[oilcrankinject]

My motor is at a machine shop. They told me that I would need 0.5mm oversized con rod bearings.

MMP has yet to tell me the sizes of their oversized bearings.
I have heard bad things about King bearings.

Are there any other companies that offer oversized con rod bearings?

[nissubaru]

99% sure MMP resells King bearings as per JonEQuest

https://www.e90post.com/forums/showthread.php?t=1550150

Supposedly he bought King bearings from MMP so I would assume that's what he has. IMO his price is a ripoff.

I have King bearings installed, standard size. Car runs great, only reason I could see someone having issues with the King bearings are if they bought the wrong size or they fucked up the installation somehow.

[dpaul]

ACL makes them in std, 0.025 and 0.25 oversize:
https://www.aclraceseries.com/images/catalog.pdf

I don't have personal experience with ACL but some E90 M3/S65 owners have installed their rod bearings and reported good outcomes

[feuer]

Originally Posted by svtfast

My motor is at a machine shop. They told me that I would need 0.5mm oversized con rod bearings.

MMP has yet to tell me the sizes of their oversized bearings.
I have heard bad things about King bearings.

Are there any other companies that offer oversized con rod bearings?

If you are cutting the crank you will need undersized rod bearings. I'm not sure they make them 0.5 for n54. What is the reason for this? Is the crank damaged? If so what is the cost difference between cutting the crank vs getting good used crank?

[oilcrankinject]

Well I ended up needing 0.010 undersized crank bearings as well and NO ONE has them in stock, world wide. I am going to pull a crank from JY this weekend. I will measure it to make sure it does not have rod knock.

$56 for a used crank. At least with that I can use standard size main bearings.

Old crank had scarring from the rod knock.

[feuer]

Originally Posted by svtfast

Well I ended up needing 0.010 undersized crank bearings as well and NO ONE has them in stock, world wide. I am going to pull a crank from JY this weekend. I will measure it to make sure it does not have rod knock.

$56 for a used crank. At least with that I can use standard size main bearings.

Old crank had scarring from the rod knock.

How are the rods? If the crank is damaged is possible the rods big ends are widen and out of round.

[Ozzie335i]

As the STD King bearings provide 1 mm more clearence than stock you'd most probably be ok. If still concerned, ask sales. I also went with the King bearings on a 530 + whp N55 as a proactive swap at 68 k miles. Still together. Obviously new rod bolts and Plastigage is your friend.

[bbnks2]

Originally Posted by Ozzie335i

As the STD King bearings provide 1 mm more clearence than stock you'd most probably be ok. If still concerned, ask sales. I also went with the King bearings on a 530 + whp N55 as a proactive swap at 68 k miles. Still together. Obviously new rod bolts and Plastigage is your friend.

I feel like you said this elsewhere as well. STD means standard as in producing stock clearance. They do not provide any additional clearance. OP needs an undersized bearing, meaning THICKER than stock to account for the crank being cut (made smaller). Also, 1mm is .039" so not sure where you got 1mm from but no way any bearing that is 1mm different than stock will work.

OP needs .25mm undersize bearings (.01"). Usually denoted by a .25 at the end of the part name.

Originally Posted by svtfast

Well I ended up needing 0.010 undersized crank bearings as well and NO ONE has them in stock, world wide. I am going to pull a crank from JY this weekend. I will measure it to make sure it does not have rod knock.

$56 for a used crank. At least with that I can use standard size main bearings.

Old crank had scarring from the rod knock.

OP, if you really need them that quickly then I would message sellers on Ebay.

KOLBENSCHMIDT MAIN bearings available at the link below. Seller says they have .25 and .5 available on request. $70.60 + ~$60 or so for DHL express and you'll have them within a few days.

https://www.ebay.com/itm/BMW-N54-B30...QAAOSwoW1cdFC0

OP are you sure you need Main bearings though? or, just rod bearings? Did you damage main bearings? Just curious why the machine shop decided it was necessary to cut the main bearings journals as well... The few engines I've pulled bearings out of did not hurt the main bearings. A quick polish is all that was required for the main bearing journals.

[Ozzie335i]

"OP needs .25mm undersize bearings (.01"). Usually denoted by a .25 at the end of the part name."

This is what I was referencing, but screwed up on the mm / inch thing. The King bearings provide .020" clearence vs .010" for stock BMW clearence, so I was wrong in them possibly working. They likely have undersized sizes as well. In reality whoever did the cutting should have known what bearing sizes are available before doing so.

[dpaul]

I am no expert at engine rebuilding and found the terminology used in this thread quite confusing. It took me a while to wrap my head around it so I'm throwing this out there just for the fuck of it.

Just applying logic, it seemed to me that if one has a damaged rod bearing, one grinds it making the bearing journal undersized relative to the standard journal size. Therefore, the new rod bearing itself would have to oversized, not undersized, in order to establish the proper clearance with the rod journal.

But as far as I can tell from Googling, that is not the way the words are used at all. There is not much logic to their usage (IMHO) but there is consistency.

So: bearings have an inside diameter (the surface that is close to the crankshaft journal) and an outside diameter (the surface that is close to the rod, the crankcase or the bearing cap. If the crank is ground, it is fitted with a bearing that is defined as undersized. If the rod or crankcase are line bored, they are fitted with bearings that are defined as oversized.

Thus a bearing can be both undersized and oversized at the same time!

Then there is the liberal use of the word "clearance". As far as I am aware, "clearance" refers to the difference in size between a bearing journal and the inside surface of the bearing itself. Bearings can in some cases be ordered to increase the "clearance" (defined as I've just described). Why would one do that? One relevant example is BMW, who went against industry norms and set an unusually small rod bearing "clearance" in the S65 (E90 M3 V8) and S54 (E46 M3 inline 6) engines, resulting in many reports of premature rod bearing failure. So some bearing manufacturers, ACL being one, sell bearings for many types of engines that are have increased "clearance" by 0.001" (0.25mm). Many posters (including me) have installed such rod bearings in our S65 engines.

Bearings described above are neither under- nor oversized. It would be referred to having increased "clearance".

Appreciate any feedback to correct my impressions of how all these words should be used.

[oilcrankinject]

Due to some extra shifts at work I wont be able to hit the junkyard until Monday. I am thinking it will be a 5-6 hour job to pull the motor from the car and to take the crank out.

If I can get a used but good crank, I will be able to use standard size bearings.

[nissubaru]

Originally Posted by svtfast

Due to some extra shifts at work I wont be able to hit the junkyard until Monday. I am thinking it will be a 5-6 hour job to pull the motor from the car and to take the crank out.

If I can get a used but good crank, I will be able to use standard size bearings.

You gotta pull that thing yourself?? You sure you're gonna be able to get it out and everything in a junkyard? Not questioning your abilities but we can't even bring a jack to my local u pull

Also, do you have all of the special tools? I'm not 100% positive but I think you need a tool or two to get the head off.

[bbnks2]

Originally Posted by dpaul

I am no expert at engine rebuilding and found the terminology used in this thread quite confusing. It took me a while to wrap my head around it so I'm throwing this out there just for the fuck of it.

Just applying logic, it seemed to me that if one has a damaged rod bearing, one grinds it making the bearing journal undersized relative to the standard journal size. Therefore, the new rod bearing itself would have to oversized, not undersized, in order to establish the proper clearance with the rod journal.

But as far as I can tell from Googling, that is not the way the words are used at all. There is not much logic to their usage (IMHO) but there is consistency.

So: bearings have an inside diameter (the surface that is close to the crankshaft journal) and an outside diameter (the surface that is close to the rod, the crankcase or the bearing cap. If the crank is ground, it is fitted with a bearing that is defined as undersized. If the rod or crankcase are line bored, they are fitted with bearings that are defined as oversized.

Thus a bearing can be both undersized and oversized at the same time!

Then there is the liberal use of the word "clearance". As far as I am aware, "clearance" refers to the difference in size between a bearing journal and the inside surface of the bearing itself. Bearings can in some cases be ordered to increase the "clearance" (defined as I've just described). Why would one do that? One relevant example is BMW, who went against industry norms and set an unusually small rod bearing "clearance" in the S65 (E90 M3 V8) and S54 (E46 M3 inline 6) engines, resulting in many reports of premature rod bearing failure. So some bearing manufacturers, ACL being one, sell bearings for many types of engines that are have increased "clearance" by 0.001" (0.25mm). Many posters (including me) have installed such rod bearings in our S65 engines.

Bearings described above are neither under- nor oversized. It would be referred to having increased "clearance".

Appreciate any feedback to correct my impressions of how all these words should be used.

You're issue is that you're thinking about the bearings too much.

It's not called an "undersized bearing." The beating is thicker to account for the "undersized crankshaft."

The naming is referring to the crankshaft. That is what is machined during the repair. The bearings are made to fit said crank repair. Cutting the crank makes it smaller. It is now undersize vs standard. The nomenclature makes sense.

[bbnks2]

Originally Posted by nissubaru

You gotta pull that thing yourself?? You sure you're gonna be able to get it out and everything in a junkyard? Not questioning your abilities but we can't even bring a jack to my local u pull

Also, do you have all of the special tools? I'm not 100% positive but I think you need a tool or two to get the head off.

Nah no special tools to disassemble the engine. Just the right size sockets to hold the cam or a thin wrench. Defintly not going to happen in a upull though. You'll probably need to buy the engine and disassemble at home.