Official S65 Rod Bearing Condition Example Thread

[Assimilator1]

Originally Posted by deansbimmer

Fixed the pics. They're VAC/Clevite.

So aren't these the standard bearings with their coating? So standard clearances minus a little for the coating?

Very clean bearings anyway!

*******************************
And after finally going through this whole thread! (not read it all though), a couple of interesting observations I'd like to note of all the dozens of photos posted here of RBs (I've looked at them all, obviously not including ones that now have a broken link), only 2 posts of photos of OEM RBs are shown in good condition with slight typical wear expected with any engine!
The newer Alu/tin bearings mostly seem to fair better (unless that's a limitation of just looking at photos?), although they seem to often get those dark spots from embedded debris.

With that, I want to reply/ask questions to a few people.

Why do people say the latter OEM alu/tin bearings have no extra clearance over the earlier ones when they do? At least according to the bearing wiki. The minimum variance has been increased from -0.00090" to -0.00035". (And maybe that's why they appear to fare a little better?)

Why do people say a new crank for these is ~$10k, when a quick search I did today shows them to go for about £/$3k? (not that that's cheap by any means though! ) (was I looking at old posts??).

serranot You said - I think that’s my point. If it has wear, it’s not ok. How is one supposed to know what “ok” is vs “not ok"

As far as the copper/lead bearings go, not ok is through to the copper, at this stage scouring & galling is possible & increasingly likely as more of the lead is worn away.
Ok* is where their is still lead completely covering the wearing surface, the bearing isn't at risk of imminent** failure.

*and when I say ok, I don't mean it's in normal condition for the mileage of the engine compared to engines generally. I mean it's ok for S65's & isn't in immediate danger of causing damage.
**how long is imminent? Not a foggiest lol! So whether this wear has been picked up by oil reports, or by the RBs being removed, knowing that these engines suffer from premature RB wear &/or failure it's still worth changing them then.

Originally Posted by ThatM3guy

It’s even more concerning as I am showing strong, consistently healthy oil reports and yet the bearings have wear and some have significant wear. You could argue that occurred in the first 55k, but I doubt all wear occurred then. Interesting huh?

You/we can't know that, my belief is that based on the tight clearances they're likely to start with, most of the wear occurs early on*, in your case, yes I think most of that lead was 'ground' away within it's 1st 55k miles. Otherwise the oil reports would've picked it up, although this leads on to something IamFODI said......

*I know Deansbimmer is sceptical of this idea, saying something along the lines of the babbet layer being 'ground' away like this causes damage to the remaining layer & hence faster than normal wear, (not saying he's wrong as he has vastly more experience than me on building engines ), but enough of the babbet layer could be left to account for the wide range of mileages that these engines achieve.
Both points could be right, heavy wear occurs early on and where the RB doesn't fail then, the fractional extra gap achieved & if enough of the (damaged) babbet layer is left, it keeps the engine going for (usually) several 10k's of miles, but of course if the engine is stripped down at any point after the early stages the bearings will be found to have premature wear.

Originally Posted by IamFODI

Well... yes and no.

Like most oil analysis labs, Blackstone gets its wear metals counts from ICP spectroscopy, which only catches particles up to a certain size -- and not all mechanical wear chucks out particles in that size range. Some wear modes produce bigger particles, to which ICP spectroscopy is completely blind. Furthermore, ICP-detectable particles can come from chemical processes that have nothing to do with what most people would consider mechanical wear -- processes like acid attack from overextended oil change intervals, or highly active surface chemistry from aggressive anti-wear additives in the oil. So, if you see big numbers, it's difficult or impossible to say whether they're anything to worry about. And if you see low numbers, maybe everything's fine, or maybe there's a wear mode that ICP spectroscopy can't detect. You have no idea just from looking at the report.

S65s with the original BMW rod bearings are lucky in that they sometimes produce lead and copper particles in ICP-detectable sizes when their rod bearings wear abnormally, AND they don't seem to produce ICP-detectable lead or copper in significant quantities for any other reason (barring leaded fuel or new oil cooler hardware or something). So, if you see those high numbers from one of those engines, then yeah, it's probably rod bearings. But again, if you don't see those numbers, you have no idea.

We don't know how or to what extent the updated BMW rod bearings or any aftermarket rod bearings will show wear on ICP spectroscopy, if they even do at all. Aftermarket bearing manufacturers will say they went for leaded bearings to facilitate oil analysis, but there's been no rigorous testing of that idea and the data from the field is incomplete. What little evidence we have on the updated BMW bearings is not favorable, though we don't even know what we're looking for because we don't know what they're made of.

ICP spectroscopy can be useful for tracking early-stage wear when you have a lot of background knowledge about the application in question. You have to know in advance whether and how any potential wear problems will show up on oil analysis, and you have to know about any possible sources of false-positives. Then you have to sample frequently enough to catch the wear while it's still in that early stage, before it starts producing particles too big for ICP spectroscopy to detect.

In other words, it requires a bunch of things that are difficult if not impossible for an end user running oil with unknown chemistry on a hand-built car engine with unknown metallurgy operated in the real world under uncontrolled conditions. And that's the main problem here.

It's generally assumed that frequent and regular sampling can reduce the futility of oil analysis in an application like this. That's why I'm doing it. But I'm sampling every 5k miles and using a slightly more extensive analysis package (Polaris Labs Advanced Engine Plus), and I'm not taking low numbers to mean a clean bill of health. I'm already planning to revisit my rod bearings within 60k-80k miles after the first change. What I'm looking for are signs that I might have to do them sooner, as well as signs of other kinds of trouble like fuel dilution and other contaminants -- which, by the way, is where oil analysis is truly useful in a car engine. Maybe that's another thread.

The set of oil analysis reports you had prior to changing your rod bearings wasn't so much a consistent history as a few snapshots over tens of thousands of miles. And again, that's in addition to the serious limitations of oil analysis for tracking wear.

Is what you did better than nothing? Absolutely.

Is it mysterious that oil analysis missed your rod bearing wear? Not in the least.

Ref acid attacks from extended oil changes, I think it's fair to say that with the vast majority of RB photos posted here plus the OCI info shown, bar 1, they have all changed oil under the standard interval, so this is not a likely scenario. Also, surely the oil report would find other signs of extended OCIs? (even if the oil life wasn't reported).

Re - which only catches particles up to a certain size -- and not all mechanical wear chucks out particles in that size range. Some wear modes produce bigger particles, to which ICP spectroscopy is completely blind

What wear modes? And what particle size?
Not saying you're wrong, (you seem to know something about oil analysis , where from?), just you're the 1st person I've come across whose actually given a logical plausible reason as to how the oil reports might not pick up bearing issues.

Interesting you say about sampling every 5k miles, I'm (still) in the process of looking at any S65 oil reports + photos I'm coming across, and from the small numbers I've found so far (31 to date, I'll be posting a thread about it), it seems that 5k miles is the maximum sampling interval you want to do to stand a good chance of picking up RB problems with the cu/pb bearings before damage is done to the crank.

Btw, my general position on the RB S65 problem is this, I don't question that their is a RB problem with the engine. I do question whether oil reports can miss it (although you might change my mind on that) and I think it's more likely that some people aren't using the oil sampling properly, e.g a massive mileage gap between oil analysis & RB failure or strip down, only doing 1 sample, and when stripped down some people saying the bearings are completely knackered when they're not! (primarily talking about the cu/pb bearings here), e.g not gone through to the copper (not saying that the bearings are fine either! just not imminent or near imminent failure).
And going by what I've read to date it does seem that the OEM bearing clearances are much too tight at the minimum end!

I've got a 2008 M3 with 75k miles which I bought in November, just had the oil sampled by The Oil Lab & it got a good report with 3 & 4 ppm cu & pb , oil's done 3.3k miles.
Atm I'm still looking into this issue whilst I've taken the car off the road for the winter (until April), due to cost reasons I'll only be doing a total 2k miles for my 1st yr with it, may go to 3k/yr afterwards, I plan to do a few track days each yr too.
The oil report is to see if I'll be ok for this year, so far, I believe I am! I plan to oil sample again the end of this year. If I'm 100% sure oil sampling will definitely pick up bearing issues I'll carry on doing that, but even if I'm only 99% sure I'll be changing the RBs next year (probably with ACL ones).

Hopefully I haven't overlooked an obvious points!

Originally Posted by Scharbag

.......

Also, if it were a simple $2500 engine swap, I would not worry about it regardless. Unfortunately, BMW does not have any new S65s in the warehouse because they have all been used due to the horrendous number of failed engines. Used engines are not cheap or easy to find a really good one. Rebuild costs are ridiculously expensive when done properly due to the complexity of the engine and the cost of parts. Regardless to which option you choose, the labor to replace the engine is also not cheap.

But everyone is entitled to their own opinions.

Cheers,

How do we know they don't have anymore new engines left?

[IamFODI]

Originally Posted by Assimilator1

Re - which only catches particles up to a certain size -- and not all mechanical wear chucks out particles in that size range. Some wear modes produce bigger particles, to which ICP spectroscopy is completely blind

What wear modes? And what particle size?
Not saying you're wrong, (you seem to know something about oil analysis , where from?), just you're the 1st person I've come across whose actually given a logical plausible reason as to how the oil reports might not pick up bearing issues.

There are several threads on BobIsTheOilGuy.com about this, from several years ago before most of the real experts left or stopped posting.

I can't offer a better summary than I already have because I'm FAR from an expert on this. I basically know just enough to be able to use oil analysis in a reasonable way. If you want to learn more, I'd recommend some good old-fashioned research. However, here are a few links to get you started:

This is an article on the different kinds of wear particles produced by different wear modes.

This and this are articles on oil analysis methods, which include the particle size limitations of ICP spectroscopy and some potential implications thereof.

This is essentially a marketing pamphlet so one of the examples is extreme, but it makes the point that severe mechanical problems don't always produce high numbers on a spectrographic analysis.

Originally Posted by Assimilator1

Interesting you say about sampling every 5k miles, I'm (still) in the process of looking at any S65 oil reports + photos I'm coming across, and from the small numbers I've found so far (31 to date, I'll be posting a thread about it), it seems that 5k miles is the maximum sampling interval you want to do to stand a good chance of picking up RB problems with the cu/pb bearings before damage is done to the crank.

I got the same impression.

If I could, I'd sample twice per OCI, so every 2500 miles. There's just no easy way to do that on this engine.

I guess I could just change my oil much more frequently. I just don't think the benefit would be worth the extra effort.

Originally Posted by Assimilator1

The oil report is to see if I'll be ok for this year, so far, I believe I am! I plan to oil sample again the end of this year. If I'm 100% sure oil sampling will definitely pick up bearing issues I'll carry on doing that, but even if I'm only 99% sure I'll be changing the RBs next year (probably with ACL ones).

I wouldn't even bother with oil analysis until after you change your bearings.

After that, go ahead and use it -- but keep your sampling intervals short and regular, and don't lean entirely on it to tell you when to change your bearings again (assuming you own the car that long).

[Assimilator1]

You don't have to draw your oil from the sump, you can draw it from the oil filter housing, that's what I did.

Btw, in looking into oil analysis reports+photos, so far I've found 19 that showed high lead levels & bearings were confirmed bad.
6 reports that the levels were ok, & on strip down, whilst the bearings were worn, none had gone through to the copper so hadn't failed.

6 people claimed the oil analysis had missed failed bearings, but either they just plain hadn't (weren't to copper), or the reports were done several 1000 miles before! Or the oil reports or lead & copper levels weren't even posted.
So, so far I haven't yet come across a single solid case where the oil report missed anything!
If anyone knows of some, then link me up!

[IamFODI]

Originally Posted by Assimilator1

You don't have to draw your oil from the sump, you can draw it from the oil filter housing, that's what I did.

Interesting. Didn't realize you could get enough for a sample that way.

I wonder about the integrity of the seals if the filter is removed and reinstalled, but maybe a mid-OCI filter change wouldn't suck anyway. Hmm....

How big of a sample did your lab ask for, and what kind of fluid extractor did you use?

[pbonsalb]

You usually get more oil than you want out of the filter housing. I have never not spilled some when changing the filter during an oil change. I think there is a check valve that keeps oil in the housing.

[IamFODI]

Originally Posted by pbonsalb

You usually get more oil than you want out of the filter housing. I have never not spilled some when changing the filter during an oil change. I think there is a check valve that keeps oil in the housing.

Good call.

I always pump that excess oil out of the housing when I change the oil, but for some reason I never registered just how much oil that is. Thinking about it now, I bet it's plenty for a small sample bottle...

[Assimilator1]

The Oil lab gave me a 30ml syringe & tube to suck the oil out, it took about 3 goes to fill the little bottle IIRC.
The o-rings will be fine after removing & refitting housing, as long as you don't catch it on something!, so no need to replace the filter. To reduce the amount of oil spilled, let the housing sit on the top of the threads at a slight angle (& still inside the lower housing) for about 1/2 a minute. Oh and cross your fingers the housing doesn't pull the filter out with it , as it's the filter itself that traps the oil (which is why you should remove it 1st when doing an oil change).

Incidentally I kinda found my 1st case of an oil report missing bad bearings, although the write up does indeed give the all clear, the analysis does show elevated lead & copper readings at 20 & 9ppm. The oil sample was taken 1k miles before the bearings were changed, so reasonably soon after. BUT he only had that 1 sample done (as he'd not long had the car). So that's probably the main reason it 'missed' it, although the oil had covered 3-4k miles.
So it would seem that to stand a good chance of an oil report finding bad bearings, you not only would have to consider a max test interval of 5k miles (& quite possibly less), you would have to set a far lower limit on the lead ppm than the labs set. Maybe as little as 15? With ~10ppm possibly being an early sign of trouble (assuming no leaded fuel has been used of course ).

Oh btw, re particle big sizes being missed in oil reports, it sounds like this test could catch those, but look at the price!!! That's more than the cost of ACL bearings! lol

[deansbimmer]

Originally Posted by Assimilator1

So aren't these the standard bearings with their coating? So standard clearances minus a little for the coating?

Very clean bearings anyway!

No, VAC's CLEVITE manufactured bearings are increased clearance tri-metal bearings which were designed with a greater clearance to compensate for the coating thickness. Only the earliest VAC rod bearings were OEM bearings with a coating.

And to touch on another topic you quoted...

Most users are not bearing engineers and don't understand the incredibly complex nature of their design beyond thinking a simple clearance dimension is all that's required. Take for example the attached photo from KING BEARINGS and you start to see how complex the topic becomes.

As you can see from the illustration, combustion forces concentrate wear to only a portion of the bearing. That's why we see wear footprints on worn bearing shells. Maintaining the engineered bore shape is critical to the long life of a bearing. As the bearing wears, bad things start to happen, and at a certain point of erosion when the bearing's hydrodynamic functions decline, the wear rate increases exponentially until failure. For example, here are two things that happen:

1) The soft babbit is worn away (intended not only to be a soft surface for the steel crank to ride against during low oil pressure, but also to embed foreign debris to protect the journal) and exposes a harder substrate- usually copper or aluminum alloys engineered by the bearing manufacturer. Unable to embed debris into the load area of a bearing, the journal becomes much more susceptible to instantaneous failure due to foreign matter. As engines age, components degrade, internal carbon buildup increases, maintenance declines, quality and cleanliness of engine open service declines.....this risk of foreign debris increases dramatically. With little to no ability to embed debris, the journal is t risk of the proverbial double whammy.

2) The resulting erosion of material from the precision design causes a change in bore shape. This change in bore shape has a very negative effect on the hydrodynamic function of the bearing, as you might gather from the illustration. This erosion and its resulting bore change is not "increasing clearance" in a positive way which is a commonly parroted misconception.

[Dave07997S]

Dean from my understanding, the VAC increased clearance bearings do have more clearance than OEM but just not up to the BE design clearances.

[deansbimmer]

Originally Posted by Dave07997S

Dean from my understanding, the VAC increased clearance bearings do have more clearance than OEM but just not up to the BE design clearances.

Correct. You can review official measurements from BE here:
http://wiki.rcollins.org/core/index....5_Rod_Bearings

[Assimilator1]

Re VAC bearings, ok cool, the good condition makes sense then! For some reason I thought it had the earlier shells.

Re bearing wear, I did say the 'damaged babbit', so I didn't imply it was positive wear .
Any idea how thick the babbitt layer is on a typical car engine's bearings?

[kiquos]

Hello Im new to the E92 and this Forum. Have you guys heard of a bearing failure after the bearings have been changed? Failure meaning bearing cap failure hit the block and making a hole!
thanks
P.S. changed to upgraded rod bearings specific to the S65.

[Helmsman]

Originally Posted by deansbimmer

Correct. You can review official measurements from BE here:
http://wiki.rcollins.org/core/index....5_Rod_Bearings

Deansbimmer, BEs page specifically says the VAC shells (they measure) has not increased clearance. Looking at VAC page they offer standard and .025 increased clearance. Curious on what shells you took out?

[chocstraw]

Originally Posted by Helmsman

Deansbimmer, BEs page specifically says the VAC shells (they measure) has not increased clearance. Looking at VAC page they offer standard and .025 increased clearance. Curious on what shells you took out?

I ordered VAC bearings about a week ago and the rep, Hayyan, said that they are now all increased clearance. He also said the option for “undersized” bearings is for cars with cranks that have been ground down due to journal damage. He apologized for how unclear the listing page is, and said someone should update it.

[Assimilator1]

Originally Posted by Helmsman

Deansbimmer, BEs page specifically says the VAC shells (they measure) has not increased clearance. Looking at VAC page they offer standard and .025 increased clearance. Curious on what shells you took out?

I asked him the exact same question above & he answered me .

Originally Posted by kiquos

Hello Im new to the E92 and this Forum. Have you guys heard of a bearing failure after the bearings have been changed? Failure meaning bearing cap failure hit the block and making a hole!
thanks
P.S. changed to upgraded rod bearings specific to the S65.

You're not giving us anywhere near enough info, did a bolt let go? Or did the bearing seize causing the failure? Got any pics?

Sorry to hear about your blown engine btw

[CarbonBlack88]

Well, I've seen worse but I've seen a hell of a lot better too.

Build date: February 2013; 6MT ZCP with 39k miles. Engine is stock - no tunes, never been SC'd etc.

Picked up the car in October and decided to take care of the bearings as preventative. No symptoms of trouble.

I'm the 4th owner (first owner was a lease and then two Board members) and to the best of my knowledge, the car has never been tracked nor abused.

Owner prior to me did a Blackstone report in Dec 2018. It showed no signs of danger (as expected with aluminum bearings).

Went with BE bearings and BE-ARP bolts. Also replaced the motor mounts with new Vibra Technics and went with new NGK spark plugs.

Work performed by VT Motorsports in Pleasanton. I couldn't be more happy with their service and communication throughout the process - would highly recommend them to anyone who needs RB's done in the Bay Area.





Here's a few pics that Matt sent me from the process:

[Helmsman]

Originally Posted by chocstraw

I ordered VAC bearings about a week ago and the rep, Hayyan, said that they are now all increased clearance. He also said the option for “undersized” bearings is for cars with cranks that have been ground down due to journal damage. He apologized for how unclear the listing page is, and said someone should update it.

Ah, so the undersized are oversized really... Anyways thanks for clarification. BE page still refer to the standard shell claiming not increased clearance but maybe way back when that was the case. All a bit confusing, but if I would guess its the same shell all along since they left the coated OEM. Anyway, some of them comes out in brilliant shape.

[deansbimmer]

Originally Posted by Helmsman

Deansbimmer, BEs page specifically says the VAC shells (they measure) has not increased clearance. Looking at VAC page they offer standard and .025 increased clearance. Curious on what shells you took out?

Look at the measurements and reported nominal clearances. Numbers don't lie. VAC Clevite shells yielded .0021" clearance, which is obviously greater than factory clearance, although not as open as BE. The measurements throughout that page are similar to the numbers we get on our Mitutoyo equipment.

Originally Posted by Helmsman

Ah, so the undersized are oversized really... Anyways thanks for clarification. BE page still refer to the standard shell claiming not increased clearance but maybe way back when that was the case. All a bit confusing, but if I would guess its the same shell all along since they left the coated OEM. Anyway, some of them comes out in brilliant shape.

Extra Clearance, Undersize, Oversize.... Again, one must look at the numbers, which don't lie. Admittedly, not all of us are engine builders who care to understand all of the details found in bearing spec paperwork. Nomenclature gets lost in translation as the person may be talking about the crankshaft journal or the bearing shell, which will instantly confuse if someone gets it backwards.

Extra clearance: Slight bearing-to-journal clearance is added to the standard (STD) bearing bore diameter, increasing oil clearance from factory spec.

Undersize: Refers to the bearing's reduced final inside bore diameter, used for damaged crankshafts that have been ground "Undersize" from factory dimension. Often erroneously called "oversized" because the bearing shell is thicker.

Oversize: Refers to the bearing's specified outside diameter, used for damaged rod bores or main bearing bores that have been honed larger than factory dimension to clean up damage. (This is not really used in S65 application as only King rod bearings are larger to run in honed rods. There are no oversized main bearings on the market)

[Helmsman]

Originally Posted by deansbimmer

Look at the measurements and reported nominal clearances. Numbers don't lie. VAC Clevite shells yielded .0021" clearance, which is obviously greater than factory clearance, although not as open as BE. The measurements throughout that page are similar to the numbers we get on our Mitutoyo equipment.



Extra Clearance, Undersize, Oversize.... Again, one must look at the numbers, which don't lie. Admittedly, not all of us are engine builders who care to understand all of the details found in bearing spec paperwork. Nomenclature gets lost in translation as the person may be talking about the crankshaft journal or the bearing shell, which will instantly confuse if someone gets it backwards.

Extra clearance: Slight bearing-to-journal clearance is added to the standard (STD) bearing bore diameter, increasing oil clearance from factory spec.

Undersize: Refers to the bearing's reduced final inside bore diameter, used for damaged crankshafts that have been ground "Undersize" from factory dimension.

Oversize: Refers to the bearing's specified outside diameter, used for damaged rod bores or main bearing bores that have been honed larger than factory dimension to clean up damage. (This is not really used in S65 application as only King rod bearings are larger to run in honed rods. There are no oversized main bearings on the market)

Deansbimmer, many thanks for like always taking time to educate. I clearly have missunderstood the concept of under/oversized and mixed with thinner shell (inside) to achieve more clearance. Believe I've got it now...

Keep this up and we'll eventually all be (arm chair) engine builders!

[deansbimmer]

It's definitely confusing. Take ACL for example. Their S65 rod bearings are available in three flavors but they're easily mis-understood.

ACL-H-STD This is the OE standard dimension replacement.

ACL-HX-STD (+0.025 MM) Typically this +.025 would indicate an undersized bearing, if looking at that number only. However, per ACL's description, the X in the prefix identifies this as an "Xtra" clearance spec, making the +.025 signify an additional oil clearance deviation from standard (a thinner bearing shell).

ACL-H+0.25 (+0.250 MM) This is the standard dimension shell for OE journal size (H) +.25mm, making it a thicker bearing shell for re-ground (Undersize) cranks.

So as a result you get all sorts of confusion over undersized/oversized. Looking at their blueprints or dimensional breakdown from BE, is necessary.
The numbers have the final say where terminology breaks down.

[Helmsman]

Originally Posted by deansbimmer

It's definitely confusing. Take ACL for example. Their S65 rod bearings are available in three flavors but they're easily mis-understood.

ACL-H-STD This is the OE standard dimension replacement.

ACL-HX-STD (+0.025 MM) Typically this +.025 would indicate an undersized bearing, if looking at that number only. However, per ACL's description, the X in the prefix identifies this as an "Xtra" clearance spec, making the +.025 signify an additional oil clearance deviation from standard (a thinner bearing shell).

ACL-H+0.25 (+0.250 MM) This is the standard dimension shell for OE journal size (H) +.25mm, making it a thicker bearing shell for re-ground (Undersize) cranks.

So as a result you get all sorts of confusion over undersized/oversized. Looking at their blueprints or dimensional breakdown from BE, is necessary.
The numbers have the final say where terminology breaks down.

Thanks again mate, this is one of the sources that created my confusion.

[Assimilator1]

Yea and ACL have further added to the confusion in their pdf, where it says +0.25mm for the clearance!(inches is correct at 0.001) When they mean 0.025mm, I emailed them yesterday about it.

Originally Posted by deansbimmer

It's definitely confusing. Take ACL for example. Their S65 rod bearings are available in three flavors but they're easily mis-understood.

ACL-H-STD This is the OE standard dimension replacement.

ACL-HX-STD (+0.025 MM) Typically this +.025 would indicate an undersized bearing, if looking at that number only. However, per ACL's description, the X in the prefix identifies this as an "Xtra" clearance spec, making the +.025 signify an additional oil clearance deviation from standard (a thinner bearing shell).

ACL-H+0.25 (+0.250 MM) This is the standard dimension shell for OE journal size (H) +.25mm, making it a thicker bearing shell for re-ground (Undersize) cranks.

So as a result you get all sorts of confusion over undersized/oversized. Looking at their blueprints or dimensional breakdown from BE, is necessary.
The numbers have the final say where terminology breaks down.

One small correction , ACL's H STD has slightly bigger clearances (measured & specs) than the both OEM bearings according to the bearing wiki.
ACL H STD Nominal Rod Bearing Clearance 0.0483 mm 0.00190 inch. Measured was from 0.00190 - 0.00225"
702/703 Nominal Rod Bearing Clearance 0.0381 mm 0.00150 inch. Measured is from 0.00165 - 0.00190"