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      10-30-2019, 08:50 PM   #23
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Thanks for the replies, all. I honestly don’t know if 120 vs 140 Nm makes a critical difference. Essentially, you don’t want to overtighten with an unrestricted impact gun and stress the threads, and you don’t want to undertighten and have this happen:

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      07-02-2022, 10:50 AM   #24
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Just a side note on this as I was swapping the wheels just now. 101 lb. ft. / 140 Nm is not a lot of force at all. Kinda surprising
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      07-02-2022, 02:25 PM   #25
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Quote:
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Just a side note on this as I was swapping the wheels just now. 101 lb. ft. / 140 Nm is not a lot of force at all. Kinda surprising
Since getting my FI-R's and BBS lugs I've been wondering about this. Is it the OEM lug that requires 101? The OEM wheel? The fact that BMW expects guys to track the car? The heavy weight of the stock combo? I don't have stock lugs or wheels, and I don't track my car. And my set up is super light. I wonder if it matters at all for me. Our Acura SUV is heavier by a long shot and has heavier wheels and the OEM specs are 80 ft lbs.
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      07-03-2022, 03:00 PM   #26
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Quote:
Originally Posted by ///MPhatic View Post
Since getting my FI-R's and BBS lugs I've been wondering about this. Is it the OEM lug that requires 101? The OEM wheel? The fact that BMW expects guys to track the car? The heavy weight of the stock combo? I don't have stock lugs or wheels, and I don't track my car. And my set up is super light. I wonder if it matters at all for me. Our Acura SUV is heavier by a long shot and has heavier wheels and the OEM specs are 80 ft lbs.
Don't overthink it....
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      07-03-2022, 03:34 PM   #27
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Don't overthink it....
I wouldn't, other than the fact that it was one torque for many years and they changed it. It's natural for me to want to know why. It's a sickness I have.
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      07-03-2022, 05:19 PM   #28
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Quote:
Originally Posted by ///MPhatic View Post
I wouldn't, other than the fact that it was one torque for many years and they changed it. It's natural for me to want to know why. It's a sickness I have.
Larger fastener, higher torque spec. I'd torque to 140. But honestly, for wheels, anything works as long as it's not loose and not stripping the threads and able to be removed. I go 10% higher because I don't know if my wrench is accurate and there's probably not going to be an issue with a bit more torque. Most shops use an impact gun and put them on so tight they are nearly impossible to take off and you rarely hear of issues.
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      07-03-2022, 07:25 PM   #29
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Quote:
Originally Posted by chris719 View Post
Larger fastener, higher torque spec. I'd torque to 140. But honestly, for wheels, anything works as long as it's not loose and not stripping the threads and able to be removed. I go 10% higher because I don't know if my wrench is accurate and there's probably not going to be an issue with a bit more torque. Most shops use an impact gun and put them on so tight they are nearly impossible to take off and you rarely hear of issues.
I personally always do 140 nm, 10% higher in torque should be fine as well.
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      07-03-2022, 09:44 PM   #30
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Quote:
Originally Posted by chris719 View Post
Larger fastener, higher torque spec. I'd torque to 140. But honestly, for wheels, anything works as long as it's not loose and not stripping the threads and able to be removed. I go 10% higher because I don't know if my wrench is accurate and there's probably not going to be an issue with a bit more torque. Most shops use an impact gun and put them on so tight they are nearly impossible to take off and you rarely hear of issues.
If a shop uses an impact on my car I don't go back.

I think for my purposes 80 ft/lb would be just fine, so going 101 is really over-torqued a bit.
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      07-03-2022, 10:49 PM   #31
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Quote:
Originally Posted by ///MPhatic View Post
If a shop uses an impact on my car I don't go back.

I think for my purposes 80 ft/lb would be just fine, so going 101 is really over-torqued a bit.
I would do what BMW specifies, because these are wheel bolts not just lug nuts, this means they have to support the weight of the car as well as hold the wheel on. So if it's too loose vibrations over time could cause the bolts to back out and this can lead to very terrible consequences.
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      07-03-2022, 11:00 PM   #32
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Quote:
Originally Posted by ///MPhatic View Post
If a shop uses an impact on my car I don't go back.

I think for my purposes 80 ft/lb would be just fine, so going 101 is really over-torqued a bit.
As F87source mentioned, you don't really have "your purposes". There is a spec for the bolt and that's it, really. There is no advantage to undertightening it. It's not like an aluminum drain pan bolt or something easily damaged. Most dealers probably hit it with an absolute ton of torque.
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      07-03-2022, 11:32 PM   #33
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Quote:
Originally Posted by chris719 View Post
As F87source mentioned, you don't really have "your purposes". There is a spec for the bolt and that's it, really. There is no advantage to undertightening it. It's not like an aluminum drain pan bolt or something easily damaged. Most dealers probably hit it with an absolute ton of torque.
Yeah I'd rather not have the wheel fall off.

Also this change in torque spec occurred when bmw went to the stronger m14 bolt on the F series, so follow what bmw specs no need to make up any random torque values.


Also this post from earlier has a table showing the appliciable torque specs for bolt sizes and grades, it shows that even on a grade 8.8 bolt over 100 ft lbs of torque is acceptable: https://f87.bimmerpost.com/forums/sh...2&postcount=17
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      07-04-2022, 02:34 PM   #34
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Quote:
Originally Posted by F87source View Post
I would do what BMW specifies, because these are wheel bolts not just lug nuts, this means they have to support the weight of the car as well as hold the wheel on. So if it's too loose vibrations over time could cause the bolts to back out and this can lead to very terrible consequences.
Well, you know I'll do what you tell me, I'm just being a bit cautious because I'm not sure my torque wrench is spot on, and I don't use BMW lugs, I use BBS 2-piece.


Quote:
Originally Posted by chris719 View Post
As F87source mentioned, you don't really have "your purposes". There is a spec for the bolt and that's it, really.
Yeah, respectfully I don't agree with that. Many things are tweakable taking usage into account. The 70 mph speed limit is for mini-vans and Ferrari's? I don't believe that for a second, and I certainly believe that if you're driving a car normally things are different than racing it, and BMW absolutely considered this car a weekend racer.

I'll use the 101, but I'd need hard data to support that it's better for a light wheel/tire combo with BBS lugs and no track days vs the stock heavy combo, stock lugs and the probability of track days.
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      07-04-2022, 03:49 PM   #35
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Quote:
Originally Posted by ///MPhatic View Post
Well, you know I'll do what you tell me, I'm just being a bit cautious because I'm not sure my torque wrench is spot on, and I don't use BMW lugs, I use BBS 2-piece.




Yeah, respectfully I don't agree with that. Many things are tweakable taking usage into account. The 70 mph speed limit is for mini-vans and Ferrari's? I don't believe that for a second, and I certainly believe that if you're driving a car normally things are different than racing it, and BMW absolutely considered this car a weekend racer.

I'll use the 101, but I'd need hard data to support that it's better for a light wheel/tire combo with BBS lugs and no track days vs the stock heavy combo, stock lugs and the probability of track days.
It’s got nothing to do with the wheel and tire combo or how you drive. It’s determined by required clamp load and bolt diameter. BMW uses the same spec for this hardware on every car it’s used on. They changed the spec when they changed the bolts. There’s always margin so I’m guessing your wheels won’t fall off at 80, but you never explained what you hope to gain by undertightening them.

I understand what you mean when it comes some other specs where we understand the design intent well and have other goals, but I truly don’t see what less torque does here other than increase the risk of a catastrophic issue. Consider also that my Mazda 3 had a higher recommended lug torque than my Z4M. Surely no one expects a Mazda 3 to be driven harder than a Z4M.

https://www.machinedesign.com/archiv...astener-torque

If BBS doesn’t specify anything then I’d use the BMW number, but you could always reach out to them.

Last edited by chris719; 07-04-2022 at 03:55 PM..
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      07-04-2022, 05:07 PM   #36
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Quote:
Originally Posted by chris719 View Post
It’s got nothing to do with the wheel and tire combo or how you drive. It’s determined by required clamp load and bolt diameter.
So every bolt made in that same diameter would require 101?

Quote:
Originally Posted by chris719 View Post
If BBS doesn’t specify anything then I’d use the BMW number, but you could always reach out to them.
I think I'll do that, just to see what they say.
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      07-04-2022, 05:24 PM   #37
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Quote:
Originally Posted by ///MPhatic View Post
So every bolt made in that same diameter would require 101?

I think I'll do that, just to see what they say.
The clamp force would be decided on usually when choosing the fastener I think, so it's sort of implicit. Image taken from an earlier post. This is on the high end, not minimum.


Last edited by chris719; 07-04-2022 at 06:24 PM..
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      07-05-2022, 12:34 AM   #38
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Quote:
Originally Posted by ///MPhatic View Post
Well, you know I'll do what you tell me, I'm just being a bit cautious because I'm not sure my torque wrench is spot on, and I don't use BMW lugs, I use BBS 2-piece.




Yeah, respectfully I don't agree with that. Many things are tweakable taking usage into account. The 70 mph speed limit is for mini-vans and Ferrari's? I don't believe that for a second, and I certainly believe that if you're driving a car normally things are different than racing it, and BMW absolutely considered this car a weekend racer.

I'll use the 101, but I'd need hard data to support that it's better for a light wheel/tire combo with BBS lugs and no track days vs the stock heavy combo, stock lugs and the probability of track days.

Haha thanks for the flattery - but I don't know everything, I know stuff but not everything.

If the BBS wheels are designed to fit bmw's bolt pattern the torque will be fine. You also have to remember that the wheel hub area is designed to take immense forces from cornering loads and acceleration loads, 101 ft/lbs of torque is literally nothing to the wheel compared to pulling 1 G in a 3500 lbs car.


You could get your wrench recalibrated, but for things like wheel bolts you should be fine, the bolt diameter and material is so strong you don't really risk stripping it easily. The wheel itself should also be fine, and capable of taking more torque than the thread can actually handle.

Quote:
Originally Posted by chris719 View Post
It’s got nothing to do with the wheel and tire combo or how you drive. It’s determined by required clamp load and bolt diameter. BMW uses the same spec for this hardware on every car it’s used on. They changed the spec when they changed the bolts. There’s always margin so I’m guessing your wheels won’t fall off at 80, but you never explained what you hope to gain by undertightening them.

I understand what you mean when it comes some other specs where we understand the design intent well and have other goals, but I truly don’t see what less torque does here other than increase the risk of a catastrophic issue. Consider also that my Mazda 3 had a higher recommended lug torque than my Z4M. Surely no one expects a Mazda 3 to be driven harder than a Z4M.

https://www.machinedesign.com/archiv...astener-torque


If BBS doesn’t specify anything then I’d use the BMW number, but you could always reach out to them.
Exactly! The clamping load is critical to keep the fastener tight and help secure the bolt, you must stretch the bolt within its range of elastic deformation to load up the threads enough to hold the item securely without failing. If you do it too loose there is not enough load on the threads making it easier for the bolt to vibrate lose (along with other factors), and this is a really bad thing on a wheel.


Quote:
Originally Posted by ///MPhatic View Post
So every bolt made in that same diameter would require 101?



I think I'll do that, just to see what they say.

This is a general range, but it depends on material grade, size, thread pattern (coarse vs fine threads), female and male thread material (i.e. a harder metal going into a softer metal like a steel bolt going into aluminium) etc. Generally go with the engineering recommendation for your product - in this case bmw, and if you cannot find it then go with the general recommendations.


Quote:
Originally Posted by chris719 View Post
The clamp force would be decided on usually when choosing the fastener I think, so it's sort of implicit. Image taken from an earlier post. This is on the high end, not minimum.


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