Official S65 Bearing Specification/Clearance Wiki

[regular guy]

Originally Posted by Malloy

BTW VAC has already developed bearings with Clevite and they are in stock. Just sayin.

Originally Posted by Malloy

Yea, def sure.

They posted them on Facebook, but they don't seem to be on their website. I know Tony has a long relationship with the Clevite guys and this was planned for a while.

Today I got to the bottom of this. I called VAC and spoke to the engine guy. He insisted they did not have any custom made bearings and insisted they use OE bearings and have them coated. I read to him these comments and he was saying the people who wrote them were wrong. He also said the Facebook guy doesn't know cars and probably posted wrong information without knowing it. However...

I kept asking challenge questions. In fact, I asked challenge questions for 20 minutes. I told him that the post above was very specific, and I usually believe comments that come with such great specificity. He eventually remembers they're no longer buying from BMW, and that's probably what people are talking about. I challenged again. I asked how could you buy from anybody besides BMW when Clevite (the only other supplier) stopped production of S65 rod bearings 4 years ago. That got him stumped enough that he promised to go ask somebody else (the owner?) and get back to me because he knew they were buying from Clevite, not BMW.

Engine guy calls me back a few minutes later and says it's true...they did contract with Clevite to make some custom rod bearings. The new bearings, as he explained, were designed with 0.0005 inch extra clearance. VAC still adds the Calico coating, which he acknowledged takes up the extra 0.0005 inch -- returning the new bearings back to stock clearance.

So the bearings start life with 0.0005 inch extra clearance, have Calico coating added (which reduces by 0.0005 inch), and you end up with factory rod bearing clearance again.

These new bearings are Clevite Tri-Metal bearings, with lead-copper and Calico coating over the top. This means you will get the benefit of tracking lead in your Blackstone oil reports again (with these bearings).

In my opinion, this is a great new development for the market. VAC is first to market with a replacement bearing and coating over the top. This will get your engine back to the softer lead-copper bearings than the newer tin/aluminum 702/703's. Anybody who is replacing bearings right about now, and doesn't really think clearance is an issue, then these are the best choice you can make (IMO). I wouldn't use the OEM bearings under any circumstances when these are now available. Caveat: I'm assuming they don't go back to the original 088/089 clearance. If they do, then I might have to re-think this.

So what does this do for the extra clearance bearings we've been talking about making? Short answer: nothing. I spoke to the engineering and business guys behind the extra clearance bearing today and explained this development. I got a very simple answer:

"We're doing it better in every way we can think of; we've got better designers, we've got better methods, we're adding the correct amount of clearance; we're using a far superior coating than CT-1, and we will open up our testing data and make everything available once the time is right (gigabytes of data). Basically, there's nothing here that will stop us from moving forward."

I think VAC's entry into this will put pricing pressure on these business owners (that's a good thing IMO). I like VAC in the market as well because now the market can decide which bearing they want: custom lead-copper bearings factory clearance and CT-1 coating, or custom lead-copper bearings with extra clearance with better coating and gigabytes of test results available to back it up. It's a win-win for the market IMO.

Don't be surprised if you see pictures and measurements of these new bearings very soon.

[kawasaki00]

Originally Posted by regular guy

In my opinion, this is a great new development for the market. VAC is first to market with a replacement bearing and coating over the top. This will get your engine back to the softer lead-copper bearings than the newer tin/aluminum 702/703's. Anybody who is replacing bearings right about now, and doesn't really think clearance is an issue, then these are the best choice you can make (IMO). I wouldn't use the OEM bearings under any circumstances when these are now available. Caveat: I'm assuming they don't go back to the original 088/089 clearance. If they do, then I might have to re-think this.

So what does this do for the extra clearance bearings we've been talking about making? Short answer: nothing. I spoke to the engineering and business guys behind the extra clearance bearing today and explained this development. I got a very simple answer:

"We're doing it better in every way we can think of; we've got better designers, we've got better methods, we're adding the correct amount of clearance; we're using a far superior coating than CT-1, and we will open up our testing data and make everything available once the time is right (gigabytes of data). Basically, there's nothing here that will stop us from moving forward."

I think VAC's entry into this will put pricing pressure on these business owners (that's a good thing IMO). I like VAC in the market as well because now the market can decide which bearing they want: custom lead-copper bearings factory clearance and CT-1 coating, or custom lead-copper bearings with extra clearance with better coating and gigabytes of test results available to back it up. It's a win-win for the market IMO.

Don't be surprised if you see pictures and measurements of these new bearings very soon.

[e92zero]

Originally Posted by regular guy

Today I got to the bottom of this. I called VAC and spoke to the engine guy. He insisted they did not have any custom made bearings and insisted they use OE bearings and have them coated. I read to him these comments and he was saying the people who wrote them were wrong. He also said the Facebook guy doesn't know cars and probably posted wrong information without knowing it. However...

I kept asking challenge questions. In fact, I asked challenge questions for 20 minutes. I told him that the post above was very specific, and I usually believe comments that come with such great specificity. He eventually remembers they're no longer buying from BMW, and that's probably what people are talking about. I challenged again. I asked how could you buy from anybody besides BMW when Clevite (the only other supplier) stopped production of S65 rod bearings 4 years ago. That got him stumped enough that he promised to go ask somebody else (the owner?) and get back to me because he knew they were buying from Clevite, not BMW.

Engine guy calls me back a few minutes later and says it's true...they did contract with Clevite to make some custom rod bearings. The new bearings, as he explained, were designed with 0.0005 inch extra clearance. VAC still adds the Calico coating, which he acknowledged takes up the extra 0.0005 inch -- returning the new bearings back to stock clearance.

So the bearings start life with 0.0005 inch extra clearance, have Calico coating added (which reduces by 0.0005 inch), and you end up with factory rod bearing clearance again.

These new bearings are Clevite Tri-Metal bearings, with lead-copper and Calico coating over the top. This means you will get the benefit of tracking lead in your Blackstone oil reports again (with these bearings).

In my opinion, this is a great new development for the market. VAC is first to market with a replacement bearing and coating over the top. This will get your engine back to the softer lead-copper bearings than the newer tin/aluminum 702/703's. Anybody who is replacing bearings right about now, and doesn't really think clearance is an issue, then these are the best choice you can make (IMO). I wouldn't use the OEM bearings under any circumstances when these are now available. Caveat: I'm assuming they don't go back to the original 088/089 clearance. If they do, then I might have to re-think this.

So what does this do for the extra clearance bearings we've been talking about making? Short answer: nothing. I spoke to the engineering and business guys behind the extra clearance bearing today and explained this development. I got a very simple answer:

"We're doing it better in every way we can think of; we've got better designers, we've got better methods, we're adding the correct amount of clearance; we're using a far superior coating than CT-1, and we will open up our testing data and make everything available once the time is right (gigabytes of data). Basically, there's nothing here that will stop us from moving forward."

I think VAC's entry into this will put pricing pressure on these business owners (that's a good thing IMO). I like VAC in the market as well because now the market can decide which bearing they want: custom lead-copper bearings factory clearance and CT-1 coating, or custom lead-copper bearings with extra clearance with better coating and gigabytes of test results available to back it up. It's a win-win for the market IMO.

Don't be surprised if you see pictures and measurements of these new bearings very soon.

This is interesting and good news for us end users. How long ago did these customer bearing from VAC with the Calico coating hit the market? Is there a way to find out or confirm if the VAC coated bearing that showed no sign of wears from this thread

http://www.m3post.com/forums/showthread.php?t=1073979

are these customer one from VAC?

Thanks again for all the effort put into this.

[regular guy]

Originally Posted by e92zero

This is interesting and good news for us end users. How long ago did these customer bearing from VAC with the Calico coating hit the market? Is there a way to find out or confirm if the VAC coated bearing that showed no sign of wears from this thread

http://www.m3post.com/forums/showthread.php?t=1073979

are these customer one from VAC?

The announcement was made on the VAC facebook page on Feb-10, 2015 (one month ago). But that doesn't mean much, they could have been released much sooner. It would be real easy to tell by looking at the backs of those bearings from Malek. If they're stamped with 702/703 then they're factory bearings. If they don't have 702/703 stamped on them, then they're something else. I hope to have a set of these new bearings very soon. Then I will be able to see what's stamped on the back side and compare with Malek. Malek's customer had 30,000 miles, and that's at least a year of driving. So hard for me to see how VAC would have had these for so long and nobody knowing about it. Even their own engine guy didn't know about them; which may seem strange, but not totally unexplainable given he would rarely ever look at the stamps on the back, and they measure same as stock anyways.

Here's the link to the VAC announcement:
https://www.facebook.com/vacmotorspo...883169/?type=1

Thanks again for all the effort put into this.

Hey, no problem. I can't wait to hear the crickets.

[SenorFunkyPants]

Originally Posted by Yellow Snow

I can't really see how it can be tolerance stacking. The crank and rod sizes are all checking in at around mid limit. None at all are noted as being anywhere near the outer limits to cause stacking.

Not sure about bearing thickness though but I would imagine they are very consistent as well.

Actually I think you might have something.
Variations in bearing thickness is a far better fit than a simple design error.
First and foremost it means BMW aren't stupid. ie a blueprinted S65 engine running under ideal conditions would be good for 100s of 1000s of miles.
It accounts for:
Why BMW didn't change the clearance spec when deriving the S65 from the S85.
That BMW never made a simple cost free bearing clearance spec change.
Why ~98.5% of cars are still running.
A lot of engines can see very high mileages.
Failures tend to occur more at lows miles than high miles.
It also can account for why the bearing spec change at late 2010 caused a rise in low mileage failures. It included a manufacturer change - presenting the possibility that the new supplier (not Clevite IIUC) were even less adapt at keeping to the required tolerance.

I still believe that long term low level detonation is a good fit for the accelerated wear seen on the top shell of bearings seen when removed from running cars.

I'm out for the day so I'll have to come back to this later and finish this off.

[Mvy]

Originally Posted by regular guy

The new bearings, as he explained, were designed with 0.0005 inch extra clearance. VAC still adds the Calico coating, which he acknowledged takes up the extra 0.0005 inch -- returning the new bearings back to stock clearance.

This is good news and is consistent with what VAC told my local indy shop 6 months ago. My indy shop did hand measure the bearings (not as accurately as RG or K did) but enough to tell that it was likely no thicker than factory ones. I guess we can now just keep watch on this and see what happens as we put miles on these bearings. Im going with oil change frequency being a major factor in bearing wear and hope with 5k oil changes ill be in good shape well over 100k miles.

[regular guy]

Originally Posted by SenorFunkyPants

Actually I think you might have something.
Variations in bearing thickness is a far better fit than a simple design error.
First and foremost it means BMW aren't stupid. ie a blueprinted S65 engine running under ideal conditions would be good for 100s of 1000s of miles.
It accounts for:
Why BMW didn't change the clearance spec when deriving the S65 from the S85.
That BMW never made a simple cost free bearing clearance spec change.
Why ~98.5% of cars are still running.
A lot of engines can see very high mileages.
Failures tend to occur more at lows miles than high miles.
It also can account for why the bearing spec change at late 2010 caused a rise in low mileage failures. It included a manufacturer change - presenting the possibility that the new supplier (not Clevite IIUC) were even less adapt at keeping to the required tolerance.

I still believe that long term low level detonation is a good fit for the accelerated wear seen on the top shell of bearings seen when removed from running cars.

I'm out for the day so I'll have to come back to this later and finish this off.

Let me be the first to point this out while the other two aren't rushing in here to do the same. What you're describing is called "tolerance stacking." Whether it's due to rod journal thickness variance, rod bore diameter variance, or rod bearing thickness variance, it all adds up and is called the same thing: tolerance stacking.

Manufacturers design maximum and minimum allowed variance just so tolerance stacking won't lead to a failure. Whether it's too little clearance, or the specification on variance are too liberal, both describe a manufacturing design error (your words, not mine). There's no way to spin out of that.

If you want to see how bearing thickness, journal size, rod bore diameter, and clearance are all related (or possibly not), then you can look on page-1 of this thread, where all of the data, with measurements for each, including bearing thickness for each bearing shell is posted.

[Obioban]

Originally Posted by Mvy

This is good news and is consistent with what VAC told my local indy shop 6 months ago. My indy shop did hand measure the bearings (not as accurately as RG or K did) but enough to tell that it was likely no thicker than factory ones. I guess we can now just keep watch on this and see what happens as we put miles on these bearings. Im going with oil change frequency being a major factor in bearing wear and hope with 5k oil changes ill be in good shape well over 100k miles.

It's been pretty throughly established that there is no correlation with oil change interval.

Not that I'm saying you shouldn't do it-- I do, too. Just that isn't not the problem or solution here.

[Malek@MRF]

Originally Posted by regular guy

The announcement was made on the VAC facebook page on Feb-10, 2015 (one month ago). But that doesn't mean much, they could have been released much sooner. It would be real easy to tell by looking at the backs of those bearings from Malek. If they're stamped with 702/703 then they're factory bearings. If they don't have 702/703 stamped on them, then they're something else. I hope to have a set of these new bearings very soon. Then I will be able to see what's stamped on the back side and compare with Malek. Malek's customer had 30,000 miles, and that's at least a year of driving. So hard for me to see how VAC would have had these for so long and nobody knowing about it. Even their own engine guy didn't know about them; which may seem strange, but not totally unexplainable given he would rarely ever look at the stamps on the back, and they measure same as stock anyways.

Here's the link to the VAC announcement:
https://www.facebook.com/vacmotorspo...883169/?type=1



Hey, no problem. I can't wait to hear the crickets.

Responded to your email.

The bearings from that engine in discussion are indeed 702/703 bearings. Every coated bearing set I have seen from VAC/Calico have been the OEM coated bearings. My connections at VAC tell me the same.

I have multiple sets of the VAC/Calico bearings showing up at the shop early this week. I will verify for everyone whether they are the 702/703's, however I suspect they are as they always have been.

If anyone is prepared to have the pot stirred and remain civil, I can share the connecting rod bolt (ARP vs. OEM) bearing clearance data.

[regular guy]

Originally Posted by Malek@MRF

Responded to your email.

The bearings from that engine in discussion are indeed 702/703 bearings. Every coated bearing set I have seen from VAC/Calico have been the OEM coated bearings. My connections at VAC tell me the same.

I have multiple sets of the VAC/Calico bearings showing up at the shop early this week. I will verify for everyone whether they are the 702/703's, however I suspect they are as they always have been.

If anyone is prepared to have the pot stirred and remain civil, I can share the connecting rod bolt (ARP vs. OEM) bearing clearance data.

Malek, I beat you to it. I have the new VAC bearings and they are indeed custom Clevite bearings.

Just one question about your rod bearing measurements of OEM vs. ARP. Did you use new OEM bolts when you did it? If not, all bets are off. When I first bought my new rod bolts for all these measurements, I still had used bolts laying around and installed in the rods. I took a set of measurements with the used bolts and couldn't get consistent readings across the set. Once I switched to new OEM bolts, everything was find and the readings were very consistent.

I'm in the process of measuring these new VAC bearings now. I went out and bought new bolts just to make sure it was right.

Here's a sneak peek:

[regular guy]

Here's a brief update. I just finished measuring the bearing thicknesses. I realize I can't just subtract the size of the 702/703's and come up with a difference in clearance. But if I did, and if that was valid, then these would give an extra 0.00050 inch AFTER the coating, not before. Just from what I'm seeing so far, it looks like these will give some extra clearance. It will be a small amount, but it will be extra clearance over 702/703.

But nothing is final until I finish all the measurements. That will take a while. I have a new set of rod bolts to stretch in before I can measure.

[regular guy]

Rod bolts stretched, bearings installed, ready to measure clearance and eccentricity.

[swamp2]

Originally Posted by Yellow Snow

That's interesting Swamp. Could you check my maths here please. I must have a decimal point error.

In simple form where .0000072 is the expansion coefficient of steel and 9 is the temp difference in Fahrenheit.

.0000072 x 9 = .0000648 multiplied by dia 2.0465" = .00013"(3.3 microns)

Yep, I flubbed the math. Embarrassing...

L = Linitial(1+αΔT)
α is about 7e-06 in/in degF
ΔT is 9
so L-Linitial = ΔL and that is indeed .00013 or 3.3 microns.

Thanks for the correction. No idea how I botched such a simple calculation. It wasn't typing too few/many zeros since I use scientific notation.

However, this difference is still a factor of 10 smaller than the tightest minimum Clevite rule of thumb, 7.5 tenths of a thousandth in/in which is about 1.5 thousandth.

All that being said, if BMW has a standard here of 68 degrees for measurement, that standard should be adhered to and certainly should be used for measuring all parts.

[swamp2]

Originally Posted by Malek@MRF

If anyone is prepared to have the pot stirred and remain civil, I can share the connecting rod bolt (ARP vs. OEM) bearing clearance data.

Do you mean you have done a "perfectly" apples to apples comparison that shows different bolts (all else held constant) provide different clearances? Please "stir the pot".

[swamp2]

Originally Posted by Yellow Snow

I can't really see how it can be tolerance stacking. The crank and rod sizes are all checking in at around mid limit. None at all are noted as being anywhere near the outer limits to cause stacking.

Originally Posted by SenorFunkyPants

Actually I think you might have something. Variations in bearing thickness is a far better fit than a simple design error. First and foremost it means BMW aren't stupid.

Originally Posted by regular guy

Let me be the first to point this out while the other two aren't rushing in here to do the same. What you're describing is called "tolerance stacking." Whether it's due to rod journal thickness variance, rod bore diameter variance, or rod bearing thickness variance, it all adds up and is called the same thing: tolerance stacking.

Not sure what you (rg) mean by the first sentence but indeed all parts, dimensions and processes that create a variation in an end assemblies dimensions are part of what anyone should accept as the definition of tolerance stacking.

So SFP, here, no matter what causes a stacking problem, it doesn't really excuse BMW if they are ignorant of such an issue.

According the the data on page 1, the observed extrema of bearing clearances (both production bearings) are from 0.00105" min to 0.002 max. This is 5.3 tenths in/in up to 1 thou in/in. It is a considerable range. However, if I recall correctly the methodology included a deliberate attempt to create the widest range possible. It is entirely unknown if BMW has more control in place than this (custom part fitting though does seems unlikely). Also, I've yet to see any evidence than less than the min Clevite spec of 7.5 tenths in/in (perhaps along with 10W-60 oil) is a guaranteed "death sentence" known to produce bearing failure during low milege. It also hasn't been established if this near .001" range (5 tenths in/in) in clearance is better or worse than industry norms.

Anyway, not to beat the dead horse, I think BMW has been and is completely aware of this tolerance stacking and have some reason(s) for the selection of these dimensions. In this way, no they aren't stupid nor ignorant. If this stacking is the cause of the premature wear or failures, I suspect BMW knows what the approximate failure rate would be and are fine with it. kawasaki though has clearly stated his experience is that the entire range could be shifted up (by 5 tenths or 5 tenths in/in?) and "no one but the engine builder would ever know" (rough quote).

[regular guy]

Originally Posted by swamp2

Anyway, not to beat the dead horse, I think BMW has been and is completely aware of this tolerance stacking and have some reason(s) for the selection of these dimensions. In this way, no they aren't stupid nor ignorant. If this stacking is the cause of the premature wear or failures, I suspect BMW knows what the approximate failure rate would be and are fine with it.

I wonder how many times I've said the same exact thing only to have it ignored or twisted into something completely different. I mean really, I wonder how many times because I've said the same exact thing (with different words) many times. So feel free to keep beating away at this dead horse.

[chris719]

Of course BMW doesn't care. They didn't care to design the E36 and E46 subframes correctly either, which finally resulted in a lawsuit.

[swamp2]

Originally Posted by regular guy

I wonder how many times I've said the same exact thing only to have it ignored or twisted into something completely different. I mean really, I wonder how many times because I've said the same exact thing (with different words) many times. So feel free to keep beating away at this dead horse.

I've heard something similar from you but absolutely not the exact same thing. In particular I've never heard any acknowledgment that there may be benefits and rationale to their choice. Either way, sorry for more or less taking you side. Bitch when I do, bitch when I don't.

[swamp2]

Originally Posted by chris719

Of course BMW doesn't care. They didn't care to design the E36 and E46 subframes correctly either, which finally resulted in a lawsuit.

To be fair, there is only about 1 million shades of gray in what "correct" means. I mean, sure, most consumers expect a well designed car to last perhaps around 300k miles with no real major engine nor chassis failures. Obviously, there isn't anything even close to a warranty nor even hint of expectation that this is guaranteed. I think many E36s and E46s probably have lasted that long under that definition of "last". My own E36 M3 had some nasty recurring head cracking problems but at least one instance was due to a dishonest vendor who supplied a weld repaired head rather than a low mile/used but non weld repaired unit as we agreed upon...

[Yellow Snow]

Originally Posted by swamp2

Yep, I flubbed the math. Embarrassing...

L = Linitial(1+αΔT)
α is about 7e-06 in/in degF
ΔT is 9
so L-Linitial = ΔL and that is indeed .00013 or 3.3 microns.

Thanks for the correction. No idea how I botched such a simple calculation. It wasn't typing too few/many zeros since I use scientific notation.

However, this difference is still a factor of 10 smaller than the tightest minimum Clevite rule of thumb, 7.5 tenths of a thousandth in/in which is about 1.5 thousandth.

All that being said, if BMW has a standard here of 68 degrees for measurement, that standard should be adhered to and certainly should be used for measuring all parts.

Thanks Swamp. Glad to have the figures confirmed.

IF this was a stacking issue which I sincerely doubt, lets not forget stacking can go both ways. Fitting .00025" thinner bearings could take it past the OEM maximum clearance.

[SenorFunkyPants]

Originally Posted by swamp2

So SFP, here, no matter what causes a stacking problem, it doesn't really excuse BMW if they are ignorant of such an issue.

I think we can both be confident that BMW is well aware of the cause of most every failure of broken engines returned to them by dealers.

But that wasn't the point I was trying to make. I'll try and explain it in a better way.
The new spec bearings introduced ~ late 2010 have a bigger clearance, increased eccentricity and use materials with a higher wear resistance.
The tight bearing theory predicts better reliability for these engines.
However, look at the number of engine failures for 2007 -2010 cars versus 2011-2013 cars occurring below 40,000 miles.
2007-2010 4
2011-2013 22
[USA/Can exclude S/C cars - production numbers are similar for both sets]
Thats a pretty striking difference, especially as far more older cars will have passed 40k miles than newer ones.
The same spec crankshaft and rods are in use before and after the bearing spec change, so either the specification changes to the new lead free bearing is the cause (unlikely) or the change to a different supplier with poorer quality control is the cause (likely)....suggests that BMW produced crankshafts/rods are accurate and its the external bearing manufacturer who is introducing parts not always in tolerance, especially in later cars.

In that case ISTM that replacing rod bearings with ones that have been accurately checked to be exactly to BMW spec is the lower risk option.

[OM VT3]

Originally Posted by SenorFunkyPants

I think we can both be confident that BMW is well aware of the cause of most every failure of broken engines returned to them by dealers.

But that wasn't the point I was trying to make. I'll try and explain it in a better way.
The new spec bearings introduced ~ late 2010 have a bigger clearance, increased eccentricity and use materials with a higher wear resistance.
The tight bearing theory predicts better reliability for these engines.
However, look at the number of engine failures for 2007 -2010 cars versus 2011-2013 cars occurring below 40,000 miles.
2007-2010 4
2011-2013 22
[USA/Can exclude S/C cars - production numbers are similar for both sets]
Thats a pretty striking difference, especially as far more older cars will have passed 40k miles than newer ones.
Its the same crankshaft and rods for both sets, so either the specification changes to the new lead free bearing is the cause (unlikely) or the change to a different supplier with poorer quality control is the cause (likely)....suggests that BMW produced crankshafts/rods are accurate and its the external bearing manufacturer who is introducing parts not always in tolerance, especially in later cars.

In that case ISTM that replacing rod bearings with ones that have been accurately checked to be exactly to BMW spec is the lower risk option.

You are incorrect again there are about 3 different cranks used in the s65