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Out of everything I've seen about rod bearings you're the first to claim bearing wear is due to excessive clearance. Not even Troy would agree with that (he certainly doesn't follow bmw specs). You post a great link about ideal clearance and then state exactly the opposite here. Yes too loose is bad (think ACL HX), but so is too tight (i.e. BMW). The pic above does not consider the too tight scenario.

I've stated long ago that tighter clearance helps increase bearing load capability. Comes straight from journal bearing load formulas. But obviously there's a limit where other issues (heat, lubrication) come into play.

There's no point mentioning Jim and BE's experiments showing thinner oil being useless in reducing bearing wear because... people simply believe what they want to believe.
 

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Just providing food for thought.

My statement is simply an observation of actual bearing wear (see picture) as compared to well established rules (per Article cited) for using previous wear pattern to set up new “Static” bearing clearance.

The big misconception on m5board is that the initial static bearing clearance exists in the actual “Dynamic” environment at 8,000 rpm due to bearing housing distortion”

As stated in link below:

“However the real situation is more complicated than the theoretical calculations. As a matter of fact, the actual eccentricity of high performance bearings during their operation is lower than the difference between the maximum and minimum wall thickness. The eccentricity is reduced by distortions of the bearing housing due to high loads and high rotation speeds. Using King’s ENSIM™ software we are able to determine the optimal eccentricity value for a specific performance requirement. This optimal value in our XP and HP race series is called EccentriX™“

Optimization of clearance design for high performance engine ...
 

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The very real issue is when one looses eccentricity (due to load distortion) one looses the ability to form a hydrodynamic wedge to carry loads to avoid metal to metal contact.

Perhaps this is why King offers their silver clad GPC bearing for the s85 in their E catalogue which is just below their Top Fuel bearing in load capability
8B5A2EF1-2B9D-42F5-8C8F-949B60A320F1.jpeg
AA6F9669-9E38-47DF-8285-EA144FDE092A.jpeg
B4CAE011-951D-4351-B97B-47F8CE7318EB.jpeg
C5F97FED-6FB4-447B-A4DB-16C8746AC8D7.jpeg
that holds up to 10,000 HP
 

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There's no point mentioning Jim and BE's experiments showing thinner oil being useless in reducing bearing wear because... people simply believe what they want to believe.
I agree with this.
I'm interested in thinner oil - on the "W" side - because of time to moving parts throughout the engine at lower temperatures. (Canada, eh!). IIRC, the 10W60 weight is proposed because of how at temperature, the "60" becomes more like a "50". However, for the time being I am running 10W60 (Liqui-Moly) and stashing the M5 in the winter (Oct - May).
 

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Hi All,

I dont come or post here much but now that my 2008 E50 M5 has just turned 90K miles, I wanted to check the boards for any potential issues. I'm pretty good on maintenance intervals but this rod bearing issue has me a little concerned. I talked to my trusted mechanic (former BMW mechanic who now owns an indy shop) about any preventative maintenance that i need to do...rod bearing, VANOS high pressure hose, VANOS solenoids, oil pump, etc. He said that since i have an 08, i shouldn't see these same issues but the SMG is and will always be a concern. He himself has an 08 and hasnt done any of these items.

is he correct? is these issues with pre-LCI models only? is my build date relevant? i dont have it off-hand but i can run to the garage if it makes a difference.

thoughts?
 

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Hi All,

I dont come or post here much but now that my 2008 E50 M5 has just turned 90K miles, I wanted to check the boards for any potential issues. I'm pretty good on maintenance intervals but this rod bearing issue has me a little concerned. I talked to my trusted mechanic (former BMW mechanic who now owns an indy shop) about any preventative maintenance that i need to do...rod bearing, VANOS high pressure hose, VANOS solenoids, oil pump, etc. He said that since i have an 08, i shouldn't see these same issues but the SMG is and will always be a concern. He himself has an 08 and hasnt done any of these items.

is he correct? is these issues with pre-LCI models only? is my build date relevant? i dont have it off-hand but i can run to the garage if it makes a difference.

thoughts?
If you read through all 56 pages of this thread, you will get the answer you're looking for. Do the rod bearings. I bought an 08 M5 also, and the PO had the motor replaced under warranty at 68k due to rod bearing failure. This motor has 70k on it, and you better believe I changed the bearings. They weren't about to fail, but they were worn down to the copper. Pics posted on page 53.. There's countless examples of the 08+ S85 having the same issue. Just do it.
 

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If you read through all 56 pages of this thread, you will get the answer you're looking for. Do the rod bearings. I bought an 08 M5 also, and the PO had the motor replaced under warranty at 68k due to rod bearing failure. This motor has 70k on it, and you better believe I changed the bearings. They weren't about to fail, but they were worn down to the copper. Pics posted on page 53.. There's countless examples of the 08+ S85 having the same issue. Just do it.
Agreed, I have a very late built 2010 (down to the last 400 made) and you better believe I did mine at 63k miles. Not much wear but I did have a PO who babied the car. Just do it. Spend $2500 to save $10,000.


2010 E60 M5 • Space Grey
 

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Here is mine on 61k 2008 m6. The worst been on cyl 10. Some of them even didn’t show the copper at all. Swapped with ACL hx. Pumpes are looking great
 

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If you read through all 56 pages of this thread, you will get the answer you're looking for. Do the rod bearings. I bought an 08 M5 also, and the PO had the motor replaced under warranty at 68k due to rod bearing failure. This motor has 70k on it, and you better believe I changed the bearings. They weren't about to fail, but they were worn down to the copper. Pics posted on page 53.. There's countless examples of the 08+ S85 having the same issue. Just do it.
Agreed, I have a very late built 2010 (down to the last 400 made) and you better believe I did mine at 63k miles. Not much wear but I did have a PO who babied the car. Just do it. Spend $2500 to save $10,000.


2010 E60 M5 • Space Grey
thanks for your input. very valuable.
 

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If you read through all 56 pages of this thread, you will get the answer you're looking for. Do the rod bearings. I bought an 08 M5 also, and the PO had the motor replaced under warranty at 68k due to rod bearing failure. This motor has 70k on it, and you better believe I changed the bearings. They weren't about to fail, but they were worn down to the copper. Pics posted on page 53.. There's countless examples of the 08+ S85 having the same issue. Just do it.
Yup, he's right. There's a lot of good info and like most other concerned owners, I've read all the pages myself as well. You can find my post some where on here too. Mine is also an 08.

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