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Old 03-25-2010, 07:07 PM   #21
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The windsheild will crush either way.
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Old 03-26-2010, 09:45 AM   #22
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It (roll bar) wasn't designed to keep the windshield in mint condition if you had a rollover.

Don't forget something, even a terrible rollover with a roll bar still has a solid structure supporting the car. The point isn't to keep the windscreen from crushing, its to keep YOU from crushing by supporting the mid/rear point of the car.



Even if the windscreen frame still collapsed during the crash I don't see the extra added bars doing any harm, but speculate it might add just a tiny bit of extra structure. However with that said I'm not an engineer so my speculation is worth basically nothing.
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Old 03-26-2010, 10:18 AM   #23
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the sphincter is connect to the...colon.
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Old 03-26-2010, 10:25 AM   #24
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Quote:
Originally Posted by hustler View Post
The windsheild will crush either way.
I've had this discussion with a friend of mine, who was looking for increased rigidity & safety while trying to avoid the full cage (he really like my bolt-in front cage section), and, while looking into center roofline bars, several people told him that the windshield WILL fold in during a rollover, most likely taking the roofline bars along with it.

Now, if you had installed bars along the windshield, running down into the floorboards, THAT WOULD be a slight improvement, which WILL keep the roofline bars from collapsing, but, the corners of the windshield will still fold in in a rollover, hurting the driver.
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Old 03-26-2010, 11:37 AM   #25
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Quote:
Originally Posted by alik View Post
Now, if you had installed bars along the windshield, running down into the floorboards, THAT WOULD be a slight improvement, which WILL keep the roofline bars from collapsing.
Agreed.

The weight is on the front in a rollover (motor). To me, it looks like that bar will act as leverage on the mounting points and pull the bar towards the driver or maybe tear out the bolts. 6 point or no roof bar.
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Old 03-26-2010, 11:48 AM   #26
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Quote:
Originally Posted by ARTech View Post
Agreed.

The weight is on the front in a rollover (motor). To me, it looks like that bar will act as leverage on the mounting points and pull the bar towards the driver or maybe tear out the bolts. 6 point or no roof bar.
+1

Do not want.

One more thing to hit your head on in a street car, for minimal benefit, and a track car is better off with a full cage.

Since it is a boxed off section it may hold up better, as the longitudinal bars would technically be in compression, and not see a bending moment until the A-pillars buckle. In reality buckling cannot be assumed to happen uniformly, and the front welds would like not hold.

Even if it stays together, when the windshield frame is compromised the bars may actually push back on the roll bar, making it more likely that the rear mounting points would puncture through the chassis.
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Old 03-26-2010, 11:53 AM   #27
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For street driving, you must have dual durometer padding on your rollbars. Not really necessary behind the seat, but, crucial for any metal bar that your noggin' might come in contact with.
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Old 03-26-2010, 12:31 PM   #28
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Originally Posted by elesjuan View Post



The niggin might not get crushed in that pic, but it has a decent chance of being in its non-crushed state about 100 yards up the road.
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Old 03-26-2010, 04:19 PM   #29
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Quote:
Originally Posted by Sparetire View Post
The niggin might not get crushed in that pic, but it has a decent chance of being in its non-crushed state about 100 yards up the road.
Most rollbars are designed to preserve your head by supporting the weight on the nose of the car, and the rollbar hoop.

If you dray a line from the front cross member to the top of the bar you get the idea. Every flipped Miata I've seen has looked exactly like that. No one is expecting the windshield frame to do anything.

EDIT: Tall people may not fare so well...
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Roll Bar Connected to Windsheild-crash_m2sport6edit.gif  
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Old 03-26-2010, 07:48 PM   #30
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Quote:
Originally Posted by gospeed81 View Post
Most rollbars are designed to preserve your head by supporting the weight on the nose of the car, and the rollbar hoop.

If you dray a line from the front cross member to the top of the bar you get the idea. Every flipped Miata I've seen has looked exactly like that. No one is expecting the windshield frame to do anything.

EDIT: Tall people may not fare so well...
That is what I'm afraid of when I get a roll bar, my head will still be on the ground, but it is better than crushed all the way to the body line i guess.
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Old 03-26-2010, 07:55 PM   #31
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Quote:
Originally Posted by AutoFreak57 View Post
That is what I'm afraid of when I get a roll bar, my head will still be on the ground, but it is better than crushed all the way to the body line i guess.
Roll bars aren't made so much to protect your head, or scalp. Even at 5'11'' I'd expect to get a concussion and abrasion from being thrown around by tangential force.

Roll bars protect your spine from compression, ergo they carry half the weight of the car instead of your weak, never-seen-a-gym, puny back.

You can fix scrapes, and live through several concussions and still be fully functional. Spinal injuries usually leave folks in wheelchairs.
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Old 03-28-2010, 09:41 PM   #32
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My question is: How likely are you to get sliced up by that windsheild? Contact with the ground is unlikely sure, but that windsheild is pointed right at your face. If you plant that sucker right into a tree stup it looks pretty easy to slide it right into your face or neck and off it goes. Yeesh.
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Old 03-28-2010, 09:58 PM   #33
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Didnt someone make a "bends only" kit for a roll cage in the NA?I cant seem to find it anymore
(G)
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