Quote:
Originally Posted by ///MPhatic
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.
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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:
Originally Posted by chris719
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
So every bolt made in that same diameter would require 101?
I think I'll do that, just to see what they say.
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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:
Originally Posted by chris719
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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+1