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Old 02-19-2008, 12:16 PM   #41
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Quote:
Originally Posted by mazda/nissan View Post
as already stated i would never be able to pull my head down in a rolling car anyways.
it's more like, pavement pushing down your head, pushing your body down, as opposed to 6pt where you can't get pushed out of the belt, and therefore --> pavement still pushing on your head, but neck getting 4" shorter when body doesn't move.

Depending on the pavement/head-pushing, it may not matter, hence the need for a rollbar
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Old 02-19-2008, 12:30 PM   #42
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Originally Posted by mazda/nissan View Post
if that were the case how would wheel studs work?
You're talking about totally different forces.
At dead stop at 60mph, you will have a kinetic energy of something like 27000 joule (aka. nm), thats 19900 lbf. (assuming you are around 165 pounds).

How much torque do tour car have?
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Old 02-19-2008, 03:46 PM   #43
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I run a 3" Simpson harness in a sparco seat with a nutstrap. Make sure and get the 6-point or you'll smash your nuts from time to time. I welded in a harness bar on my roll bar, because I'm ******* ganxter, and I'll cut your ***.
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Old 02-19-2008, 04:41 PM   #44
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Quote:
Originally Posted by Niklas View Post
You're talking about totally different forces.
At dead stop at 60mph, you will have a kinetic energy of something like 27000 joule (aka. nm), thats 19900 lbf. (assuming you are around 165 pounds).

How much torque do tour car have?
what i mean is that since bolts aren't supposed to support an amount of force in a horizontal direction (in the eyes of some members), then woudln't wheel studs be stressed horizontally under sudden acceleration/decleration to the point of shearing since they are not designed to withstand such forces? I'm not saying a bolt would not shear if pushed too hard horizontally, i am saying that savington has a misunderstanding of how a rod of metal works
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Old 02-19-2008, 06:19 PM   #45
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Anyone want to see why you should have a roll bar on your miata, racing or not? You wouldn't believe how easy it really is to roll a small short wheel base car.. I watched with my own eyes a Ford tempo get t-boned at an intersection low speed, like maybe 30mph clipped.. The tempo spun 180 degrees, hit a curb, then rolled onto its roof.

Say you're driving down the highway and swerve to miss a deer, lose control of the car on pavement a good hard sideways slide can flip a car. Run off the road to miss something in the road, same thing could happen from a sideways slide with enough momentum.

Here I offer a youtube video of an NA miata rollover test. This test shows what happens when a car tumbling lands on its side upset, then FALLS with NO momentum, ONLY GRAVITY onto its top. The A-Pillars crush and you can see a dummy arm is crushed by the top of the door.



This isn't a typical violent rollover from what I've seen.. Just a good example of what'd happen if your car went from sitting on its side, to sitting on its roof.
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Old 02-19-2008, 06:24 PM   #46
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cool vid. so where is your roll bar, lol
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Old 02-19-2008, 06:44 PM   #47
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Quote:
Originally Posted by mazda/nissan View Post
and do you really think i'd fair much better if my head was skidding across the pavement with a 3pt. vs 6pt.? as already stated i would never be able to pull my head down in a rolling car anyways. And don't worry about the cockpit brace, i don't have one
Yeah. With the 3-point, when the ground hits your head, your head moves as your body collapses inwards. With a 6-point, your head hits the ground, and you ******* die. This is not a difficult concept to grasp, and if you can't do it, mabye you shouldn't be tackling such a major part of your build without some professional assistance.

Quote:
Originally Posted by mazda/nissan View Post
would there be a safety difference between having a separate bolted harness bar and welding a horizontal bar onto my future roll bar?
So long as you have a rollbar in both instances, and as long as the harness bar is properly attached, there is virtually no difference.

As far as wheel studs vs. cockpit brace goes, think about the forces. All a wheel stud has to do is transfer a force; it transfers the force of the tire being pummeled upwards into the suspension and into the car. The cockpit brace isn't transferring any force anywhere; the car is rigid, and so the bolts end up taking all the strain. This is why a car's drivetrain can be very reliable when it's just driving around on the street, but suddenly destroy itself at a drag strip; suddenly, the forces aren't being simply passed along (into wheelspin).
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Old 02-19-2008, 07:55 PM   #48
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Quote:
Originally Posted by Savington View Post
Yeah. With the 3-point, when the ground hits your head, your head moves as your body collapses inwards. With a 6-point, your head hits the ground, and you ******* die. This is not a difficult concept to grasp, and if you can't do it, mabye you shouldn't be tackling such a major part of your build without some professional assistance.



So long as you have a rollbar in both instances, and as long as the harness bar is properly attached, there is virtually no difference.

As far as wheel studs vs. cockpit brace goes, think about the forces. All a wheel stud has to do is transfer a force; it transfers the force of the tire being pummeled upwards into the suspension and into the car. The cockpit brace isn't transferring any force anywhere; the car is rigid, and so the bolts end up taking all the strain. This is why a car's drivetrain can be very reliable when it's just driving around on the street, but suddenly destroy itself at a drag strip; suddenly, the forces aren't being simply passed along (into wheelspin).
well when you brake heavily the weight of the car shifts forward making the car "feel" heavier, this force is also coupled with the force of the deceleration because the brake pads are stopping the rotors which are stopping the wheel studs which are stopping the wheels stopping the car. So all the momentum is therefore transferred to pressure being applied horizontally on those studs I'll admit attaching harnesses to the rear brace is not a good idea, but i doubt it would be the bolts that failed you Thx for the info on the harness bar you's guys, i'll just weld a horizontal support onto my rollbar when i make one
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Old 02-19-2008, 08:37 PM   #49
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Does anyone know if there is a good harness solution for the Boss Frog double hoop? They told me to wrap the harness around the bottom bars, but they are at an angle and I think that would allow for movement.

I'd rather not have to get something welded on it, but I suppose if I have to I have to.
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Old 02-19-2008, 08:55 PM   #50
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aren't you allowed to wrap it around vertical bars for track use?
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Old 02-19-2008, 09:51 PM   #51
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Quote:
Originally Posted by mazda/nissan View Post
aren't you allowed to wrap it around vertical bars for track use?
From the NASA handbook:
Quote:
6. The shoulder harness shall be mounted behind the driver and above a line drawn
downward from the shoulder point at an angle of no more than twenty (20)
degrees with the horizontal.
7. The seat, seat holes, and attachments to the seat are not permissible “harness
guides” for compliance with the angle requirement. Only specific harness guide
bars, or parts of the chassis or the cage are allowed to be used for this purpose.
The guide bar, if used, should not present a sharp edge to the belt. It should
provide as much area of support as possible to distribute the load.
I've read that people trying to attach their harness like Bossfrog shows on their website (to the vertical) have not passed tech for Nasa. That might be at the disgression of the inspector. Either way, i won't attach them any way but with a dedicated harness bar.
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Old 02-20-2008, 05:19 AM   #52
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Quote:
Originally Posted by whaaamx5 View Post
cool vid. so where is your roll bar, lol
Still in raw stock at Boss Frog cause my bank account won't support it.

Thats the next purchase, trust me. Its always been VERY high on my list of priorities, but I drive the car like Never anyway.. Always broken or snowing around here.
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Old 03-17-2008, 01:06 AM   #53
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If you have a 4 point harness and roll bar, you are just like this kid. I mean, what is he going to do if he rolls that thing with his 4 point harness on?

edit: sorry if i revived an old thread for a retarded reason.
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Old 03-17-2008, 05:15 AM   #54
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Haha well I got a laugh out of it.

Pedal cars for kids that are worth as much as 1.6 FTW!!
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Old 03-17-2008, 01:14 PM   #55
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Quote:
Originally Posted by wes65 View Post
If you have a 4 point harness and NO roll bar
looks better
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