Engine build questions,, Bedplate???

[Bnks334]

So the tang on the back of the bearing doesn't locate the bearing shell in the saddle?

I wouldn't really say things were taken out of context. I think it's more that the truth was stretched a bit to make it seem like ABR is offering people something exclusive and an "extra" that others don't (marketing bullet point). Then bold assumptions like "BMW laser robots" were made. People regurgitated it as fact.

Yeah, I fully understand that machining on an aluminum block is more complicated than an iron one. That's where torque plates for bore jobs and special care using techniques to "bend" the bed-plate back into spec to true up the line bore might be necessary. I don't see how that applies to getting the alignment of the bearings correct in a block that measures out to be true. That's where the truth is stretched.

If you measure out axial play to be in-spec then the bed-plate and block are "aligned" as good as they are going to get in terms of the bearings matching up perfectly side-to-side. If not, you would have no end-play.

If anyone wants to see a BMW engine be assembled you can see it from start to finish on youtube:

or

First, the bed-plate looks to be a completely separate casting from the block. You can see in multiple points of the video that the crank bore is open/unfinished until the block is mated to a bed-plate down the assembly line. Hence why the bed-plate doesn't actually align with the block from a visual and external/perspective to any degree of accuracy. Second, the robotic arm used to drop the bed-plate and cylinder head in place is so that the assembly line doesn't require manual labor. There is no laser-alignment taking place (at least not down to accuracy like .001")... the machine just lines up the mating parts with the dowel pins that the head/bedplate drop onto. In order for any accuracy to be retained during this step, the head and bed-plate would need to be bolted down right then and there. They aren't. They get rough housed right down the assembly line where things are measured out and bolted down in a later step. I don't even see how you could ensure the bearings line up right.. You would need x-ray vision to see through the bridge of the bed plate or the top deck of the block lol It's just not even a concern...

Fast forward to @4:14 if you want to see them revving the snot out of brand new freshly assembled motors. So much for "breaking-in" motors gently.

 

[Rob09msport]

So the tang on the back of the bearing doesn't locate the bearing shell in the saddle?

I wouldn't really say things were taken out of context. I think it's more that the truth was stretched a bit to make it seem like ABR is offering people something exclusive and an "extra" that others don't (marketing bullet point). Then bold assumptions like "BMW laser robots" were made. People regurgitated it as fact.

Yeah, I fully understand that machining on an aluminum block is more complicated than an iron one. That's where torque plates for bore jobs and special care using techniques to "bend" the bed-plate back into spec to true up the line bore might be necessary. I don't see how that applies to getting the alignment of the bearings correct in a block that measures out to be true. That's where the truth is stretched.

If you measure out axial play to be in-spec then the bed-plate and block are "aligned" as good as they are going to get in terms of the bearings matching up perfectly side-to-side. If not, you would have no end-play against the thrust bearing surface in one direction or the other.

If anyone wants to see a BMW engine be assembled you can see it from start to finish on youtube:

or

First, the bed-plate looks to be a completely separate casting from the block. You can see in multiple points of the video that the crank bore is open/unfinished until the block is mated to a bed-plate down the assembly line. Hence why the bed-plate doesn't actually align with the block from a visual and external/perspective to any degree of accuracy. Second, the robotic arm used to drop the bed-plate and cylinder head in place is so that the assembly line doesn't require manual labor. There is no laser-alignment taking place (at least not down to accuracy like .001")... the machine just lines up the mating parts with the dowel pins that the head/bedplate drop onto. In order for any accuracy to be retained during this step, the head and bed-plate would need to be bolted down right then and there. They aren't. They get rough housed right down the assembly line where things are measured out and bolted down in a later step. I don't even see how a machine could ensure the bearings line up right.. It would need x-ray vision to see through the bridge of the bed plate or the bores of the block lol

Fast forward to @4:14 if you want to see them revving the snot out of brand new freshly assembled motors.

Textbook definition of schooling see above

 

[Alex@abrhouston]

The first video doesn't even have a bedplate lol. The big thing you're missing I think, is that these are virgin engines, that have not been stressed, hurt, damaged, or put out of service. The bedplate and block are line honed and machined as one piece. When a crank spins a bearing and throws 3 journals out of plane 2-3 different directions, it also does this to the block line bore. This makes the block incredibly difficult to get back to square again. I've fixed plenty of engines that were "rebuilt" and ended up wiping out a crank bearing because one journal was out compared to the rest. We can argue all you want, I've put together enough N54's and N55's to know what works and what doesn't.

 

[Bnks334]

The first video doesn't even have a bedplate lol. The big thing you're missing I think, is that these are virgin engines, that have not been stressed, hurt, damaged, or put out of service. The bedplate and block are line honed and machined as one piece. When a crank spins a bearing and throws 3 journals out of plane 2-3 different directions, it also does this to the block line bore. This makes the block incredibly difficult to get back to square again. I've fixed plenty of engines that were "rebuilt" and ended up wiping out a crank bearing because one journal was out compared to the rest. We can argue all you want, I've put together enough N54's and N55's to know what works and what doesn't.

OK so you concede that the "proprietary method" you're noting has to do with machining to correct an an out-of-spec line bore and is NOT necessary to mate the bed-plate to the block correctly as your comments suggested? Question, do you guys do the machining, or, is it outsourced?

The video doesn't show a bed-plate is my exact point. It's a separate casting not mated to any particular block. The external casting dimensions are surely not held to any significantly high level of accuracy. And, I pointed out that my own bed plate DID NOT line up perfectly with my block as a working example. It's not like BMW is cutting the bed-plate off a 1-piece block and the two-halves are vin matched... Any attempt to "brute force" the bed-plate into alignment with a "jig" would've been very counter-productive. Is it me interpreting things wrong? Because, I am pretty sure that's the gist of what the ABR comments were claiming... and that is how people are interpreting them. Pictures ensued of people bolting flimsy aluminum to the external motor mount holes of their block to "align" their bed-plate. If you're comments are misleading people do things like this, then clarify them, because it makes NO sense. And, I will continue to debate you as being dead wrong since you still haven't provided a single thing to support this assertion whereas I have provided plenty of logical counter-points.

I left the door open for you to concede/agree that your comments were more in regard to the proprietary methods used to ensure the line bore is straight and instead you are trying to deflect from making any misleading comments... I am done with this as text over the internet never plays out as constructive dialog.

 

[Bnks334]

Sorry the top video DOESN'T show what I referenced in regard to the bed plate casting. The engine in the first video got traditional caps. Bottom N20 video doesn't show the casting either. Point there though was the the external casing gives you 0 idea as to whether your bearings are aligned.

Here is the assembly of a Mercedes AMG diesel engine. Dude grabs a bed plate and bolts it up. No "laser alignment" or external jig to be seen anywhere. Can't say for sure in regard to the n5x since I don't have a video, but I don't see how it would be any different.

 

[Optigrab]

Sorry the top video DOESN'T show what I referenced in regard to the bed plate casting. The engine in the first video got traditional caps. Bottom N20 video doesn't show the casting either. Point there though was the the external casing gives you 0 idea as to whether your bearings are aligned.

Here is the assembly of a Mercedes AMG diesel engine. Dude grabs a bed plate and bolts it up. No "laser alignment" or external jig to be seen anywhere. Can't say for sure in regard to the n5x since I don't have a video, but I don't see how it would be any different.

I would imagine there is some difference in rebuilding an engine and assembling one at the factory.
The factory would be all new parts

 

[Hydra Performance]

The bedplate to block alignment only becomes an issue on an N5x in the event of a nasty bearing failure or rod knock with resultant crankshaft warpage/bending.

 

[Alex@abrhouston]

I never condoned the aluminum plates you mentioned, and that's certainly not what we do to align it. Whoever decided to make those, utilize them, then say we do that as well, is well.... wrong. I'm not being defensive, just clarifying what was said, and what we do. Don't worry, I have thick skin. Yes, your correct- to fix an out of line crankshaft bearing bore is what I'm referring to. The thing I think you're skipping over is the measurement of the bearing bore for each journal, and how BMW has selected a specific colored bearing for each shell to make up for variances in the clearances from mass production. Specifically saying- you're not being shown where the bedplate was on that specific block, machined, measured, unbolted, crankshaft measured, differences compared, bearings selected, bearings installed, and then "bedplate slapped on"
I can't say for Mercedes if they do the same ridiculous bearing assortment like BMW does, either. I don't have experience in building Merc engines.

A traditional engine is going to have married main caps as well, specific to that engine, that journal, and are line bored and honed in the same fashion- bolted/machined/honed/marked/measured, clearance checked on crank to main, taken apart then assembled.

Youtube videos aren't showing the entire procedure.

 

[Alex@abrhouston]

The bedplate to block alignment only becomes an issue on an N5x in the event of a nasty bearing failure or rod knock with resultant crankshaft warpage/bending.

This is typically the case. Rod or main bearing failure, no matter how insignifigent will typically throw the line bore of the block and the crank off. A bad rod journal spin will sometimes throw off the two journals next to it- sometimes 3. Occasionally it's not even worth trying to save a block or crank- just too much work involved to make it whole again.

 

[Bnks334]

I would imagine there is some difference in rebuilding an engine and assembling one at the factory.
The factory would be all new parts

Right, and what does that have to do with needing a jig to bolt the bed-plate up?

The bedplate to block alignment only becomes an issue on an N5x in the event of a nasty bearing failure or rod knock with resultant crankshaft warpage/bending.

If they use some special jig/plate to fix a damaged block then so be it, but, you surely don't need any special jig to put a bed-plate on a block. You don't need any special jig to get bearing diameter, crank diameter, and bearing eccentricity measurements needed to determine clearances. You don't need a special jig to ensure crank end-play is within spec. And, you don't need any special jig to measure whether the crank bore is true/square. That phrasing and the inferences being made are what was being debated.