA..They were able to order a certain number and so now high quality bearings for old Triumphs are available for reasonable money..Maybe this won't work for the Guzzi situation...

Well it does, because Guzzi big blocks don't use shell type main bearings. The front and rear bearings are a two part bearing with a cast outer flange with a pressed in 'Tunnel' type bearing. My guess would be that the most important thing would be to use an alloy with a similar C of E to the flange alloy for the bearing tube as too great a difference will cause either the bearing tube to deform or to become loose as the engine heats up.

In fact loosening can and will be a problem if you forget to install the oil feed dowels in the bearings before they are assembled into the case. Not installing the front can be very amusing, at least temporarily, as when the bearing spins and the oil feed galleries in the bearing and flange no longer line up the front cam bearing and oil pressure light switch no longer get pressure. This results in an oil light that will flash as the bearing rotates within the flange which is very vexing. Not as vexing as the seizure that occurs shortly thereafter but vexing none the less! :evil:

In the past, when helping impoverished mates get going again after they've had a catastrophe, I have pushed a healthy bearing tunnel out of a buggered flange, (This is usually the result of people trying to remove the flange without the proper puller and breaking off one or more of the bosses that the bolts go through.) and then re-installed it in another, un-munted, flange. Obviously it's important to remove the oil feed/locator dowel first and take care pressing the bearing into the flange so the holes line up and while far from ideal it has worked to get them back on the road in extremis.

As stated, what the bearing is made out of isn't really that important as long as it's soft. You can run anything on anything pretty much as long as the clearance is correct. The problems will occur if the material of the bearing can't allow particulate matter to embed. In that case it will force boundary lubrication and the whole thing will go 'Udders Skywards' in very short order.

Pete

Offline Chuck in Indiana

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Re: Loop main bearing material
« Reply #18 on: March 31, 2019, 06:17:19 PM »
When looking at this problem back in the day, and seeing how much those things cost, (!) I was going to machine new bearings out of aluminum, and press them in. Life got in the way, and it didn't happen..but.. I'll bet that would have worked. <shrug>
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Online Rough Edge racing

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Re: Loop main bearing material
« Reply #19 on: March 31, 2019, 07:23:57 PM »
Well it does, because Guzzi big blocks don't use shell type main bearings. The front and rear bearings are a two part bearing with a cast outer flange with a pressed in 'Tunnel' type bearing. My guess would be that the most important thing would be to use an alloy with a similar C of E to the flange alloy for the bearing tube as too great a difference will cause either the bearing tube to deform or to become loose as the engine heats up.

Pete

 Pete,  what is the material of the pressed in tunnel bearing...? Is a multi layer construction, as in not a piece of aluminum? Pehaps like the right side sleeve bearing used on BSA and a few other Brit bikes?
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Offline Garmst

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Re: Loop main bearing material
« Reply #20 on: March 31, 2019, 07:27:33 PM »
I have asked the question at eng.tips.com and will see if this bears fruit. I agree that the coef of exp. must be a consideration but given there are pins securing it's not the only one. Perhaps I'm over thinking it and it is just a lump of free matching Al.
I see cyclegarden make their own. I wonder if they'll tell us what they use.

Online pete roper

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Re: Loop main bearing material
« Reply #21 on: March 31, 2019, 07:51:20 PM »
Pete,  what is the material of the pressed in tunnel bearing...? Is a multi layer construction, as in not a piece of aluminum? Pehaps like the right side sleeve bearing used on BSA and a few other Brit bikes?

Just an aluminium sleeve as far as I can make out at the rear. The front one is stepped with the thrust face machined into the bottom of the 'Brim' of the top-hat construction. I'd post some pics but I sold all of my pre-2,000 stuff a few weeks ago.

Offline AJ Huff

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Re: Loop main bearing material
« Reply #22 on: March 31, 2019, 10:09:46 PM »
Look up 850 Aluminum.

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Online Rough Edge racing

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Re: Loop main bearing material
« Reply #23 on: April 01, 2019, 07:49:52 AM »
 This is what I know about aluminum bearings...They are a a special grade of aluminum that is bonded to a steel shell...This is the type of bearing you'll find in most new cars and maybe some bikes..The bearings are split for ease of assembly but could be one piece..

         http://kingbearings.com/files/Engine_Bearing_Materials.pdf

   



         
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Offline Garmst

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Re: Loop main bearing material
« Reply #24 on: April 01, 2019, 06:08:01 PM »
Moe from Cycle Garden uses 936 Bronze. Previously used 6061 alloy but had a problem with it.

http://www.advancebronze.com/alloy-charts.php
936 bronze
'The high leaded tin bronzes contain the most widely used bearing bronze alloy C932 (also known as SAE 660). Widely available and somewhat less expensive than other bearings alloys - it is known for its unsurpassed wear performance against steel journals. It can be used against unhardened and not perfectly smooth shafts. Lead weakens these alloys but imparts the ability to tolerate interrupted lubrication. It also combines favourable antifriction properties with good load-carrying capacities and will conform to slight shaft misalignments.'

sounds good.

Online pete roper

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Re: Loop main bearing material
« Reply #25 on: April 01, 2019, 06:47:37 PM »
Id confirm that he C of E is compatible.

 

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