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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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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07-03-2022, 05:19 PM | #28 |
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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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07-03-2022, 09:44 PM | #30 | |
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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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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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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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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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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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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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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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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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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:
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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:
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03-31-2024, 03:23 PM | #39 |
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One reason is to have the lug nuts torqued at the same value so that you do not warp your rotors. Another one would be if there is insufficient torque on the bolts you could lose a tire and wheel. Having said that, this might not apply to the 2 piece rotors that I have on my car.
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04-01-2024, 02:18 AM | #40 |
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BMWs torque specs are, and always have been, the following:
M12 = 120 Nm +/- 10 Nm M14 = 140 Nm +/- 10 Nm https://www.newtis.info/tisv2/a/en/e...unting/5Tp9xUw On the newer cars with M14 they have removed the +/- 10 Nm though, F87: https://www.newtis.info/tisv2/a/en/f...els/1VnXy9B75W The same goes for M12 from E9X: https://www.newtis.info/tisv2/a/en/e...wheels/5HLATDw So the conclusion is that if you stay with 120 Nm for M12 and 140 Nm for M14 you'll be just fine.
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05-12-2024, 06:38 PM | #41 |
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This thread is kinda scary. If there is one fastener to torque properly it would be the wheel lugs (at least for the basic user-serviceable stuff). An improperly torqued fastener is already half broken. This is not a speed limit or a nanny-state regulation, it is metallurgy. Proper torque is determined by the bolt, so those with 2 piece bolts or studs need to check with those manufacturers. Too loose and the bolt flexes repeatedly until it fatigues and cracks; too tight and it is stretched past elastic and looses strength, then it fatigues and cracks.
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