[lforter]

Hello, I want to remplace my rod bearings, wanted know what's good and what to stay away from, was considering King but I have seen some fail (vehicular DIY), was looking for ACL but there out of stock everywhere. Now there other brand, Kolbenshmidt how good are they?

[Ozzie335i]

Originally Posted by lforter

Hello, I want to remplace my rod bearings, wanted know what's good and what to stay away from, was considering King but I have seen some fail (vehicular DIY), was looking for ACL but there out of stock everywhere. Now there other brand, Kolbenshmidt how good are they?

It comes down to one thing. One test is worth 1000 opinions. Unfortunately with the internet one opinion on a site that is well viewed can skew others' good results. While vehicular DIY had bad luck with the King bearings, I don't recall anybody having bad luck with them, fatty and myself among them.

I went with them for the additional clearance, as do many hot rodders. My logic is if there is a momentary loss of pressure there is a tad more lubrication in there to hopefully buy time until pressure is restored. Right or wrong I beat on my Pure 2 port injected N55 every time I drive it. Obviously after a proper warm up. Whatever your choice, please let us know how the install went, and do plastigage every bearing during installation.

[wheela]

Plus 1 on what ozzie said.

Is there a reason you don't just replace them with oem rod bearings?

[wheela]

I'll probably do them preventatively with oem bearings around 100k just for peice mind. Or whenever my oil pan starts leaking. With x-drive, getting in there will be a pain, so the way I see it may as well swap the while it's opened up.

I'm not diligent about letting it fully warm up before going WOT, so I'll definatly post how they look when the time comes. Knock on wood, hopefully I don't regret my relative disregard for proper warm up, and it will be a preventative replacement (as planned) when the time comes.

[whyzee125]

King, ACL, OEM, Kolbenschmidt will all be just fine. It's usually recommended to use OEM bolts I believe.

Kolbenschmidt used to be an OE manufacturer for e30s and some other models.

I have coated King bearings because it's what the shop who did mine recommended. I've had no issues.

Vehicular DIY is the only person I've ever heard of having issues but I don't think his King bearings were defective. There are a few other more plausible explanations.

1) 220k mile engine had worn main bearings and the mismatch caused it
2) there was more timing chain guide material that was not cleaned out of the engine
3) he admittedly didn't let it warm up, so while doing this once shouldn't spin a bearing, it definitely could contribute if something wasn't quite right already
4) possible contamination while doing the job

[bmw335ie90]

Originally Posted by wheela

I'll probably do them preventatively with oem bearings around 100k just for peice mind. Or whenever my oil pan starts leaking. With x-drive, getting in there will be a pain, so the way I see it may as well swap the while it's opened up.

I'm not diligent about letting it fully warm up before going WOT, so I'll definatly post how they look when the time comes. Knock on wood, hopefully I don't regret my relative disregard for proper warm up, and it will be a preventative replacement (as planned) when the time comes.

Why would you not let your oil fully warm before going WOT, especially on an engine with known rod bearing issues? Not really understanding that at all.

[wheela]

Originally Posted by bmw335ie90

Why would you not let your oil fully warm before going WOT, especially on an engine with known rod bearing issues? Not really understanding that at all.

Well, maybe they're not good reasons, but there are a few reasons why I do. Please keep in mind this is my own conjecture based off of my unique experience and thoughts, no testing to back any of it up, and certainly NOT a recommendation for anybody to not let their motor warm up before beating on it!!!

-from my readings, the rod bearing issue anecdotally seems related to oil starvation. In particular, long, high-g, left hand turns combined with the angle of the block starving the oil pickup. This scenario isn't happening on my commute.

-short commute. No point in daily driving a fast car if I can't get on it.

-Yes, oil viscosity changes with temperature. But in a previous job, I supported production of high viscosity solutions, and have done a lot of viscosity testing. Barring really cold temperatures (sub freezing), the difference in viscosty numbers you see at say 60F and at operating temp of 240F looks very significant. But in reality, I think the practical difference in terms of flowability and lubricity between those viscosities probably aren't that significant.

-colder, high viscosity oil doesn't flow as fast through the pump at a given pressure as it does when warmer, but that colder oil is also going to resist getting pushed out of the bearing gap more than when it's warm. So you probably don't need as much flow for the same protection when it's cold.

-BMW doesn't say let it warm up before beating on it. (But they also say not to replace your transmission fluid so probably not with putting stock in).

Again, no evidence for ANY of this, and NOT a recommendation to beat on a cold engine. Just the reasons I don't loose sleep over it. Hopefully I won't regret it.

[bbnks2]

Originally Posted by Ozzie335i

It comes down to one thing. One test is worth 1000 opinions. Unfortunately with the internet one opinion on a site that is well viewed can skew others' good results. While vehicular DIY had bad luck with the King bearings, I don't recall anybody having bad luck with them, fatty and myself among them.

I went with them for the additional clearance, as do many hot rodders. My logic is if there is a momentary loss of pressure there is a tad more lubrication in there to hopefully buy time until pressure is restored. Right or wrong I beat on my Pure 2 port injected N55 every time I drive it. Obviously after a proper warm up. Whatever your choice, please let us know how the install went, and do plastigage every bearing during installation.

King bearings don't have "extra clearance" unless they are the "x" bearings.

Vdiy didn't really have any issue with king bearings. He put in aftermarket bearings and they spun a few months later... because spun bearings generally has very little to do with the bearing itself failing. Could've been poor stack buildup in the tolerance reducing crush or messing with some other key clearance but im confident whatever caused his spun bearings a few thousand miles after installing the KING would've happened no matter what brand he was running. Maybe he didn't torque rod bolts right. Maybe the rod caps were stretched. Maybe his car had a mechanical issue like misfires. who knows.

[IllSic_Design]

at least 20k miles on my coated kings with no issues. I've been hard and beat on it a few times before it was over 160* also

[lforter]

Will order calico coated king rod bearings, been looking for ACL for too long. Will report my findings

[ferocity02]

Does replacing the rod bearings reduce any tapping sounds that you might have had, but weren't identified as a failed rod bearing?

[Ozzie335i]

"King bearings don't have "extra clearance" unless they are the "x" bearings."

While I didn't specifically order X bearings, extra clearance is what I wanted and ended up with. Maybe they sent the X one anyhow.

As far as the diy guy, he had installed the King bearings, and made it a point to say so.

[bbnks2]

Originally Posted by Ozzie335i

"King bearings don't have "extra clearance" unless they are the "x" bearings."

While I didn't specifically order X bearings, extra clearance is what I wanted and ended up with. Maybe they sent the X one anyhow.

As far as the diy guy, he had installed the King bearings, and made it a point to say so.

you ended up with ~.0025-.0027" clearance with king?

[Ozzie335i]

Originally Posted by bbnks2

you ended up with ~.0025-.0027" clearance with king?

I don't recall the exact numbers as it's been 3 years. But I discussed it with the sales guy, and my mechanic confirmed a slight increase in clearance with the spaghetti. As I am an old codger no longer making 6 figures, this is my end of life street rod, and hope my choices were right. Maintenance mode, and crossing fingers on bearing health is an OK place to be.

[lforter]

Just wanted to update, I went with King Calico Rod Bearings. I have been trouble free for the last 7k miles. Some autocross days here and there (haven´t logged G forces). If I were to choose again, I would have probably opted for ACL calico coated rod bearings just because the car is going to take some beating on track and some extra insurance is always good, otherwise the King bearings seem to do the job and it might be just enough.

[yupetc]

I went with King's sputter bearings, part#: CR222GPC

This set is as close as you can get to mimic the B58 rod bearings. B58 rod bearings has the "irox" orange coating on the thrust side. The King's sputter bearings have similar coat, and it's on both sides. I've used this for 20k miles in a full year so far, beat on it when I get the chance and just took it out last month for an inspection. It looks like there's not a scratch on the coating still. Amazing stuff. Get this one, guys, you won't regret it.

Note: Make sure you know what bearing clearance you end up with. On bearing gap less than two-thou (not recommended on aftermarket and modified setup), you can use 20 viscosity oil, between 2-3-thou, you can use 30 vis oil. You shouldn't let your clearance go beyond 3.5-thou unless you're doing extreme drag race with it, and beyond 3-thou, you should use 40-vis oil. Just my very own recommendations.

OEM bearings are dialed in at 0.00135-0.00150" range when new. That's very tight and easy to overheat in absence of oil film. That's also why we easily catch spun rod bearing issues. Oil starvation is the main cause, but it's also that tight clearance that helped speed the failure up when the oil film is absent.

[lforter]

Originally Posted by yupetc

I went with King's sputter bearings, part#: CR222GPC

This set is as close as you can get to mimic the B58 rod bearings. B58 rod bearings has the "irox" orange coating on the thrust side. The King's sputter bearings have similar coat, and it's on both sides. I've used this for 20k miles in a full year so far, beat on it when I get the chance and just took it out last month for an inspection. It looks like there's not a scratch on the coating still. Amazing stuff. Get this one, guys, you won't regret it.

Note: Make sure you know what bearing clearance you end up with. On bearing gap less than two-thou (not recommended on aftermarket and modified setup), you can use 20 viscosity oil, between 2-3-thou, you can use 30 vis oil. You shouldn't let your clearance go beyond 3.5-thou unless you're doing extreme drag race with it, and beyond 3-thou, you should use 40-vis oil. Just my very own recommendations.

OEM bearings are dialed in at 0.00135-0.00150" range when new. That's very tight and easy to overheat in absence of oil film. That's also why we easily catch spun rod bearing issues. Oil starvation is the main cause, but it's also that tight clearance that helped speed the failure up when the oil film is absent.

Just one note, the one you installed are trimetal bearings, these are softer bearings. I used the standard king ones which are bimetal (harder) and then were coated by calico.

[yupetc]

Originally Posted by lforter

Just one note, the one you installed are trimetal bearings, these are softer bearings. I used the standard king ones which are bimetal (harder) and then were coated by calico.

Yes, you're correct. The bimetal bearings have been mainstream for general purpose engine use and has very excellent wear resistance than the trimetal bearings in a low horsepower use scenario.

The bimetal bearings usually have a steel backing with some aluminum/silicon composite as the second layer. This aluminum/silicon layer is very hard, so hard so that as long as the oil film stays in tact, you can carry this set of bearings to 170k miles without worrying about bearing wear. Of course there are other factors to vary the wear rate, but in general, that's how a bimetal bearing works. It's built for longer use, under very light loads to where the oil film stays filled in the bearing clearance. But on an occasions of oil starvation, or if you're running high horsepower with bimetal bearings, the crank drives a stronger thrust and packs a heavier punch towards the bearing. At times, the power is so hard that the oil film gets thinner and thinner until there aren't enough effective oil film layer left, you'll get metal to metal contact. As metal to metal contact, heat will be generated, and that's how you get that bearing shell to weld onto the crank journal. I must say, BMW's OEM bearing clearance at 0.00135 certainly yields a very low level of oil film for this tribology of nearly contacting parts. That OEM rod clearance spec certainly doesn't help with heat control under high loads.

In a situation where you're building your engine to run so high a horsepower, a trimetal bearing is preferred to add a sacrificial layer, buy time before total failure, and allow better heat dissipation. Usually they use the same steel substrate as the base layer, copper as the soft and smooth second layer, then on the third layer you get this babbit with a fluidy tin-foil-like construct and if the high horsepower load has beat the oil out and make contact between crank and the bearing, you will not get as much heat and the babbit is allowed to deform enough before welding in will occur. In terms of making this thing last, I don't think this can do much better than bimetal bearings. But if you're playing your car above 500whp, yeah, trimetal bearings wouldn't be a bad safekeeping mod to do. My build will probably just max out at 400whp on my stock turbo. But one of those days when I upgrade the turbo and fueling, I won't have to worry about my rod bearings.

Trimetal bearings are now becoming more mainstream to use on the trust side of the rod because of automatic start/stop functions that are added to the later cars. It's the manufacturer's belief that frequent auto start/stop function puts a load on the thrust side when the car needs to wake up from a stop because the oil film will possibly settle down and get too thin during the wait. This is why when you open up a B58 rod, you'll see their thrust side bearing shell is shiny orange, it's BMW's supposed proprietary "iRox" coating. The CR222GPC is very close to that.

[lforter]

Originally Posted by yupetc

Yes, you're correct. The bimetal bearings have been mainstream for general purpose engine use and has very excellent wear resistance than the trimetal bearings in a low horsepower use scenario.

The bimetal bearings usually have a steel backing with some aluminum/silicon composite as the second layer. This aluminum/silicon layer is very hard, so hard so that as long as the oil film stays in tact, you can carry this set of bearings to 170k miles without worrying about bearing wear. Of course there are other factors to vary the wear rate, but in general, that's how a bimetal bearing works. It's built for longer use, under very light loads to where the oil film stays filled in the bearing clearance. But on an occasions of oil starvation, or if you're running high horsepower with bimetal bearings, the crank drives a stronger thrust and packs a heavier punch towards the bearing. At times, the power is so hard that the oil film gets thinner and thinner until there aren't enough effective oil film layer left, you'll get metal to metal contact. As metal to metal contact, heat will be generated, and that's how you get that bearing shell to weld onto the crank journal. I must say, BMW's OEM bearing clearance at 0.00135 certainly yields a very low level of oil film for this tribology of nearly contacting parts. That OEM rod clearance spec certainly doesn't help with heat control under high loads.

In a situation where you're building your engine to run so high a horsepower, a trimetal bearing is preferred to add a sacrificial layer, buy time before total failure, and allow better heat dissipation. Usually they use the same steel substrate as the base layer, copper as the soft and smooth second layer, then on the third layer you get this babbit with a fluidy tin-foil-like construct and if the high horsepower load has beat the oil out and make contact between crank and the bearing, you will not get as much heat and the babbit is allowed to deform enough before welding in will occur. In terms of making this thing last, I don't think this can do much better than bimetal bearings. But if you're playing your car above 500whp, yeah, trimetal bearings wouldn't be a bad safekeeping mod to do. My build will probably just max out at 400whp on my stock turbo. But one of those days when I upgrade the turbo and fueling, I won't have to worry about my rod bearings.

Trimetal bearings are now becoming more mainstream to use on the trust side of the rod because of automatic start/stop functions that are added to the later cars. It's the manufacturer's belief that frequent auto start/stop function puts a load on the thrust side when the car needs to wake up from a stop because the oil film will possibly settle down and get too thin during the wait. This is why when you open up a B58 rod, you'll see their thrust side bearing shell is shiny orange, it's BMW's supposed proprietary "iRox" coating. The CR222GPC is very close to that.

I don´t think metal on metal contact occurs on our cars because of the high horsepower. There are several high-horsepower n54 around with no problems to bearings, I dont know how neccesary are trimetal softness since our cars dont rev that high, however, in our case (n54 and n55) the babbit could help as an extra layer of protection, as long as it keeps it, it provides less chance of seizing, otherwise they will seize faster than a bimetal (theres a PDF from king where they show this on some test).

I believe the problem with our cars is oil starvation and contamination during high Gs and poor maintenance. So if you replace the rod bearings I would suggest going for some coating or WPC treatment or not do them (since if you just change them for normal bearings you are just as likely to failure, since the problem is not the bearing itself). Going for bi metal or tri metal is a personal choice, but I dont think it will matter much, maybe if you drag race it will be better for tri metal? or if you dissassemble your engine often. In any case, the main problem will persist (oil starvation) so other solutions must be proposed.

[yupetc]

Originally Posted by lforter

I don´t think metal on metal contact occurs on our cars because of the high horsepower. There are several high-horsepower n54 around with no problems to bearings, I dont know how neccesary are trimetal softness since our cars dont rev that high, however, in our case (n54 and n55) the babbit could help as an extra layer of protection, as long as it keeps it, it provides less chance of seizing, otherwise they will seize faster than a bimetal (theres a PDF from king where they show this on some test).

I believe the problem with our cars is oil starvation and contamination during high Gs and poor maintenance. So if you replace the rod bearings I would suggest going for some coating or WPC treatment or not do them (since if you just change them for normal bearings you are just as likely to failure, since the problem is not the bearing itself). Going for bi metal or tri metal is a personal choice, but I dont think it will matter much, maybe if you drag race it will be better for tri metal? or if you dissassemble your engine often. In any case, the main problem will persist (oil starvation) so other solutions must be proposed.

You're right, doesn't matter what bearings we use, the problem still persists with oil starvation and dirty oil. And bearing choice is more of a personal choice/preference. I just happen to be the guy who opens up the engine every 20-30k, so yea, which ever bearing I put in there, I have ample of time to react if some bad primitive wear were to happen. I went with trimetal bearings for my build, and opened it up after 20k miles of use and found zero scratch on that thing; henceforth the recommendation. Note that I also changed the oil 6 times during this 20k mile bout.