Dumb Question Thread - No Flaming Allowed

[ATB88]

Just lowering the subframe means that you don't need to drain the power steering system, which equals less mess and work.

To get a good plastigauge measurement, you need to do the full torque procedure. I'm willing to bet that the BMW techs at the dealership did not plastigauge measure clearances before installing the new bearings. It is not in the service bulletin - http://www.siwilson.com/BMW/Service_...20Bulletin.pdf

I did find this BMW service snippet which explains how to use plastigage to measure S54 rod bearing clearances during replacement. Since the torque sequence described is for the M11 bolts, I'm assuming that this is an "old" version of the service bulletin before they moved to the M10 bolts? This suggests to me that it was part of the dealership service procedure earlier on (or maybe for the first of the two service bulletins)? Whether or not they actually did it is another story.

The procedure does say to do a full torque sequence to do the plastigage measurement.

http://www.adkusters.dsmynas.com/Website%20mynas/TIS%20documents%20PDF%20aanvulling/11_24_571.pdf

If they actually do this at the dealership when replacing RBs, then that effectively halves the usable life of the M11 style bolts, which seems concerning.

If it's generally known that you don't have to fully torque to use plastigage properly... how much should I torque if I want to plastigage?

[Slideways]

Another RB question: I'm going to be doing tie rods, steering rack boots, and all the PS lines "while I'm in there"... I see that a lot of people don't completely drop the front sub frame, just lower it. It honestly seems easier to just remove it entirely if you're going to be taking tie rods off anyway? Is there any reason to avoid dropping the whole front subframe off in my case?

Just lowering the subframe means that you don't need to drain the power steering system, which equals less mess and work.

To get a good plastigauge measurement, you need to do the full torque procedure. I'm willing to bet that the BMW techs at the dealership did not plastigauge measure clearances before installing the new bearings. It is not in the service bulletin - http://www.siwilson.com/BMW/Service_...20Bulletin.pdf

[JakeM346]

Another RB question: I'm going to be doing tie rods, steering rack boots, and all the PS lines "while I'm in there"... I see that a lot of people don't completely drop the front sub frame, just lower it. It honestly seems easier to just remove it entirely if you're going to be taking tie rods off anyway? Is there any reason to avoid dropping the whole front subframe off in my case?

well if you’re changing all that anyway than it’s better to remove it. If you just lower it you can keep the tires on and don’t have to wiggle out the tie rod bolts. It’s basically a bit less work and most people do it like this because the original BMW recall specified that procedure.

[ATB88]

Another RB question: I'm going to be doing tie rods, steering rack boots, and all the PS lines "while I'm in there"... I see that a lot of people don't completely drop the front sub frame, just lower it. It honestly seems easier to just remove it entirely if you're going to be taking tie rods off anyway? Is there any reason to avoid dropping the whole front subframe off in my case?

[ATB88]

Less is more here. Try not to touch the crank journal or dry bearing surface. Keep one pair of clean gloves for bearing installation/lubrication and another pair for removing the dirty stuff - oil pickup tubes, pump, etc.

Bearings usually come in a sealed container, so they do not need to be cleaned. You can wipe down the backside of the bearing if you must and you can use brake cleaner to remove oil from the rod and cap before installing the new bearings. The surface, at least for BMW bearings, has a break-in layer that is very soft. Light surface marks are not an issue, only deep gouges. Your nail is not going to do much when engine builders use micrometers with metal tips to measure bearing clearance. Those cause insignificant marks in the bearings all the time.

When using factory bolts, clean and lightly oil the head of the bolt and threads before install.

You'll see videos of people lubricating the backside of the bearings and doing all sorts of weird stuff. Don't do that. Just follow the BMW procedure and you'll be good. M539 has a few good bearing install videos as well.

Awesome, thanks for this. I figured as much about the light surface marks in the breakin layer, just wanted to be sure.

I have an early motor, so the plan is to re-use the factory M11 bolts that are in there (assuming that I do indeed find M11s when I open it up -- I have BMW M10s on hand in case I find M10s in there, and also ARP replacements for M11s if somehow for some reason something goes wrong re-using the M11s and I need a plan B). When you say lightly oil the head and threads, I assume this is, like, get some 10W60 on my fingers, and touch the threads and underneath of the head (which will make contact with the rod when tightened)? I was actually wondering this -- if the torque spec/sequence depends on the bolt going in dry, or if it accounts for the fact that everything's so oily in there that there's going to be oil on the threads. Along the same lines, I was also wondering if I should clean out the threads in the rod with brake cleaner, but it sounds like no?

[Slideways]

A few more dumb questions leading up to my rod bearing job, mostly about what if anything hurts the new bearings while I'm installing:

-to what extent is it okay for me to touch the rod bearing surfaces with bare hands?
-I noticed that lightly dragging my fingernail across one caused visible scuff, I assume this isn't a big deal?
-Should I be wiping the new bearings down with brake cleaner before I slather them in assembly lube and put them in? or am I to trust them right out of the package?
-I've seen in some DIY videos that people will clean the crank surface that the bearings ride on. I saw one guy use a mild sandpaper? What's the best way to make sure the crankshaft surface is clean and ready for the new bearings?

Sorry if these seem like silly questions, this just feels like a job where a dumb oversight could lead to disaster.

Less is more here. Try not to touch the crank journal or dry bearing surface. Keep one pair of clean gloves for bearing installation/lubrication and another pair for removing the dirty stuff - oil pickup tubes, pump, etc.

Bearings usually come in a sealed container, so they do not need to be cleaned. You can wipe down the backside of the bearing if you must and you can use brake cleaner to remove oil from the rod and cap before installing the new bearings. The surface, at least for BMW bearings, has a break-in layer that is very soft. Light surface marks are not an issue, only deep gouges. Your nail is not going to do much when engine builders use micrometers with metal tips to measure bearing clearance. Those cause insignificant marks in the bearings all the time.

When using factory bolts, clean and lightly oil the head of the bolt and threads before install.

You'll see videos of people lubricating the backside of the bearings and doing all sorts of weird stuff. Don't do that. Just follow the BMW procedure and you'll be good. M539 has a few good bearing install videos as well.

[ATB88]

A few more dumb questions leading up to my rod bearing job, mostly about what if anything hurts the new bearings while I'm installing:

-to what extent is it okay for me to touch the rod bearing surfaces with bare hands?
-I noticed that lightly dragging my fingernail across one caused visible scuff, I assume this isn't a big deal?
-Should I be wiping the new bearings down with brake cleaner before I slather them in assembly lube and put them in? or am I to trust them right out of the package?
-I've seen in some DIY videos that people will clean the crank surface that the bearings ride on. I saw one guy use a mild sandpaper? What's the best way to make sure the crankshaft surface is clean and ready for the new bearings?

Sorry if these seem like silly questions, this just feels like a job where a dumb oversight could lead to disaster.

[ATB88]

https://www.ecstuning.com/BMW-E46-M3...iper/Hardware/

Thank you!!

[oceansize]

Thanks all for the thoughts!

Completely unrelated, I have a p/n request: I pulled my windshield wiper arms off the other day to install a new cowl. I found that sitting just under where the arms attach to the spindles, there seemed to be some sort of bushign and/or plastic washer that was all busted and degraded. I would like to replace before putting the wiper arms back on, but no idea how to find them?

https://www.ecstuning.com/BMW-E46-M3-S54_3.2L/Exterior/Wiper/Hardware/

[ATB88]

Thanks all for the thoughts!

Completely unrelated, I have a p/n request: I pulled my windshield wiper arms off the other day to install a new cowl. I found that sitting just under where the arms attach to the spindles, there seemed to be some sort of bushign and/or plastic washer that was all busted and degraded. I would like to replace before putting the wiper arms back on, but no idea how to find them?

[Slideways]

No issues getting bearings done with the 3/8ths.

The problem with torquing anything like this on one's back is sliding around on the floor. The trick is finding something to brace against and keep from sliding around during the angle torque. A loose wheel with tire laying flat on the floor is a good option.

The 3/8ths is much more useful for the home DIYer. For a mechanic doing bearings every few days, the 1/2" is the way to go.

As crazy as it sounds, the 3/8ths can do head bolts. Final 90 angle comes out to around 80 ft-lbs, but it is quite a workout. Probably best to borrow a 1/2" for this.

M10 rod bolts register around 65 ft-lbs on the final 105 angle.

[George Hill]

. Also only having to do a single 70 degree sweep hopefully makes it manageable.

Every single RB I have done so far I have used this gauge. Its not the cheapest option, but there is no reason why you couldn't use a simple angle gauge (since I saw you looking for a techangle).

https://stahlwille.com/en_de/products/detail/856162

[ATB88]

I've probably done 75+ sets of rod bearings, maybe more? The torque is 5nm, 30nm and then an angle. I use me 3/8" torque wrench to do the initial set, then 30nm. I then use a mechanical dial gauge and and a 1/2" ratchet to do the angle. *I have use the 3/8" techangle to do the angle but its not very fun. If you have the front suspension hanging and not removed you'll be dealing with a lot of obstacles and that will influence your wrench size as well.

I actually just got a 1/2" techangle and will do my first set of bearings with it in the next week or two. I will still use the 3/8 torque wrench for the 30nm though

Thanks for chiming in. My hope is that the flex head on the 1/2" techangle will allow me to work around geometric constraints. Also only having to do a single 70 degree sweep hopefully makes it manageable.

If anyone else has experiences using the 3/8" or 1/2" techangles to do RBs with suspension in and the car on jackstands, would be grateful to hear!

[George Hill]

I've probably done 75+ sets of rod bearings, maybe more? The torque is 5nm, 30nm and then an angle. I use me 3/8" torque wrench to do the initial set, then 30nm. I then use a mechanical dial gauge and and a 1/2" ratchet to do the angle. *I have use the 3/8" techangle to do the angle but its not very fun. If you have the front suspension hanging and not removed you'll be dealing with a lot of obstacles and that will influence your wrench size as well.

I actually just got a 1/2" techangle and will do my first set of bearings with it in the next week or two. I will still use the 3/8 torque wrench for the 30nm though

[ATB88]

Right, sorry for the confusion, what I am saying is i don't know if the torque for the "older" bolts is the same of not.
For what its worth I did the RB's on my E63 M6 a few months ago and needed the 1/2". The torque for those was 6nm, 20nm, 130°, very similar.

I would get an opinion from someone else but it felt like for me, someone of "average" strength the 3/8" wrench maybe could have worked but I really don't think I would have managed to do each bolt with just one pass.
It's got to be something with torquing above your head side to side not up/down where you are more firmly planned.

Ah, got it. Yeah the torque sequence on the M10 (newer) bolts seems like it would require applying more torque -- just first pass is 105 degrees rather than just a single pass of 70 degrees for the M11 bolts. But it's not clear how much more "actual" torque I'll need to be applying to get where I need to be with one vs the other. So, yeah, I see, maybe it is possible to get away with a 3/8" techangle. I don't think I want to take the chance though. I think I'll just get the 1/2" techangle and then sell it on if I really think it would be nice to have a 3/8" for general use.

Thanks for the sanity check!