Official S65 Bearing Specification/Clearance Wiki

[Longboarder]

Thanks for all the hard work. You certainly aren't a "regular guy" after all. I need to re- read your posts a couple more times to get it to sink in.

[thekurgan]

Interesting the WPC bearings are only using the latest BMW rod bearings as a start. I wonder what that Babbitt material is made from.

Again, nice work.

[Billj747]

Thank you for your hard work and proper objective scientific testing. You're a huge benefit to the community.

While Im not claiming that it directly addresses the main S65s issues, I have had a lot of success with WPC treated bearings, pistons, rings, gears, etc... in various racing applications.


On another note:

What is FCT+VAC and CARR+VAC?

how did you measure 0.00290 clearance when you inferred from the thicker bearing a 0.0009-0.0016 clearances?

[Trip3's]

Thanks Regularguy for all your research. I have to do an oil change soon and was searching threads to make sure it was M1 0W40 that I wanted and I realized that we have the Holy Trinity amongst us: Regularguy, Kawasaki00, and Bmrlvr. Who contribute and educate the community with REAL DATA and not opinions. It is much appreciated!

[lsmkr01]

Originally Posted by Billj747

On another note:

What is FCT+VAC and CARR+VAC?

Factory Rod + VAC (coated) bearing and Carrillo Rod + VAC (coated) bearing.

Glad to have you on the forum Billy.

[kawasaki00]

Originally Posted by Trip3's

Thanks Regularguy for all your research. I have to do an oil change soon and was searching threads to make sure it was M1 0W40 that I wanted and I realized that we have the Holy Trinity amongst us: Regularguy, Kawasaki00, and Bmrlvr. Who contribute and educate the community with REAL DATA and not opinions. It is much appreciated!

Thanks dude, nice to have a few guys that really want to make a difference instead of just posting nonsence
regularguy has helped a bunch with having these parts in front of him to see the differences with all the processes

[nineonenine]

So does this sh*t mean I should dump my Jan 2009 build M3 that is out of warranty? Has 30k miles on it. wtf?

[Wendall]

great work regular guy! I really appreciate it. Will Autotalent be selling these WPC rod bearing kits in the future?

[Trip3's]

Originally Posted by nineonenine

So does this sh*t mean I should dump my Jan 2009 build M3 that is out of warranty? Has 30k miles on it. wtf?

I would dump it immediately, I will take it off your hands for $25k. This offer expires in 24 hours. On a serious note, I would read through some of the threads on this topic and decide for yourself OR wait for Regular guy to add more info to this thread before you make a decision. Opinions vary, but most people aren't thinking about checking for a problem before 50k from what I have read.

[kawasaki00]

Originally Posted by Trip3's

I would dump it immediately, I will take it off your hands for $25k. This offer expires in 24 hours. On a serious note, I would read through some of the threads on this topic and decide for yourself OR wait for Regular guy to add more info to this thread before you make a decision. Opinions vary, but most people aren't thinking about checking for a problem before 50k from what I have read.

Most are waiting till 60-75k miles around here. Usually if it makes it past 25 then it is good for a while.

[gatorfast]

Granted there is some evidence of bearing wear from engines that have been examined recently. But how many actual documented failures are there? How much wear can be sustained until the engine fails?

[nineonenine]

Damn I was hoping to tell the wife I needed to get a GTR before my engine explodes and causes us to go bankrupt. (the bankruptcy thing is a joke, no need to tell me I cant afford a GTR :-P )

[JS11]

Originally Posted by biggynuts01

great work regular guy! I really appreciate it. Will Autotalent be selling these WPC rod bearing kits in the future?

you can get your stuff wpc treated yourself. they're close to you in torrance and i heard the turnaround is pretty quick.

[regular guy]

Originally Posted by thekurgan

Interesting the WPC bearings are only using the latest BMW rod bearings as a start.

WPC will treat whatever you send them. If you send them old bearings, they will treat old bearings. Auto Talent sent them new bearings, hence the treatment on new bearings.

Originally Posted by Billj747

On another note:

What is FCT+VAC and CARR+VAC?

how did you measure 0.00290 clearance when you inferred from the thicker bearing a 0.0009-0.0016 clearances?

As another member mentioned, FCT+VAC == Factory ROD + VAC bearing, and CARR + VAC == Carrillo ROD + VAC bearing.

I'm sorry I muddled the explanation of the 0.00290 clearance. That was measured, not calculated from a single journal I measured inside the engine of the EAS car. Then we pulled one rod out of my collection, installed a bearing, torqued it and measured. There's two things we did wrong here: 1) We didn't remove the Calico coating from the parting lines which will affect the measurements; 2) I don't know which rod was used -- as I just grabbed one from the box. I didn't yet know that the rod bores differed so much in size. Had I known this at the time, I would have grabbed Rod #4. I thought I had a duty to mention this test because I didn't want to cover it up, but I'm sorry it was inconclusive as we didn't really do it right or scientifically.

I have a friend sending me a set of VAC bearings soon. I will put them in the same connecting rods and measure it before posting the results.

Originally Posted by biggynuts01

great work regular guy! I really appreciate it. Will Autotalent be selling these WPC rod bearing kits in the future?

I believe so, but best to call them to check. I have a hunch a few vendors will now be looking at the WPC process as well.

Originally Posted by gatorfast

Granted there is some evidence of bearing wear from engines that have been examined recently. But how many actual documented failures are there? How much wear can be sustained until the engine fails?

Wait until I get the bearing photo database in place. You will get a chance to see all the ones I could find posted, along with a few you haven't. Some engine failures aren't reported on the forums, but do get mentioned in private emails amongst friends. A few months ago, there was a failure of a mostly stock M3. The rod snapped in half, and the big end of the rod was blue with heat damage. Those are clear signs of excessive heat due to lack of lubrication. There's others as well, but no permission yet to post the photos or details.

[signes]

Excellent data and analysis, looking forward to the rest of the story to come.

[jcolley]

I can't say thank you enough for this. Lilke most newly discovered / newly popular issues with our cars, it gets a lot of attention from both the naysayers an the chicken littles. It's a natural human reaction, but with time and a little concise evidence and information, it will become just another one of those things we deal with as part of ownership.

I've been emailing Sam at AutoTalent and he confirmed about $4/bearing and I suggested he may want to stock up...

Originally Posted by regular guy

Wait until I get the bearing photo database in place. You will get a chance to see all the ones I could find posted, along with a few you haven't. Some engine failures aren't reported on the forums, but do get mentioned in private emails amongst friends. A few months ago, there was a failure of a mostly stock M3. The rod snapped in half, and the big end of the rod was blue with heat damage. Those are clear signs of excessive heat due to lack of lubrication. There's others as well, but no permission yet to post the photos or details.

Here is a thread on M5Board doing just that. It was intended initially to only have pictures of bearings out of functional engines, but some others have been posted and serve as a warning of the extreme end.

http://http://www.m5board.com/vbulle...re-thread.html

[jbraslins]

Thank you!

[cambit]

thanks for this in-depth writeup. As a layman / Non-mechanic I understand none of this. Just tell me how much and who do I write the check to? MY2013 E92, July 2012 build.

[regular guy]

Mahle-Clevite White Paper on Bearing Clearance Issues

This quote comes directly from a Mahle-Clevite white paper on bearing clearance, then I'll summarize at the end.

For most applications .00075 to .0010” (three quarters to one thousandth of an inch) of clearance per inch of shaft diameter is a reasonable starting point.

...

Using this formula will provide a safe starting point for most applications. For High Performance engines it is recommended that .0005” be added to the maximum value determined by the above calculation. The recommendation for our 2.000” shaft would be .0025” of clearance.

...

High Performance engines on the other hand, typically employ greater bearing clearances for a number of reasons. Their higher operating speeds result in considerably higher oil temperatures and an accompanying loss in oil viscosity due to fluid film friction that increases with shaft speed. Increased clearance provides less sensitivity to shaft, block, and connecting rod deflections and the resulting misalignments that result from the higher levels of loading in these engines. Use of synthetic oils with their better flow properties
can help to reduce fluid film friction.

...

Use of these coated bearings may result in slightly less clearance than the uncoated CLEVITE 77® high performance parts for the same application. This will typically be in the range of .0005.” This is because the coating, although expected to remain in place during service, is considered to be somewhat of a sacrificial layer. Some amount of the coating will be removed during break-in and operation, resulting in a slight increase in clearance.

Here's what this means to you. If you run high horsepower and high RPM, then you need extra bearing clearance, not less of it. The coated bearings are great, but you have to size your journals for them; and as Alekshop mentioned in a previous thread, you shouldn't have coated parting lines. If you have coated parting lines you must remove the coating in this area before using these bearings.

Mahle-Clevite recommends adding an extra 0.0005 for good measure for high horsepower, high RPM, and coated bearing applications. To see some numbers in real life, please see the following examples.

Factory clearance: 0.00125
Factory clearance with Calico coated bearings: 0.00085 - 0.00105 (16-32% smaller).
Factory clearance with TriArmor coated bearigns: 0.00075 - 0.00095 (24-40% smaller).

Recommended clearance for mains (70mm journal):
0.00100/inch + 0.0005 = 0.00325
0.00075/inch + 0.0005 = 0.00256

Recommended clearance for rods (52mm journal):
0.00100/inch + 0.0005 = 0.00205
0.00075/inch + 0.0005 = 0.00153

So there you have it: ideal mains should be 0.0025 - 0.0032 and ideal rods should be 0.00153 - 0.00205. You're given 0.00125 clearance from the factory and some may be thinking of reducing it another 16-40% with coated bearings without sizing the journals because they believe it gives them extra protection. The extra protection is true if you kept all things the same including the bearing clearance; but reducing the bearing clearance by 16-40% to get the extra protection of the coating is not recommended.

Some Photo Evidence of Oil Starvation

Time to add some pictures to the discussion to see what a bearing looks like due to lack of clearance. The first few pictures come straight from Mahle-Clevite. Thanks to BMRLVR for posting the B&W version of the Clevite bearing failure guide. I found the color version of the same thing. It looks like the color version has better pictures, but the B&W version might have some better illustrations and explanations. So here's both versions for reference.

B&W: hhttp://www.wilmink.nl/Clevite/Clevite_lagerschade_tech_info.pdf
Color: http://catalog.mahleclevite.com/bearing

Using the color bearing failure guide, see example #12 "Oil Starvation / Marginal Oil Film Thickness." The two pictures below come from this example. According to Mahle-Clevite, the number-one cause of failure of this type is too little oil clearance.





Next, let's compare these reference photos to some actual S65 bearings from various engines. Where possible, the mileage and circumstances will be mentioned. These photos are all found in other threads on this forum.


Engine-1: Modifications unknown, stock internals, Mileage: 24,000.




Engine-2: Bone Stock, stock internals. Mileage: ~20,000

This bone stock engine suffered from main bearing failure. Notice the wear spot on the main bearing and the appearance of a channel the oil made to get around it. The connecting rod bearings aren't much better. Many of the connecting rod bearings show signs of excessive wear due to oil starvation (too little clearance).













Engine-3: Upgraded internals, supercharged, Mileage: 24,000






Engine-4: Stock internals, supercharged, Mileage: 72,000




Engine-5: Stock internals, supercharged, Mileage: 90,000



The connection between these pictures and the reference Mahle-Clevite pictures is obvious. Even though there can always be multiple causes of oil starvation and bearing failure, the number one cause of the damage shown in these pictures is listed by Mahle-Clevite as too little bearing clearance.

I have more photos that I will post in the Bearing Photo Database. I've got at least one set, maybe two sets of photos of broken (snapped) S65 connecting rods with the big end of the connecting rod turned blue due to excessive heat (oil starvation due possible bearing clearance).

I hope these photos have been helpful to see with your own eyes what this problem looks like, and why it's happening.

[kawasaki00]

[Malek@MRF]

Thread of the year!!

[apecush]

By chance, has anybody done any research into the "why" of the tight clearances? As we know, bearing clearance and oil pressure are very closely related. Any plans to research whether the stock oil pump can in fact maintain the required flowrate when the clearances get opened up? I can see this short term "fix" going south in a hurry if all factors aren't considered. I'm not criticizing the work, obviously this is a huge benefit to the community, I'm just suggesting that some attention be paid to the big picture.