ND Roll Bar!

"G_Body_Man: Sponsored by the number 3" (gbodyman) 07/14/2016 at 14:21 • Filed to: None

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!!!error: Indecipherable SUB-paragraph formatting!!! has exactly what the doctor ordered. Yay!

For Sweden > G_Body_Man: Sponsored by the number 3 07/14/2016 at 14:28

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Bolts

Why

G_Body_Man: Sponsored by the number 3 > For Sweden 07/14/2016 at 14:31

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No idea.

RamblinRover Luxury-Yacht > For Sweden 07/14/2016 at 14:34

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Because actually qualifying for restrictive safety specs is haaarddd.

d15b > For Sweden 07/14/2016 at 14:36

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Not exactly the most inspiring of designs.

dogisbadob > G_Body_Man: Sponsored by the number 3 07/14/2016 at 14:36

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hehehe Cusco

they’re known for their cosmetic “roll cages” :p

G_Body_Man: Sponsored by the number 3 > RamblinRover Luxury-Yacht 07/14/2016 at 14:49

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It has to be grade 10 metric hardware, right? I mean, it’s a roll bar put out by an established company. It seems very odd in design, but they must have run computer aided tests before putting it on the market, right?

RamblinRover Luxury-Yacht > G_Body_Man: Sponsored by the number 3 07/14/2016 at 14:54

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Possibly. A well-designed and correctly installed bolt interface can have a lot of advantages in installation and isn’t necessarily worse than a normalized welded join - BUT - it’s still not okay by a lot of classifying rules for roll bars. And here’s the thing - if they didn’t care about making it possible to adhere to the standards, the efficacy in general can be in doubt. There are a lot of iffy bars and cages out there, and many others that have been installed badly with the aid of incorrect bolting. It is what it is.

As a secondary note, it’s not even about the hardware used. It’s about the ability of the clamping force that hardware is applying to properly resist shear force by creating friction between the two faces. Very often if it’s not tightened properly, such an interface can fail all at once, when that friction is exceeded. With anything but a driveshaft, if you come through to serious shear loads directly on the shaft of the bolt and the flange hole it’s in, you may well have already lost - with a non-heat-treated flange, the bolt’s grade doesn’t matter for shear so much because it’s not the weak link. The only meaningful effect of the grade is the clamping force.

Stapleface > For Sweden 07/14/2016 at 15:02

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Maybe the bolts so you can take the crossbar off so the top can fit better? I dunno, just trying to make sense of this.

RamblinRover Luxury-Yacht > G_Body_Man: Sponsored by the number 3 07/14/2016 at 15:05

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Ask yourself this: what is the maximum shear strength of the coating on the bar? That coating is actually the point of least resistance at the friction interface between the bolted flanges. If it’s anodizing, then it may be okay... though only if it’s hideously tight and sort of galds together. If it’s powdercoat, then it comes down in an accident to “what is the shear strength of an engineered plastic?”. Not so good.

For Sweden > Stapleface 07/14/2016 at 15:08

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I hope those bolts are highly rated for shear strengh

RamblinRover Luxury-Yacht > For Sweden 07/14/2016 at 15:13

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My worry is actually about the coating. Sure, the flanges are big enough the bolts probably won’t rip out (sufficient bolt diameters clear aroung the holes), but under any kind of actual shear I don’t know what kind of friction the coating will sustain - and all the clamping force in the world can’t make paint stronger. Then it *would* be down to the bolt and flange hole shear.