BimmerRob08 wrote So over time I've read through the 100+ pages of posts and talked to my BMW tech (not dealership, private performance BMW shop) and I'm still not sure which bearings to go with. My M3 is a 2008 early model with copper bearings. I'm the original owner. Oil samples come back very promising but at 98,000 miles, I think it's time to get the bearings done. With that, my tech said to stick with OEM bearings, and they've done a good deal of them over the years.
I've read here that some of the larger clearance aftermarket bearings seem to perform fine, so it seems so far. So, what do I go with? I plan on keeping my M3, so I'd like to not have to have a bad surprise 50K miles down the road or need to re-due them for preventative maintenance someday down the road. Probably something I can't avoid on this engine but if aftermarket might allow more duration, that would be good. What do you all suggest with experience with the aftermarket bearing kits?
Cheers,
RB
Not many here will break with the "consensus" that OE rod bearings suck. For the longest time, everyone blindly accepted that narrative and anyone who questioned it got mobbed (sometimes understandably; some of the questioners behaved very badly).
Thankfully, that's starting to change now. Long past time in my opinion, but better late than never. Some points in the "OE rod bearings suck" narrative have been cast into serious doubt; a few have been outright debunked. At this point so many people have done BE and other aftermarket bearings that the confirmation bias will be hard to overcome. But at least the shout-downs and condescension are less common.
I went with new OE bearings 74k miles ago and I lose exactly zero sleep over them. My thinking back then was that I hadn't seen hard evidence showing that engines with other bearings lasted any longer than ones with the updated OE bearings. That's still true, as far as I can tell. People have posted some good-looking pics of used BE bearings, but that means nothing to me. What I care about are engine failure rates, and no one's gathering those stats in a way I'm comfortable with. In fact, every time an engine fails with aftermarket rod bearings, people blow it off as "the main bearings failed first" and assume it has nothing to do with the rod bearings. That scares me TBH. What we should do is count all failures with all bearing types and let the overall numbers speak.
We've also seen evidence that the updated OE bearings don't seem to wear
nearly as much as people had assumed. What a lot of us had assumed was critical wear actually seems to be superficial discoloration of the top layer. I have yet to see a single updated OE rod bearing that has definitely worn down to the actual copper layer in anything like normal use. And, barring a few early failures, engines with these bearings seem to be holding up just fine after tons of street miles and track use. I had originally planned on replacing my rod bearings again after 60k-80k miles; now, I suspect I won't touch them for the rest of the time I own the car.
Happy to go into this more over PM if you want.
)) But I have BE + ARP.
)
