Is $4000 the going rate for rod bearings?

[Charlievee]

Originally Posted by Scharbag

BMW builds cars.

There are experts in every field. And there are laws of physics. Plain and simple. Engineers can be arrogant asshats. I know. I am an engineer. Just because you think you know better than the subject matter experts, it is not always the case. And every once and a while, you learn a hard and humbling lesson.

I think this is a case where BMW has been forced to learn (hopefully) a very hard lesson.

Cheers,

You don't work in design and manufacturing do you? I do, I'm also an engineer with many decades of experience in design and manufacturing. I've managed the engineering division and a team of design and production engineers for one of the biggest name corporations that design and build machines/engines in the world. So yeah, I know engineers can be arrogant.

https://youtu.be/HY-tz064myg

They can design an engine from scratch (S65, S85) but they can't do their own bearings designs... they messed up the bearings on the E36 M3 but did so again on the next generation? They recall issues like the HPFP on the N54 but decide not to across the 7 years of production of the S65? Come on man.... are you kidding me?

To say M sport division don't have their own SME's in house is a joke right? They have engineers for everything; aerodynamics, suspension, engine, electrical, and so on. They get the cream of the crop engineers. Those guys who work for the bearing manufacturers dream of working for an organisation like M sport. They manufacture bearings; that's what they do. They do not know or have access to any of the fundamental design and testing data of the engine to say whether the clearance is appropriate or not for the engine.

Clearance and tolerance stacking is only a theory. Tolerance stacking almost a statistical improbability mind you. One that affects the rod bearings and not the mains?? Despite the same clearances, and wear that is evident on both mains and rods?

Think like an engineer if you are one... does any of that make sense to you?

[Charlievee]

Originally Posted by deansbimmer

This is misleading and discussed ad nauseam in other threads. Later bearings are just as susceptible to failure as early bearings (if not more so). Additionally, oil analysis is unable to specifically identify bearing wear in those, rendering oil tests of little use in warning owners of danger in engines with tin/aluminum bearings.

Have you ever thought that.... maybe the failures with no indication from oil analyses is due to contamination? A rather common cause of bearing failures that will happen without any indication. Except of course in the S65 where all bearing failures are somehow directly related to defective bearings 100% of the time, right?

I'm sorry but I can't take anything you post as objective information (other than looking at photos you post without context) as there is a clear conflict on interest as evidenced in this thread.

[pbonsalb]

Yes. You are adding zero new insight. Everything you have written is obvious and has been considered. I feel sorry for that guy with 6k miles on his broken S65. Must have been due to contaminated oil....

[Charlievee]

Originally Posted by pbonsalb

Yes. You are adding zero new insight. Everything you have written is obvious and has been considered. I feel sorry for that guy with 6k miles on his broken S65. Must have been due to contaminated oil....

Exactly, yet it's the same old story over and over again. Yet the obvious is always eluded by the improbable and illogical, yet profitable solution.

Not saying contamination is always the case, but it explains the cases where failures occur without copper/lead detected through an analysis. To write off the effectiveness of an oil analysis because some failures had no excess metal wear detected is not being objective. It's being biased and serving your own interests.

The fact is that the majority of engines don't fail with the wear that is observed on most bearings that are removed, and likely won't fail. This is probably due to the wear stabilizing and not getting any worse, hence no detection in the analyses. This is highly probable due to the appearance of bearings that get removed, and the occurence of failures on most of these cars.

And If this is the case, you're more than likely not going to be experiencing a failure. A spontaneous failure can likely be attributed to other factors, such as; contamination, a blocked oil bore, driver/condition related, some factor leading to oil starvation, and so on. Factors outside of the bearing wear that seems to concern everyone, and could have occurred with or without a bearing replacement.

This is also supported by the fact that main bearings apparently don't seem to cause failures despite the appearance of all the ones pulled out. It supports the validation of the observed wear on rod bearings to not be the cause of the failures.

I mean who knows, maybe the design of the oil feeds to the bearings are designed in such a way there is an increase in risk of contamination (resulting in a higher occurance of engine failures), a design that facilitates a non-typical level of hydrodynamic pressure to create and maintain a sufficient and stable oil film at high rpms on this specific motor for the OEM specified bearing clearance. I don't know, I don't trust that you know... hmm, I wonder who would know, yep, that lot that designed and produced these engines over 7 years probably do. The ones that almost certainly undertook life cycle and fatigue design calculations, translated into real world testing, and get reported data on failures and have the provisions to remedy and said issues over the many years this engine was produced.

Also, there have been cases where excess levels of copper were detected and bearings were removed to show excess wear that more likely would have eventually led to a failure. So it has helped some in the way of detecting when a replacement was more than likely necessary.

[DRLane]

Originally Posted by Charlievee

Exactly, yet it's the same old story over and over again. Yet the obvious is always eluded by the improbable and illogical, yet profitable solution.

Not saying contamination is always the case, but it explains the cases where failures occur without copper/lead detected through an analysis. To write off the effectiveness of an oil analysis because some failures had no excess metal wear detected is not being objective. It's being biased and serving your own interests.

The fact is that the majority of engines don't fail with the wear that is observed on most bearings that are removed, and likely won't fail. This is probably due to the wear stabilizing and not getting any worse, hence no detection in the analyses. This is highly probable due to the appearance of bearings that get removed, and the occurence of failures on most of these cars.

And If this is the case, you're more than likely not going to be experiencing a failure. A spontaneous failure can likely be attributed to other factors, such as; contamination, a blocked oil bore, driver/condition related, some factor leading to oil starvation, and so on. Factors outside of the bearing wear that seems to concern everyone, and could have occurred with or without a bearing replacement.

This is also supported by the fact that main bearings apparently don't seem to cause failures despite the appearance of all the ones pulled out. It supports the validation of the observed wear on rod bearings to not be the cause of the failures.

I mean who knows, maybe the design of the oil feeds to the bearings are designed in such a way there is an increase in risk of contamination (resulting in a higher occurance of engine failures), a design that facilitates a non-typical level of hydrodynamic pressure to create and maintain a sufficient and stable oil film at high rpms on this specific motor for the OEM specified bearing clearance. I don't know, I don't trust that you know... hmm, I wonder who would know, yep, that lot that designed and produced these engines over 7 years probably do. The ones that almost certainly undertook life cycle and fatigue design calculations, translated into real world testing, and get reported data on failures and have the provisions to remedy and said issues over the many years this engine was produced.

Also, there have been cases where excess levels of copper were detected and bearings were removed to show excess wear that more likely would have eventually led to a failure. So it has helped some in the way of detecting when a replacement was more than likely necessary.

Now you're responding on every rod bearing thread? Move on man. No one cares about your opinions.

Replace, don't replace. Who gives a shit...

[Charlievee]

Originally Posted by DRLane

Now you're responding on every rod bearing thread? Move on man. No one cares about your opinions.

Replace, don't replace. Who gives a shit...

Every? I've replied on two.

In any case, isn't the point of a forums to discuss issues like this? I'd love for someone to provide me with additional insight or correct me where they believe I've misunderstood or haven't made sense. Your reply isn't appreciated or neccesary.

[DRLane]

Originally Posted by Charlievee

Every? I've replied on two.

In any case, isn't the point of a forums to discuss these issues? I mean I'd love for someone to provide me with insight or correct me where they believe I've misunderstood or haven't made sense. Your reply isn't appreciated or neccesary.

Everyone that's interested has replied, hence moving from thread to thread in search of continuing the same theories. Thus the debate as gone in circles.

Most of the folks on here are going to trust those with demonstrated capacity to assist owners in resolving their Rod bearing concerns.

Everyone here gets it. You're not replacing yours. Why do you desperately need everyone's approval?

[Scharbag]

Originally Posted by Charlievee

You don't work in design and manufacturing do you? I do, I'm also an engineer with many decades of experience in design and manufacturing. I've managed the engineering division and a team of design and production engineers for one of the biggest name corporations that design and build machines/engines in the world. So yeah, I know engineers can be arrogant.

https://youtu.be/HY-tz064myg

They can design an engine from scratch (S65, S85) but they can't do their own bearings designs... they messed up the bearings on the E36 M3 but did so again on the next generation? They recall issues like the HPFP on the N54 but decide not to across the 7 years of production of the S65? Come on man.... are you kidding me?

To say M sport division don't have their own SME's in house is a joke right? They have engineers for everything; aerodynamics, suspension, engine, electrical, and so on. They get the cream of the crop engineers. Those guys who work for the bearing manufacturers dream of working for an organisation like M sport. They manufacture bearings; that's what they do. They do not know or have access to any of the fundamental design and testing data of the engine to say whether the clearance is appropriate or not for the engine.

Clearance and tolerance stacking is only a theory. Tolerance stacking almost a statistical improbability mind you. One that affects the rod bearings and not the mains?? Despite the same clearances, and wear that is evident on both mains and rods?

Think like an engineer if you are one... does any of that make sense to you?

Not sure why you are making this personal.

Sorry for derailing the thread everyone.

Happy motoring.

[Charlievee]

Originally Posted by DRLane

Everyone that's interested has replied, hence moving from thread to thread in search of continuing the same theories. Thus the debate as gone in circles.

Most of the folks on here are going to trust those with demonstrated capacity to assist owners in resolving their Rod bearing concerns.

Everyone here gets it. You're not replacing yours. Why do you desperately need everyone's approval?

I replied on this thread to present my opinion on a comment relating to bearing manufacturers knowing better than OEM. But there is nothing wrong with starting a discussion to have my queries clarified. I'm not seeking anyone's approval, but seeking out objective input to address my concerns. The previous thread was in a region specific forum which likely doesnt get much trafffic or input from the broader community.

Again, there is nothing wrong with sharing my opinions on the issue of rod bearings. You're telling me I'm not allowed to post on any rod bearing related threads now? Who the hell are you again?

[Charlievee]

Originally Posted by Scharbag

Not sure why you are making this personal.

Sorry for derailing the thread everyone.

Happy motoring.

Hows that personal? I would have appreciated your input.

But you're right, completely derailed this thread.

Sorry x 2 and I'll remove myself from this thread.

[deansbimmer]

Originally Posted by Charlievee

Have you ever thought that.... maybe the failures with no indication from oil analyses is due to contamination? A rather common cause of bearing failures that will happen without any indication. Except of course in the S65 where all bearing failures are somehow directly related to defective bearings 100% of the time, right?

I'm sorry but I can't take anything you post as objective information (other than looking at photos you post without context) as there is a clear conflict on interest as evidenced in this thread.

Defective bearings? Not necessarily, nor have I stated that bearings themselves are the cause of failures. I subscribe to the group of thought which suspects tolerance stacking is the root cause with premature S65 failures. It's the leading theory which has shown results.

You're welcome to your own opinion, obviously you don't need to believe anything I post. I've only had my hands on a couple hundred of these engines with prematurely worn or failed bearings, what could I know? There are dozens of threads and hundreds of posts you can peruse to compare my viewpoint with documentation from industry leaders like Clevite, King, ACL, Dinan, etc.

No other BMW engine suffers from such high bearing failure rates. Did you know that the S65 has one of the tightest bearing clearance specification in the industry (and from any marque for that matter) reference data compiled HERE. No, it must be that S65 owners are just the worst in the industry at oil changes and warmup procedures.

Every week or two we get another poster in here with the conspiracy theory that all shop owners and bearing manufacturers are out to get rich off of this so we can't believe what they have to say. Should we experts not post our findings? Who do you think knows most about the topic? Hobbyists perusing pages from Google and reposting what they heard from a friend, or the shop owners and bearing engineers who specialize in the field and work in it everyday? Sure, BMW knows the most, and without a doubt they know how to build engines, but do you see their engineers posting here (or anywhere) to educate us on why they settled on their clearances? (Which were just officially released mid 2019 btw.)

If we experts don't post in here, then it's just the blind leading the blind. At some point, we won't bother to take the time. We're just too darn busy rebuilding blown S65 engines and scolding their owners for not changing their oil sooner.

[Bartledoo]

I'm late to the party, but Group 2 is overpriced as hell, and they will go over quoted hours for simple stuff (like subframe bushings) that they've had experience doing before.

[cjm41]

Saw a rod bearing thread, just popped in for the drama.

[Charlievee]

Originally Posted by deansbimmer

Defective bearings? Not necessarily, nor have I stated that bearings themselves are the cause of failures. I subscribe to the group of thought which suspects tolerance stacking is the root cause with premature S65 failures. It's the leading theory which has shown results.

Could you send some links I could look at? Tolerance stacking towards one end across all components is almost a statistical improbability. I'd like to see how the tolerance stacking theory has been modelled, and to see any said such "results" you're referring to.

Would you agree that the wear that is exhibited by most rod bearings that are pulled out will likely not result in engine failure?

Originally Posted by deansbimmer

You're welcome to your own opinion, obviously you don't need to believe anything I post. I've only had my hands on a couple hundred of these engines with prematurely worn or failed bearings, what could I know? There are dozens of threads and hundreds of posts you can peruse to compare my viewpoint with documentation from industry leaders like Clevite, King, ACL, Dinan, etc.

Point still remains, a bearing manufacturer or mechanic does not know better than those who have designed and manufactured the engine.

Originally Posted by deansbimmer

No other BMW engine suffers from such high bearing failure rates. Did you know that the S65 has one of the tightest bearing clearance specification in the industry (and from any marque for that matter) reference data compiled HERE. No, it must be that S65 owners are just the worst in the industry at oil changes and warmup procedures.

Even worse than early model S54's? Rod bearing changes are routine maintenance on those cars. You are much less likely to get away with not doing a bearing change on them. You're almost certain to walk away without issues not doing one on the S65. As I'm sure you know, not only do the S54 have clearance issues, but the width of S54 rod bearings are too narrow with exacerbates the issue.

Yes, there are tight clearances. Are they too tight? Your answer to that is subjective. Because they are as intended by the engine manufacturer. To believe a bearing manufacturer knows better is believing the tail wags the dog.

Originally Posted by deansbimmer

Every week or two we get another poster in here with the conspiracy theory that all shop owners and bearing manufacturers are out to get rich off of this so we can't believe what they have to say. Should we experts not post our findings? Who do you think knows most about the topic? Hobbyists perusing pages from Google and reposting what they heard from a friend, or the shop owners and bearing engineers who specialize in the field and work in it everyday? Sure, BMW knows the most, and without a doubt they know how to build engines, but do you see their engineers posting here (or anywhere) to educate us on why they settled on their clearances? (Which were just officially released mid 2019 btw.)

If we experts don't post in here, then it's just the blind leading the blind. At some point, we won't bother to take the time. We're just too darn busy rebuilding blown S65 engines and scolding their owners for not changing their oil sooner.

Post your findings by all means (be great if you could keep it non-biased and factual without opinions), I'm not saying you dont add value because I'm sure you have a wealth of knowledge on the subject you can contribute. To be quite honest I'm blown away by how you tried to get a sale in the open public forum. It boggles the mind. How can anything you post be considered objective if theres a clear conflict of interest?

[Charlievee]

Originally Posted by cjm41

Saw a rod bearing thread, just popped in for the drama.

[pbonsalb]

Yes, we have another new guy asking old questions. I don’t know how deansbimmer manages the patience to educate those who won’t learn for themselves.

[deansbimmer]

Originally Posted by Charlievee

Could you send some links I could look at? Tolerance stacking towards one end across all components is almost a statistical improbability. I'd like to see how the tolerance stacking theory has been modelled, and to see any said such "results" you're referring to.

Would you agree that the wear that is exhibited by most rod bearings that are pulled out will likely not result in engine failure?

No, you cannot assert that, and neither can anyone else. Otherwise, we would need to know exactly what failed bearings looked like immediately before disaster. Again, impossible.

Originally Posted by Charlievee

Point still remains, a bearing manufacturer or mechanic does not know better than those who have designed and manufactured the engine.

I might disagree with this. BMW contracts with experts for almost every aspect of their production. From various third party engineering firms for final analyses to various manufacturers when designing components and systems. Pierburg for pumps, Bosch for various electronics, Lear for circuits, Glyco or Clevite for bearings, etc. BMW knows they cannot be experts in everything, and do not have the bandwidth to engineer and assess from A-Z the hundreds of thousands of components required for their ever-changing lineup. In many cases BMW will simply provide a list of requirements or specifications to a manufacturer and leave the rest up to the third party manufacturer, but BMW has and will make occasional mistakes.

Originally Posted by Charlievee

Even worse than early model S54's? Rod bearing changes are routine maintenance on those cars. You are much less likely to get away with not doing a bearing change on them. You're almost certain to walk away without issues not doing one on the S65. As I'm sure you know, not only do the S54 have clearance issues, but the width of S54 rod bearings are too narrow with exacerbates the issue.

Yes, there are tight clearances. Are they too tight? Your answer to that is subjective. Because they are as intended by the engine manufacturer. To believe a bearing manufacturer knows better is believing the tail wags the dog.

Yes, from what I've seen, worse than the S54. Obviously that will be skewed by the fact that the S54 fell under recall and the S65 hasn't (and there is a class action lawsuit pending). S54's were starting to be problems in the early days of the internet, before social media, so they received less publicity. Many failed S54 were handled quietly at dealers, same as S65's. Nobody knows true failure numbers, not even BMW. Additionally, many engine builders would suggest that the S65 rod journal is inadequate.

Originally Posted by Charlievee

Post your findings by all means (be great if you could keep it non-biased and factual without opinions), I'm not saying you dont add value because I'm sure you have a wealth of knowledge on the subject you can contribute. To be quite honest I'm blown away by how you tried to get a sale in the open public forum. It boggles the mind. How can anything you post be considered objective if theres a clear conflict of interest?

I've posted in hundreds of various threads over the years. I'm not going to repeatedly repost the volumes of information every time a newcomer demands to be spoon fed the existing information. And yes, as a supporting vendor I pay a lot of money every month to be entitle to commercial advertising. My monetary contributions help keep the forum online for free users like you. 08-13 M3 are my area of expertise so it should not "boggle your mind" that I am usually found in these forums or that I advertise services that I specialize in when threads are started requesting info on pricing etc.

I suspect if BMW themselves were in here giving us the information we want, you would condemn it as advertising for the sale of new cars, service, or parts... In this topic of bearing wear, results, and proof of fix, much of it by nature will be opinionated, biased, or incomplete. It's always changing as long as the engines are accruing mileage. It's the responsibility of the reader to dissect it, assess the background and expertise of the poster, and decide whether or not it's based in truth.

[Scharbag]

Originally Posted by Charlievee

Tolerance stacking towards one end across all components is almost a statistical improbability.

Umm... Winning the lottery is a statistical improbability. But most lotteries have a winner. Given BMW chose to produce 1 shell and allowed a fairly wide manufacturing tolerance for rods, cranks and shells, there is a non-trivial probability that a large crank, small rod and thick shell will be assembled in an engine. This could result in a clearance of ~ as low as 0.00029"/" (088/089) or 0.00056"/" (702/703) given the data collected to date. Statistics is a bitch.

Originally Posted by Charlievee

Point still remains, a bearing manufacturer or mechanic does not know better than those who have designed and manufactured the engine.

I would disagree. As has been said, all large manufactures lean on experts to assist with the whole package. There is simply just too much for a single company to know when building a car.

Originally Posted by Charlievee

Yes, there are tight clearances. Are they too tight? Your answer to that is subjective. Because they are as intended by the engine manufacturer. To believe a bearing manufacturer knows better is believing the tail wags the dog.

Every bearing vendor that I have found stipulates a minimum of 0.001"/" of clearance for high performance engines. BMW specified less than this. I would argue that Clevite, King, ACL and Glyco know more about bearings than BMW does. Just like I would expect Micheline knows more about tires than BMW does.

Originally Posted by Charlievee

Post your findings by all means (be great if you could keep it non-biased and factual without opinions), I'm not saying you dont add value because I'm sure you have a wealth of knowledge on the subject you can contribute. To be quite honest I'm blown away by how you tried to get a sale in the open public forum. It boggles the mind. How can anything you post be considered objective if theres a clear conflict of interest?

It is unfortunate that this is again becoming personal. Posts such as yours above are why experts stop contributing to this forum. They do not need to share their knowledge with us. They choose to do so for the benefit of all forum members. deansbimmer presents good, objective information backed by demonstrable results. Presenting facts does not cause a conflict of interest and I am unsure how you arrived at that conclusion.

Happy Sunday.

[Richneerd]

Got mine changed by local board members here in California Bay Area. Mine were pretty worn on original RB's when the car was built.

I got a big laundry list knocked out at the same time.

RB Replacement
Engine Mounts
Valve cover gaskets
Oil pan gaskets
Spark Plug tubs and new spark plugs
New valve cover bolts
New crankcase valve seals
Transmission flush and fix leak
Oil Change

Around 3K total for labor and parts.

Currently at 130k miles, here goes for another 130k!

See you guys on the road!

[shimmy23]

Great price for all that work

[SoCalRPM]

To the OP's question: No.

[Charlievee]

Originally Posted by deansbimmer

No, you cannot assert that, and neither can anyone else. Otherwise, we would need to know exactly what failed bearings looked like immediately before disaster. Again, impossible.

I said “will likely”, not “definitely”. Since most engines do not fail, and the bearings almost always look like they have a similar pattern of wear. Isn’t it reasonable to say that pattern of wear observed is unlikely to result in engine failures?

The bearings are designed to wear. They are a sacrificial component. It would be very well likely that the wear pattern was accepted by BMW after testing/tear down inspections.

Originally Posted by deansbimmer

I might disagree with this. BMW contracts with experts for almost every aspect of their production. From various third party engineering firms for final analyses to various manufacturers when designing components and systems. Pierburg for pumps, Bosch for various electronics, Lear for circuits, Glyco or Clevite for bearings, etc. BMW knows they cannot be experts in everything, and do not have the bandwidth to engineer and assess from A-Z the hundreds of thousands of components required for their ever-changing lineup. In many cases BMW will simply provide a list of requirements or specifications to a manufacturer and leave the rest up to the third party manufacturer, but BMW has and will make occasional mistakes.

They design the engine as an assembly. The components that make up the assembly are designed, and specifications are provided to the manufacturers to produce. A lot of these bearings manufacturers produce bearings not knowing where or how they are used (because they make bearings, not design engines). Have you seen a manufacturing drawing? They don’t specify why they set certain dimensions or tolerances, because they are specified from design/calculations of an assembly. They don’t just willy nilly add random spec tolerances and dimensions or explain to every tom, dick and harry how they designed their engines and have come up with these dimensions. I’m speaking from experience working in the design and manufacturing industry. Not saying this is what BMW do exactly, but it’ll be pretty much what they do.

Originally Posted by deansbimmer

Yes, from what I've seen, worse than the S54. Obviously that will be skewed by the fact that the S54 fell under recall and the S65 hasn't (and there is a class action lawsuit pending). S54's were starting to be problems in the early days of the internet, before social media, so they received less publicity. Many failed S54 were handled quietly at dealers, same as S65's. Nobody knows true failure numbers, not even BMW. Additionally, many engine builders would suggest that the S65 rod journal is inadequate.

Sentiments on that are quite vastly different to anyone with knowledge or experience with the S54. If we’re covering only ‘07+ engines, we’re not covering many are we?

Even to consider that BMW got the spec so wrong on the rod bearings again on the next generation of the car that had the issue, is quite a hard pill to swallow. Considering the 190 known failures of the 64,000 produced (0.3%). It’s no doubt a low percentage, so low in fact that quite a lot of people who talk with dealerships will tell you the dealerships say they have had no experience with failed S65’s due to rod bearings. Considering also that not 100% of these failures will be due to the rod bearings as some could be due to other factors (unless you believe no other car/engine experiences bearing failures). Obviously there will be a few that go by unreported, but really, how prevalent could the rod bearing issue be for the S65 considering this?

Originally Posted by deansbimmer

I've posted in hundreds of various threads over the years. I'm not going to repeatedly repost the volumes of information every time a newcomer demands to be spoon fed the existing information. And yes, as a supporting vendor I pay a lot of money every month to be entitle to commercial advertising. My monetary contributions help keep the forum online for free users like you. 08-13 M3 are my area of expertise so it should not "boggle your mind" that I am usually found in these forums or that I advertise services that I specialize in when threads are started requesting info on pricing etc.

I joined this board to follow the rod bearing issue. I’m across the latest on the bearing issues; I’m across the original posts reporting when Van Dyne flagged it, to when the class action started till where it seems to have halted due to what some suspect as a NDA payout or the death of a plaintiff, to the latest TIS by BMW on connecting rods and bearings which show clearances. I’m not asking for new information, I’m just connecting dots and asking for some clarification.

I suppose I work in a different industry where that sort of practice is considered unethical. But if people around here can accept your judgements knowing they potentially could be influenced by financial interests, then so be it. I have nothing more to add on that and will keep my own boggles to myself. Thanks for clarifying (and also for your monetary contributions to keep the forum online for free users like me?) I mean it wouldn’t be much of a forum/community/network without users like me, and you reap the commerical benefits of being a supporting vendor... but I digress.

Originally Posted by deansbimmer

In this topic of bearing wear, results, and proof of fix, much of it by nature will be opinionated, biased, or incomplete. It's always changing as long as the engines are accruing mileage. It's the responsibility of the reader to dissect it, assess the background and expertise of the poster, and decide whether or not it's based in truth.

Agreed. The interpretation of the wear is very subjective. In an ideal world, a reader will do their diligence, but in most cases a lot of the facts are convoluted by opinions masked by a sea of information in the form of technical jargon. So easier said than done.

Originally Posted by Scharbag

Umm... Winning the lottery is a statistical improbability. But most lotteries have a winner. Given BMW chose to produce 1 shell and allowed a fairly wide manufacturing tolerance for rods, cranks and shells, there is a non-trivial probability that a large crank, small rod and thick shell will be assembled in an engine. This could result in a clearance of ~ as low as 0.00029"/" (088/089) or 0.00056"/" (702/703) given the data collected to date. Statistics is a bitch.

That’s right, but that would make the incidence of a failure as unlikely as winning the lottery. I like those odds. A tolerance stack model would have been used to analyze the variation in distribution across every component to provide an acceptable assembly measurement. There will be occurrences of where tolerances will stack, but it’s cheaper to accept these outliers than spec very tight tolerances for manufacturing which can significantly increase the costs of production. Which is the case if you do specify tolerances to prevent a worse case tolerance stack, but it’s just not economical to do.

Originally Posted by Scharbag

I would disagree. As has been said, all large manufactures lean on experts to assist with the whole package. There is simply just too much for a single company to know when building a car.

Refer to above.

Originally Posted by Scharbag

Every bearing vendor that I have found stipulates a minimum of 0.001"/" of clearance for high performance engines. BMW specified less than this. I would argue that Clevite, King, ACL and Glyco know more about bearings than BMW does. Just like I would expect Micheline knows more about tires than BMW does.

The difference between bearing and tires is that the bearings are a critical component of an assembly of critical moving parts. You cannot consider just a bearing design without all other factors. You can be an expert in making keyboards, but that doesn’t mean you understand how the motherboard processes the input. You just make sure the keyboard outputs the correct signal and the rest outside your expertise can be considered a black box.

I think my point is here, you don’t design the engine around the bearing. The bearing is designed around the engine. Who else knows better than the engine designer? How can you reasonably say a bearing manufacturing can know what bearing clearances to specify for an engine they have no data on?

Originally Posted by Scharbag

It is unfortunate that this is again becoming personal. Posts such as yours above are why experts stop contributing to this forum. They do not need to share their knowledge with us. They choose to do so for the benefit of all forum members. deansbimmer presents good, objective information backed by demonstrable results. Presenting facts does not cause a conflict of interest and I am unsure how you arrived at that conclusion.

Happy Sunday.

I don’t even understand how that is personal; Just because a person becomes the subject matter, it doesn’t follow the idiom of having “made it personal”.

You do realize there is a benefit on his end also? The benefit which creates the conflict of interest. As I said earlier, it seems to be accepted around here, so it is what it is.