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      05-16-2016, 10:19 PM   #1
ajee622
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Rod bearing question...

If you decide to do the preventive maintenance and have a shop just replace them, is there an oem substitute that could be purchased so you don't have to worry about this issue??
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      05-16-2016, 10:21 PM   #2
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Quote:
Originally Posted by ajee622 View Post
If you decide to do the preventive maintenance and have a shop just replace them, is there an oem substitute that could be purchased so you don't have to worry about this issue??
I'm pretty sure the oem ones go to shit 50-120k miles

One change should be enough for the rest of your ownership.
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      05-16-2016, 11:01 PM   #3
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I used new BMW bearings, but had them WPC treated. And used new BMW bolts. I did mine at 60k and if I still have the car at 120k, I'll do them again.
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      05-16-2016, 11:02 PM   #4
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Quote:
Originally Posted by opihi5 View Post
I'm pretty sure the oem ones go to shit 50-120k miles

One change should be enough for the rest of your ownership.
I'm pretty sure you are wrong.

Check out bebearings as a substitute for OEM. No guarantees that your problem, if you have one, is eliminated.
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      05-17-2016, 11:08 AM   #5
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Hate to be not helpful, but seriously??

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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      05-17-2016, 03:10 PM   #6
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Question still remains why BMW designed the rod bearings the way they did in the first place...
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      05-17-2016, 03:25 PM   #7
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Question still remains why BMW designed the rod bearings the way they did in the first place...
Highly guarded Bavarian secret. I doubt we will ever know.
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      05-17-2016, 04:03 PM   #8
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Originally Posted by kb9uwu View Post
Highly guarded Bavarian secret. I doubt we will ever know.
I mean these engines must have blown up one after another when they had them on the test bench! The design of the S65 (as I understand) was a downsizing job of the existing S85 design where apparently the rod bearings etc. were of the same faulty design. So why did they also actively ignore blown up S85 engines when they had the chance to rectify it? The later enigne revisions of the S65 did have corrected rod bearings so there must have been a discussion between the bean counters and engine construction sometime between 2007 and 2010... But why not earlier?
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      05-17-2016, 04:06 PM   #9
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Quote:
Originally Posted by one-m3post View Post
I mean these engines must have blown up one after another when they had them on the test bench! The design of the S65 (as I understand) was a downsizing job of the existing S85 design where apparently the rod bearings etc. were of the same faulty design. So why did they also actively ignore blown up S85 engines when they had the chance to rectify it? The later enigne revisions of the S65 did have corrected rod bearings so there must have been a discussion between the bean counters and engine construction sometime between 2007 and 2010... But why not earlier?
I dunno what to tell you, my S65 is almost 9 years old with 95k miles and has yet to blow up.
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      05-17-2016, 04:12 PM   #10
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Quote:
Originally Posted by pbonsalb
I used new BMW bearings, but had them WPC treated. And used new BMW bolts. I did mine at 60k and if I still have the car at 120k, I'll do them again.
Looking forward to seeing what the replacements look like after use
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      05-17-2016, 04:38 PM   #11
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OP, unfortunately there is no guaranteed fix at the moment. No one really knows exactly what the issue is yet. Some bearings have failed at 5000 miles, some guys are well over 100,000 miles without an issue yet.

All you can do is swap them out for peace of mind. None of the aftermarket solutions are quite proven yet.

I went with VAC bearings and ARP Hardware only because a supercharged engine was opened up with 40,000 miles on the bearings and they were clean.



Quote:
Originally Posted by one-m3post View Post
The later enigne revisions of the S65 did have corrected rod bearings
The newer bearings have the same tolerance, they just changed the material. They are not "corrected"
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      05-17-2016, 04:43 PM   #12
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Ok thanks that's all I'm looking for. If the best alternative is oem and oems potential for failure seem to be significant than it is what it is. I just wasn't sure if there was an aftermarket alternative that might be made of something stronger.
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      05-17-2016, 05:23 PM   #13
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I'm no engineer so this may be a silly question, but if the crankshaft diameter/rod journals are a certain diameter and the clearance is small on our stock bearings, why couldn't they just engineer a very slightly thinner rod bearing to increase clearance? Will that resulting bearing be too thin to be useful in operation and fail anyway?
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      05-17-2016, 06:04 PM   #14
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Quote:
Originally Posted by Edward
I'm no engineer so this may be a silly question, but if the crankshaft diameter/rod journals are a certain diameter and the clearance is small on our stock bearings, why couldn't they just engineer a very slightly thinner rod bearing to increase clearance? Will that resulting bearing be too thin to be useful in operation and fail anyway?
BE Bearing, which is a custom Clevite bearing. It had a small run prompted by a couple by some former members. I think they're doing another production run in the next couple months. There are long discussions about bearings and rod bolts on this and probably other forums. Non stock bolts will deform the big end housing bore. It's all noted in a thread about bearings. Most people who do this type of replacement have no clue about an internal combustion engine, I get very uneasy with not being able to measure housing bores. Too tight everyone knows, too loose no one knows. .001" clearance per inch of shaft diameter is a rule of thumb.
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      05-18-2016, 01:31 AM   #15
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VAC coated Rod Bearings. WITH ARP VOLT IS THE WAY TO GO
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