M50 Rebuild: Bearing Clearances

[CMBusch]

I've been rebuilding a M50 that I plan on putting in my E30. I'm in the process of measuring the bearing clearance for the main and rod journals. As far as I know, main bolts and rod bolts are TTY and I seemed to have lost/thrown out the old bolts. If I use new bolts to check the clearances, can they still be used in assembly? Do I need to fully torque down the bolts to get accurate measurements? Any help would be greatly appreciated.

[Sh3rpak!ng]

I've been rebuilding a M50 that I plan on putting in my E30. I'm in the process of measuring the bearing clearance for the main and rod journals. As far as I know, main bolts and rod bolts are TTY and I seemed to have lost/thrown out the old bolts. If I use new bolts to check the clearances, can they still be used in assembly? Do I need to fully torque down the bolts to get accurate measurements? Any help would be greatly appreciated.

That's a bummer. Yes they are both TTY. And yes you do need to fully torque the caps down to get accurate clearance measurements which means you shouldn't be reusing the new stuff after its already been fully torqued.

I'd see if there's someone willing to send you a set of old bolts, or find a yard and pull all those bolts out, or just buy a full 2nd set.

[CMBusch]

Damn, I was hoping to avoid that as they are $150 for each full set. I have another complete M50, but I didn't want to take it apart until I got this one back together. Since they sell both bolts individually, I think I'll buy two extra of each and sacrifice them to get the measurements one by one. That would work right? Regardless, thanks for the feedback.

[Sh3rpak!ng]

Damn, I was hoping to avoid that as they are $150 for each full set. I have another complete M50, but I didn't want to take it apart until I got this one back together. Since they sell both bolts individually, I think I'll buy two extra of each and sacrifice them to get the measurements one by one. That would work right? Regardless, thanks for the feedback.

Buy a set of ARP main studs and ARP head studs and then sell the oem bolts to offset the cost? I think the ARP mains are the same price as the oem mains (wish I knew that when I was building mine)

[pazi88]

Buy a set of ARP main studs and ARP head studs and then sell the oem bolts to offset the cost? I think the ARP mains are the same price as the oem mains (wish I knew that when I was building mine)

How come? Oem main bolts are like dollar a piece. The set of arp's 120-150? And the arp main bolts suck ass because they distort main caps if torqued to the manufacturer spec.

And you could also use regular m10x1,5x75 grade 10.9 bolts that can be get from any bolt store.

[Sh3rpak!ng]

How come? Oem main bolts are like dollar a piece. The set of arp's 120-150? And the arp main bolts suck ass because they distort main caps if torqued to the manufacturer spec.

And you could also use regular m10x1,5x75 grade 10.9 bolts that can be get from any bolt store.

Dunno where you bought the main bolts from but the best price I found was $7.50 per bolt x14 = $105 for the set. First I've heard of the distortion.. good to know.

A regular m10 grade 10.9 might be usable, but I'm not sure I would trust the quality compared to oem. Maybe I'm just paranoid.

[philakamrbean]

I'm looking into this actually as well.

I've found the rod bolts for ~3.50 each on autohausaz.com, but the main bolts are ~7ish each. Are the M54 main and rod bolts the same as the m50?

[CMBusch]

Buy a set of ARP main studs and ARP head studs and then sell the oem bolts to offset the cost? I think the ARP mains are the same price as the oem mains (wish I knew that when I was building mine)

Yeah I haven't even ordered any of the bolts yet, but I was thinking I could use the extra pairs of OEM bolts to get the measurements or the M10 10.9 bolts for the main cap measurments.

How come? Oem main bolts are like dollar a piece. The set of arp's 120-150? And the arp main bolts suck ass because they distort main caps if torqued to the manufacturer spec.

And you could also use regular m10x1,5x75 grade 10.9 bolts that can be get from any bolt store.

I don't know where you're finding those prices, but send me a link! Good looking out with those main bolts though. Do you know how ARP head bolts are? I guess I could use the M10 10.9 bolts to get the measurements but I wouldn't put them in the engine. (I'm paranoid too.)

[pazi88]

Dunno where you bought the main bolts from but the best price I found was $7.50 per bolt x14 = $105 for the set. First I've heard of the distortion.. good to know.

A regular m10 grade 10.9 might be usable, but I'm not sure I would trust the quality compared to oem. Maybe I'm just paranoid.

I order my parts from bmw part stores at germany.

Did you check the bearing clearnces with the arp specified torque? I have heard that it's quite common.

And the oem main bolts are just regular bolts. So you can get those from bolt store. Just make sure those aren't some cheap chinese ones where the grade is ofter totally different than it should be. The rod bolts are bit special so those need to be oem.

[Sh3rpak!ng]

I order my parts from bmw part stores at germany.

Did you check the bearing clearnces with the arp specified torque? I have heard that it's quite common.

And the oem main bolts are just regular bolts. So you can get those from bolt store. Just make sure those aren't some cheap chinese ones where the grade is ofter totally different than it should be. The rod bolts are bit special so those need to be oem.

Ahh just saw you're in Finland. I guess ordering from BMW parts stores in Germany is cheaper? Lucky you!

I didn't do the ARP mains in my build so I didn't measure with them.

Again, good to know about the oem mains being able to use a quality m10 10.9 bolt. For anyone looking for a good source, you can order from mcmaster carr, m10x75mm (assuming 1.5 thread pitch) is $10 for 10 bolts. Belmetric also has assorted sizes and grades, their m10x75 10.9s are $1.29 ea https://www.belmetric.com/10x15-coar...io1l9bdgbdjs76

[pazi88]

Maybe Offtopic but I'm not aware if there is problem of ordering stuff from germany to US. At least the shipping from US to europe is quite reasonable priced. And many sellers offer world wide shipping.

[Jaker]

I could probably send you some used rod and main bolts for the cost of shipping. I plan to be south of the border shortly and can drop them in a Priority Mail Flat Rate box for $7.

Jacques

[CMBusch]

I could probably send you some used rod and main bolts for the cost of shipping. I plan to be south of the border shortly and can drop them in a Priority Mail Flat Rate box for $7.

Yeah that'd be great! If you can, pm me and we can sort it out.

Maybe Offtopic but I'm not aware if there is problem of ordering stuff from germany to US. At least the shipping from US to europe is quite reasonable priced. And many sellers offer world wide shipping.

From what I know, there aren't any issues with shipping. The problem for most of us in North America is that we don't really know where to look and/or we don't speak German. I saw this video from an E30-related YouTube channel that has useful info. Aside from that however, I know nothing else on the topic of buying parts overseas.

Ahh just saw you're in Finland. I guess ordering from BMW parts stores in Germany is cheaper? Lucky you!

I didn't do the ARP mains in my build so I didn't measure with them.

Again, good to know about the oem mains being able to use a quality m10 10.9 bolt. For anyone looking for a good source, you can order from mcmaster carr, m10x75mm (assuming 1.5 thread pitch) is $10 for 10 bolts. Belmetric also has assorted sizes and grades, their m10x75 10.9s are $1.29 ea https://www.belmetric.com/10x15-coar...io1l9bdgbdjs76

Yeah this is really helpful to know. The more I think about it, the more ok I am with using 10.9 bolts.

I'm looking into this actually as well.

I've found the rod bolts for ~3.50 each on autohausaz.com, but the main bolts are ~7ish each. Are the M54 main and rod bolts the same as the m50?

Possibly. Apparently the M50 uses two different types of rod bolts, one of which is used on the M54. Its part#11241739728 which is where I think you're getting the $3.50 from. Unfortunately, I need the ones that are $7.50 each (part#11241713342).

[M3PO]

Could be worse, I'm building an early S54 where the rod bolts are to be reused, are not available separately, and must be returned to THE hole they came out of. Oops...lol

[CMBusch]

Could be worse, I'm building an early S54 where the rod bolts are to be reused, are not available separately, and must be returned to THE hole they came out of. Oops...lol

:shock: Yeah, I did the same thing with the lifters in my M50. I'm sure there are other things that are supposed to retain their placement as well but I've come to the conclusion that it'll be fine.