Sealed Power MA series bearings

[Machspeed]

I came across these while ordering some parts for a build. I'm not sure I completely understand why someone would use these. Why would you want a bearing that polishes your crank?

https://www.summitracing.com/parts/slp-4125ma?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-sealed-power&gclid=EAIaIQobChMInPPI-Of83wIVCo_ICh3gXgRXEAQYCCABEgKT8PD_BwE


Description: These Sealed Power MA Series main bearings can actually polish the journals on your crankshaft. That's because there's a small percentage of silicon mixed in with the aluminum and tin that make up the bearing-surface alloy. The silicon is there for wear resistance, but its toughness actually smoothes the journals of a crank whose surface hasn't been optimized! This special surface alloy is laid over a high-strength 1010 steel backing and delivers improved seizure and corrosion resistance, as well as better control of wall variance. It also helps to minimize debris embedding, which can score the crank's surface.

[67428GT500]

The price says much about them. Half the price of the Clevite 77 most of us use. I always micropolish. No need for an abrasive.

                                                                                          -Keith

[Machspeed]

I don't agree with the "if it costs more it must be better" approach but I get the point of using quality parts. I've used Clevitte, King and a few others before with no problems. I just noticed the suffix on this part number when looking at what the local Summit had in stock. I wasn't necessarily looking at purchasing these but the MA sparked my curiosity. I've never seen a bearing with an abrasive or advertised like this.

[Heo]

There was something similar in the 50s, called red bronze
bearings. For when you had a crank with scratches. like a
band aid repair to get some more mile out of an engine,
without machine work my dad told me.
 I had a set in a flathead i disassembled
Dad told me those bearings lasted, but it wore down the crank

[Machspeed]

That's something I am curious about. When does the polishing stop?

[fekbmax]

I understand these type bearings are ment for show cars and restorations ect, cars that sit alot and do not get ran or driven often. Back yard re bearing jobs where it's a quick clean up and re bearing job. You know, the garage squad...  lol

[Barry_R]

Good grief.  A lot of assumptions, some poorly conceived marketing hype, and we have bad information. The MA bearings are simply the same material used in darn near every new car - - the ones that will go hundreds of thousands of miles with minimal wear.  It's an aluminum alloy on a steel backing.  The alloy has a bit of silicon in the mix, somewhat similar to a hypereutectic piston.  The silicon adds hardness and wear resistance to the otherwise soft aluminum.  They ( the manufacturing facilities both aftermarket and OEM) like aluminum bearings because it helps remove lead from the products and the plants, and satisfies EPA regulators.

The upsides to aluminum as a bearing material have always been low cost, resistance to snagging/sticking to the crank, and environmentals.  The downsides have been fatigue resistance and wear.  The silicon and alloy development have addressed those weaknesses and made it into a good bearing choice.  The hard material will not embed debris like an old soft bearing - hence some marketing wordsmith thought it would be an advantage to state that they would polish a crank in service - making the hardness an advantage instead of a disadvantage.  When I left F-M a decade or so ago, aluminum was considered satisfactory for clean environments (passenger cars and light trucks) with power levels up to perhaps a hundred horsepower per liter.  I am certain that given the time and advances in technology, that those levels have gone way up.

I still prefer a multilayer bearing (Clevite has a trademark on the term "Tri-metal") for my builds - and want a 1/2 groove or 3/4 groove design, but a street guy won't be in trouble with an aluminum bearing from an alloy perspective.

[fekbmax]

Well there you have it, great information from someone that actually would know. Thanks for clearing that up.
No doubt you can't always go off what you been told from your local classic restorations shop.

[Machspeed]

Thanks Barry. I was hoping you would chime in considering you have more experience with bearings than most anyone. I picked up my order this morning and asked if I could see a set of the MA bearings. They look like any other aluminum bearing I've ever seen. The surface is smooth and nothing like what the description may lead you to think. I just thought it was a really weird way to market a bearing.   

[cjshaker]

I thought the whole idea behind lead was so that the bearing WOULD let debris embed in it, instead of gouging the snot out of the crank journal? So now it's a good idea to NOT embed debris? That sounds like they're trying to take something that's inferior, and make it sound like a good thing, which is typical of marketing these days. I'd go a step further than calling it "hype" and just call it what it is...bullshit.

[Barry_R]

I thought the whole idea behind lead was so that the bearing WOULD let debris embed in it, instead of gouging the snot out of the crank journal? So now it's a good idea to NOT embed debris? That sounds like they're trying to take something that's inferior, and make it sound like a good thing, which is typical of marketing these days. I'd go a step further than calling it "hype" and just call it what it is...bullshit.

That "used to be" the idea - for a bearing to embed debris.  Goes way back to flat heads and oil dippers.  If you are changing oil and using any kind of decent filter there should not be any significant debris in the oil - and certainly not anything large enough to be embedded into a bearing.  Race bearings have nearly no embedability, nor do the bearings in most of the newer engines that go literally hundreds of thousands of miles between service intervals. 
"Dem dayz is gone" for that particular characteristic.


Now lead remains a darn good material for bearing alloys because its conformable, and has good lubricity.  Just don't spread it on your sandwich.

[Joe-JDC]

It has been my experience that when things embed in a bearing, it scratches the journal.  I would much prefer the "trash" to be caught by the filter and not stick into a soft bearing and keep grinding a groove in that journal.  Joe-JDC

[cjshaker]

It has been my experience that when things embed in a bearing, it scratches the journal.  I would much prefer the "trash" to be caught by the filter and not stick into a soft bearing and keep grinding a groove in that journal.  Joe-JDC

But the reality is, IF a piece of material gets in the oil system, if it doesn't embed in the bearing, it's going to gouge the journal MUCH worse than if it embedded in the bearing. That's the whole idea of it embedding. And despite having filters, debris still can find its way into the system. That's the reason I went with a filter that has no bypass.

I get that everyone doesn't want anything in the oil system that will cause damage, yet it still happens. We don't live in a perfect world, and we don't have engines that are designed and built like modern engines. But even then, nobody rebuilds these newer engines in standard production cars, they throw them away and get another one. I can't see these bearings being a good alternative to standard lead backed bearings in anything less than a race engine that needs hard backed bearings. Just my opinion.

[RustyCrankshaft]

I've rebuilt a number of high mileage mod motors, usually 5.4's and V10's out of trucks, and I've seen a few that have obviously had crap go thru them. I've seen it happen by the oil samples as well. A lot of these are fleet vehicles so I can go back and look at oil samples that were done fairly consistently. When I tear one down and find a scratch (well, with Al bearings it's more of a groove LoL) I can go back and look at the oil samples and actually see the "particle streak" where you get a huge jump in aluminum/iron for one oil change and then back to normal. What always amazes me, is that it's rare have I seen a crank journal damaged bad enough that a simple polish didn't fix it in these cases. Yet the bearing looks like a boulder went thru it. Usually when I do it's because the engine had an oil system related failure rather than just being worn out (as in the moron company driver went 15k miles without checking the oil, etc.). Obviously the particular alloys have changed, and machining tolerance is better, etc. but I generally see less crank wear in a modern engine vs older stuff with traditional multilayer/soft overlay bearings. 99.5% of all this is on stock/fleet or big diesels, the hotrod stuff I don't get to do nearly as much as I'd like and on true street/strip and race engines results might differ.

I'm sure there are exceptions, but the modern "hard" bearings do seem to work well in a lot of applications. I also agree that marketing a bearing based on it's ability to polish the crank due to "Abrasives" in the bearing seems odd and counterproductive.