BE Bearings In-Depth: Oil Flow, Oil Pressure Analysis

[undecided]

Originally Posted by pbonsalb

The S85 came out in the 2005 E60 M5. It was just 3 years later the S65 came out in the 2008 E90 M3. Maybe from the S85 failures at that point in time, no conclusions were made.

It took a while before bearings were identified as a problem even on the S85. An acquaintance who is working at BMW has mentioned that they are now noticing the bearings as a problem only because of the increasing amount of failures. Unfortunately for us, the cars with the problem are way out of warranty even for their good will program.

[Green-Eggs]

Originally Posted by Sneaky Pete

My preferred choice would be a bearing with extra clearance made up with a coating to the OEM clearance.
if I was in the market and BE bearings sold that product then they would be my preferred supplier rather than VAC.
BE bearings seem more professional, have a good presence here and are very well respected.
The one single reason to go with VAC is that only they sell this product.

BE does sell exactly that product as well. BE was always willing to sell that product to anybody who specifically asked for it. This has been mentioned in the past, and may be mentioned in the group buy thread. Since BE Bearings are all individually measured and sized binned, anybody who wants OEM clearance can ask for it, and they will receive a set of the "thick binned" bearings. That was in the past; now it's even easier for BE. BE now offers +0.001 bearings as well. +001 shells are thicker by 0.0005 for each shell (so both shells equal +001). If you want a full set of OEM clearance bearings, be sure to order the +0.001 version. A set of +001 bearings will measure within a tenth or two of OEM clearance. Then for anybody who wants to get more precise, BE has also always been willing to exchange shells of various thicknesses to make up a custom set of any clearance a customer wants. The way that works is for the customer to order and measure the clearances on the bearings they receive. Then contact BE Bearings and request shells individually to make up the target clearance. This is exactly how race shops individually size bearing shells to obtain a target clearance.

So getting OEM clearance has always been possible with BE and this has been mentioned before. However, with the addition of +001 bearing shells, it's even easier now than before. But the option has always been there.

[Bartledoo]

Has there been any measurement of clearance at different assembly temperatures (0, 100, 200, 250F, etc). I'm curious how the varying thermal expansion of the different rod, crank, and bearing materials may affect the clearances and/or shape, particularly given the greater clearance of the aluminum/tin bearings without noticeable improvement in probability of failure. I do realize the shape was changed with the aluminum/tin bearings as well though. I'm also curious because of the high failure rate in hot climates.

[undecided]

Originally Posted by ksteckba

Has there been any measurement of clearance at different assembly temperatures (0, 100, 200, 250F, etc). I'm curious how the varying thermal expansion of the different rod, crank, and bearing materials may affect the clearances and/or shape, particularly given the greater clearance of the aluminum/tin bearings without noticeable improvement in probability of failure. I do realize the shape was changed with the aluminum/tin bearings as well though. I'm also curious because of the high failure rate in hot climates.

Like if there is a geographic relationship to the failures? I know auto manufacturing is done in climate controled facilities so I do not think that would be an issue.

[Obioban]

Originally Posted by Sneaky Pete

This thread more than demonstrates the basic problem with the BE Bearing "fix".
They don't know the oil flow rate over the bearings.
They don't know the distribution of oil pressure over the bearing surface.
They don't know the temperature gradient of the oil as it flows through the bearing.
They don't know the bearing loads.
They don't know the oil film peak pressure.
They don't have flow charts for the oiling system.
etc etc.
In fact they have pretty much none of the important data that BMW can use to software model the bearing environment and calculate the optimum clearance and of course predict how that environment would change at different clearances.

Anyway, bless you all for having faith that BE bearings are smarter than BMW when they so clearly are blundering around in the dark.
Peace and good luck.

It is not reasonable to expect a small manufacturer to be able to collect this level of data. Hell, the information presented in this thread is far and above the norm. The tools required for the data you're asking for would make any bearing project a non started.

At this point, there's no question BMW's engineers got it wrong, even with all that data. Far from the first time they've gotten something wrong, too-- they're far from faultless.

Do I think these are a fix? I don't know. But, I do know the stock design is flawed. So the assumption that BMW got it right, because they had access to that data, is as flawed as the bearing design is.

[Obioban]

Originally Posted by undecided

Like if there is a geographic relationship to the failures? I know auto manufacturing is done in climate controled facilities so I do not think that would be an issue.

Nope, no correlation with location or climates exists.

[Bartledoo]

Originally Posted by undecided

Like if there is a geographic relationship to the failures? I know auto manufacturing is done in climate controled facilities so I do not think that would be an issue.

No not really. My interest is how the clearance (and its variation circumferentially) changes throughout the range of operating temperatures seen by this engine (and for each different bearing type). One of the reasons for my curiosity is that the forum is always speaking about excessive wear during very cold temperatures, yet we see many failures in hot climates.

[Sneaky Pete]

Originally Posted by Green-Eggs

So getting OEM clearance has always been possible with BE.

What thickness coating does that include..something similar to VAC?
Its certainly a good option that clearly is not as well publicised as it could be.

[BMRLVR]

Originally Posted by Sneaky Pete

What thickness coating does that include..something similar to VAC?
Its certainly a good option that clearly is not as well publicised as it could be.

The binning has been mentioned already and a call or email to BE would have gotten you the info you wanted in a hurry. If you spent a little less effort on trying to write of these bearings and asked a few more questions you'd realize that a lot of time and effort went into getting these to market.

To make sure the bearings were right before coming to market, many Automotive and Motorsports professionals were consulted..... Then after the bearings got to market, and the first batch were mostly sold out, BE still stuck with the testing program so that the info could be shared with the community.

This testing program is not needed by BE since the bearings were selling like hot cakes without it, it was done because everyone involved with this is just as interested in providing the info for the good of the community and keeping our beloved S65's/S85's running, as they are with selling bearings. Many people are donating their time, knowledge, engines, cars, etc., so that this program is successful, all to help the community. If it weren't for the donated time, knowledge, engines and cars this program wouldn't have gotten off of the ground to begin with.

[Green-Eggs]

Originally Posted by Sneaky Pete

What thickness coating does that include..something similar to VAC?
Its certainly a good option that clearly is not as well publicised as it could be.

The Calico PTFE and the Clevite TriArmor coatings are both comparable thickness. Both are 0.0003 nominal thickness.

We believe BE's measuring and binning each shell is one their big advantages, especially for race shops who like to dial everything in precisely. When the +0.001 shells came along, I thought we mentioned the possibility that it opened the door to any reasonable clearance, including standard OEM clearance. Sometimes information like that does get lost, or isn't as clear as it could be...or maybe we forgot to mention it clearly like you said.

Hopefully everybody now knows they can order bearings in custom sizes. If they want factory clearance, then they should order a full set of +0.001 bearing shells. If they want something in between, they can order half and half. If they want full custom, they should measure their shells then contact BE for replacement shells of specified thickness.

[Sneaky Pete]

Originally Posted by BMRLVR

If you spent a little less effort on trying to write of these bearings

I stand by every single thing I said in post number 94.
The fact that you offer, as a result of "binning" extra clearance shells, bearings that actually match OEM clearance points to a worrying lack of tolerance control at Clevite and maybe explains why BMW dumped them as a supplier for the E9x M3 platform in the middle of the production run.

Wouldn't be the first time BMW has had significant problems with a supplier being unable to maintain tolerance or quality control standards.

Originally Posted by BMRLVR

you'd realize that a lot of time and effort went into getting these to market.

I don't doubt it...doesn't make the "tight clearance" concept any less flawed though.

[Sneaky Pete]

Originally Posted by Green-Eggs

The Calico PTFE and the Clevite TriArmor coatings are both comparable thickness. Both are 0.0003 nominal thickness.

We believe BE's measuring and binning each shell is one their big advantages, especially for race shops who like to dial everything in precisely. When the +0.001 shells came along, I thought we mentioned the possibility that it opened the door to any reasonable clearance, including standard OEM clearance. Sometimes information like that does get lost, or isn't as clear as it could be...or maybe we forgot to mention it clearly like you said.

Can't ask for better than that.
Having the possibility to match bearing shells to each journal to ensure all bearings have an equal clearance (albeit measured by plastigauge) is indeed a big advantage.

[pbonsalb]

Originally Posted by Sneaky Pete

lack of tolerance control at Clevite and maybe explains why BMW dumped them as a supplier for the E9x M3 platform in the middle of the production run.
.

How do you know BMW factory bearings from 2008-2010 had inconsistent tolerance?

How do you know BMW "dumped" Clevite? Maybe BMW put the new aluminum bearing contract out to bid and another maker had a lower bud.

[Sneaky Pete]

Originally Posted by pbonsalb

How do you know BMW factory bearings from 2008-2010 had inconsistent tolerance?

A degree of speculation; on the basis that Clevite (the 2008-2010 OEM supplier) currently manufacture "undersized" bearings for BE with sufficient tolerance drift that they can sort out sets that provide OEM clearance.
And on the inconsistency of RB wear seen on 2008-2010 cars.

Originally Posted by pbonsalb

How do you know BMW "dumped" Clevite? Maybe BMW put the new aluminum bearing contract out to bid and another maker had a lower bud.

I did say "maybe".
I know if I was in the market for a critical engine part I would be more concerned about long term reliability through accurate quality control than saving a few $$ in the short term.

[pbonsalb]

I thought you were against "maybe" or "speculation" in your rod bearing analyses?

[Green-Eggs]

Originally Posted by Sneaky Pete

A degree of speculation; on the basis that Clevite (the 2008-2010 OEM supplier) currently manufacture "undersized" bearings for BE with sufficient tolerance drift that they can sort out sets that provide OEM clearance.
And on the inconsistency of RB wear seen on 2008-2010 cars.

The blueprint for BE allows for 0.0004 variation in thickness. Out of all of the many thousands of shells received thus far, I think only five or fewer shells did not meet this tolerance. Those were the ones used for sanding down and exposing the layers of coating, lead, copper, and steel. The other four were tossed.

If you look at the empirical specs for BMW 088/089 Clevite bearings, and 702/703 Glyco bearings, they show 0.0003 variation in thickness. That's out of a sample size of only 16 shells. So I'm sure if you measured as many thousands of shells as BE has measured, you'd find they all, both Clevite and King, meet the same 0.0004 inch tolerance specification.
http://wiki.rcollins.org/core/index....5_Rod_Bearings

This observation leads to a very solid hypothesis that the only difference between the BMW BLUE (top) shells and BMW RED (bottom) shells is which end of the tolerance spectrum they fall. If you notice all of the BLUE (top) shells are about 0.00015 thicker than the RED (bottom) shells. Very likely, BMW is binning the shells exactly like BE and labelling the thicker tolerance shells top/blue, and the thinner tolerance shells bottom/red. If you take them all together, they have measured a 0.0003 inch spread -- exactly in line with the Clevite blueprints.

[BMRLVR]

Originally Posted by Sneaky Pete

The fact that you offer, as a result of "binning" extra clearance shells, bearings that actually match OEM clearance points to a worrying lack of tolerance control at Clevite and maybe explains why BMW dumped them as a supplier for the E9x M3 platform in the middle of the production run.

What you are describing is mass production and the inherent variance that is inevitable......To say Clevite is careless in maintaining tolerance control is laughable they are the largest manufacturer of bearing shells in the world and supply components to OEM, Aftermarket, Performance, and Racing industries...... This production variance exists in every mass produced component and solidifies the need for quality control and binning as BE is doing on 100% of the bearing shells they sell.

Different sized bearing shells to set clearances on the rotating assembly of any engine are extremely important and BMW is one of the few manufacturers that don't offer this. BE saw the lack of + 0.001 sized bearing shells and addressed it in the second production run of the bearings.

[Bartledoo]

...I'll take that as a "no". This thread got f'd. Can't get past the petty bulls*** with this crew.

[Green-Eggs]

Originally Posted by ksteckba

...I'll take that as a "no". This thread got f'd. Can't get past the petty bulls*** with this crew.

Sorry, I had to look up what you were asking. Part of the problem, is who you're asking. There's nobody from BE Bearings on this forum. My company sells their parts here, but I can't answer their questions at least not this one. I suggest you contact BE Bearings directly to ask your questions.

[jcolley]

Originally Posted by ksteckba

No not really. My interest is how the clearance (and its variation circumferentially) changes throughout the range of operating temperatures seen by this engine (and for each different bearing type). One of the reasons for my curiosity is that the forum is always speaking about excessive wear during very cold temperatures, yet we see many failures in hot climates.

I'll take a stab at it, if my logic is incorrect, someone please correct me.

The association of cold temps to wear is not a function of oil clearance so much as oil flow at startup before the bearing reaches its normal operating mode (fluid film) and is still establishing that.

This is where coatings and the delta of hardness between Babbitt layer and journal are concerned. Once oil pressure has built up and oil begins to flow through the bearing interface, the two surfaces are no longer in contact and material hardnesses are irrelevant.

I think those who are concerned of cold temperatures focus on thinner oils and getting oil to flow faster at startup in cold temperatures.

I personally don't think it's as big a factor as some. It's reasonably cold here in Maine and I do a lot of bearing replacements from cars all over New England. I have also had cars brought to me from FL, CA, TX, PA, etc and for preventive replacements and full rebuilds and I can't say I've noticed any difference at all in the wear on the bearings associated with locale.

Any difference in oil clearance vs temperature of OEM vs BE bearings would be a function of the thermal expansion rates of dissimilar metals on some very thin pieces. Given the BE bearings are a tri-metal design, the same as the original 702-703 bearings, I can't see any reason the clearance variation due to thermal effects would be any different. Now, with the change to the 702/703 bearings, the difference in shell materials could play into that.

[BMRLVR]

Originally Posted by jcolley

I'll take a stab at it, if my logic is incorrect, someone please correct me.

The association of cold temps to wear is not a function of oil clearance so much as oil flow at startup before the bearing reaches its normal operating mode (fluid film) and is still establishing that.

This is where coatings and the delta of hardness between Babbitt layer and journal are concerned. Once oil pressure has built up and oil begins to flow through the bearing interface, the two surfaces are no longer in contact and material hardnesses are irrelevant.

I think those who are concerned of cold temperatures focus on thinner oils and getting oil to flow faster at startup in cold temperatures.

I personally don't think it's as big a factor as some. It's reasonably cold here in Maine and I do a lot of bearing replacements from cars all over New England. I have also had cars brought to me from FL, CA, TX, PA, etc and for preventive replacements and full rebuilds and I can't say I've noticed any difference at all in the wear on the bearings associated with locale.

Any difference in oil clearance vs temperature of OEM vs BE bearings would be a function of the thermal expansion rates of dissimilar metals on some very thin pieces. Given the BE bearings are a tri-metal design, the same as the original 702-703 bearings, I can't see any reason the clearance variation due to thermal effects would be any different. Now, with the change to the 702/703 bearings, the difference in shell materials could play into that.

I agree with you on this post, however, the lack of oil clearance is what is causing us issues. Yes the coating is definitely a good help on startup and during boundary lubrication situations, but proper clearance will help this more. The coating will eventually wear through if metal on metal contact occurs too much, but yes, it will definitely help on startup before oil pressure comes up.

The clearances used in the S65 limit the oil flow through the rod bearings to a level that is insufficient to cool the journals/bearings and provide a fully developed hydrodynamic state of lubrication. At the upper RPM's this lack of flow is actually causing cavitation and this is why bearing damage is occurring.

[jcolley]

Originally Posted by BMRLVR

I agree with you on this post, however, the lack of oil clearance is what is causing us issues. Yes the coating is definitely a good help on startup and during boundary lubrication situations, but proper clearance will help this more. The coating will eventually wear through if metal on metal contact occurs too much, but yes, it will definitely help on startup before oil pressure comes up.

The clearances used in the S65 limit the oil flow through the rod bearings to a level that is insufficient to cool the journals/bearings and provide a fully developed hydrodynamic state of lubrication. At the upper RPM's this lack of flow is actually causing cavitatio

Completely agreed. The engines I have built either have the damaged journals weld repaired, then ground back to OEM diameter, hardened, and use BE bearings or I have the rod journals all ground under slightly and use stock diameter (non-OEM) bearings.