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Old 01-19-2015, 10:50 PM   #41
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It will, though...
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Old 01-19-2015, 11:19 PM   #42
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Just ran a sim on 4 point bar traditional style with a main hoop using 1.5OD and 0.12 wall with 75ksi yield strength(TuffDOM) regular DOM 1020 steel is about 60ksi. using same 3000lb loads I got this.





not any stronger but about 10lb lighter due to superior strength compared to 35ksi I used for no brand bar.
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Old 01-19-2015, 11:21 PM   #43
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You are the dumbest dumb if you think you're doing these tests correctly, or that your bar is in any ways adding safety.
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Old 01-19-2015, 11:24 PM   #44
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Who makes a bar that looks like that anyways?
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Old 01-19-2015, 11:24 PM   #45
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Quote:
Originally Posted by concealer404 View Post
It will, though...
Show me a proof using statics/mechanics of materials or FEA analysis.
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Old 01-19-2015, 11:31 PM   #46
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Quote:
Originally Posted by Artsvetkov View Post
Show me a proof using statics/mechanics of materials or FEA analysis.
Show me real life proof that any of your statics/mechanics of materials or FEA analysis has anything to do with real life/actual roll over.

You still haven't come CLOSE to matching an actual roll bar or it's mounting points. Much less come close to real life forces.

If you're so hell bent on using FEA, you need to be doing stress tests on rolled over miata roll bars, not guessing by the weight of the miata.
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Old 01-19-2015, 11:36 PM   #47
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Originally Posted by Artsvetkov View Post
Show me a proof using statics/mechanics of materials or FEA analysis.
How about i don't need to. I took advantage of chep legit miata parts and spent my time working a few hours of overtime to buy a quality part that isn't dangerous.

If your idea was good, people would have done it. No certified roll bars look like that. Either of your examples, actually.
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Old 01-19-2015, 11:58 PM   #48
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Hard Dog Hard Bar Sport - Polished Stainless Steel

That's what I used for second bar. I used same loads for comparative analysis only.

Anything I say or prove doesn't matter because everyone is going on "Nobody does this bias".
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Old 01-20-2015, 12:15 AM   #49
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I would be more worried about the material than the structure of the bar. Is it really 1/8 inch thick tubing? Because if so that is a damn thick style bar. Most of the ones I've seen are built out of like exhaust tubing.
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Old 01-20-2015, 12:17 AM   #50
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I think what everybody is trying to say is, if you take a buffer and some wax to a turd, no matter how much you polish it, its still a piece of ****.
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Old 01-20-2015, 12:20 AM   #51
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I have no idea where this bar came from, but I was surprised at how thick the components on it are, I would of expected exhaust tubing as well. It weights over 30lb which is consistent with mass properties of my model.
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Old 01-20-2015, 01:18 AM   #52
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I think I found the source of this style bar MossMiata.com - Parts & Accessories for Your Mazda Miata

The ones I saw on eBay are polished stainless steel and 2" OD, mine is chrome finish with 2.25" OD. Maybe that's why ebay bars are so thin, because they are a visual copy of this one but they are too cheap to add chrome plating process and knock it out of a thin walled stainless steel to save cost.
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Old 01-20-2015, 01:32 AM   #53
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You notice how even Moss lists it as a style bar?

C'mon man. You're smarter than that.

I mean there's really no need to pretend. Half the cars here don't even run any bar at all, which is dangerous too, so it's not like you're doing something absurdly crazy. I just think everyone's issue with this is that you're convincing yourself that this is safe when it's not.
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Old 01-20-2015, 01:43 AM   #54
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They not listing it because it needs to have 4 points of contact. I get what you are saying, if I was to race this car I would go with 8 or 10 point cage, but for street use I don't think it's worse than nothing. I agree that with 2 points of contact it is worse than nothing.
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Old 01-20-2015, 08:13 AM   #55
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The sanctioning bodies for NASA and SCCA track days also require a minimum of one diagonal support to the main hoop and that your helmeted head not exist at a higher point than a line drawn from the top of the rollbar to the top of the windshield (infamous broomstick test).
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Old 01-20-2015, 02:14 PM   #56
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build it like this. then run your tests the material should be 1.75" .095 Dom tubing.
FYI this is a lemons cage. it doesn't get any "less" then this.



here is a typical NASA legal roll bar. note the support tube mounting position on the main hoop. also note the cross bar location inside the main hoop.


although there is some name calling in this thread. everyone does have your safety in mind, and they are trying to help you.
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Z3 1990 Miata-lemons-ascendant-inline-cage-match.jpg  

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Old 01-21-2015, 12:38 AM   #57
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I will give that sim a shot, not trying to prove that I have awesome bar or anything, I'm just curious how will a proper sanctioned bar will behave under equivalent loads and sort of stress distribution path it will take and see FOS.
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Old 01-21-2015, 10:55 AM   #58
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Quote:
Originally Posted by Artsvetkov View Post
I will give that sim a shot, not trying to prove that I have awesome bar or anything, I'm just curious how will a proper sanctioned bar will behave under equivalent loads and sort of stress distribution path it will take and see FOS.
a properly sized bar will attempt to protect you in a roll over. the style bars in the industry have no horizontal support. when a car rolls over, the forces are not 100% vertical. The vehicle will be moving forwards or backwards too. that forward movement will bend the style bar and it could trap you under it. that's why everyone is calling it a mouse trap.

the other thing to look at is that the style bar simply isn't tall enough to protect you in a roll over. that combined with the potential to be trapped by it makes running no style bar safer then running one.
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Old 01-21-2015, 12:48 PM   #59
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The other thing that no one has really pointed out is how the "style bar" bolts to where the seatbelt bolt in. For a roll bar that is not an acceptable mounting point. If you check out how any of the real roll bars mount, they may have a bolt there, but they also go much further down and bolt into the actual chassis.
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Old 10-18-2015, 11:51 AM   #60
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Done and sold.









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