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Last Post 12/17/2004 6:17 PM by  cwel
The airbag debate
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jeyping
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12/16/2004 2:23 PM
    I've been trying to gather some pros and cons on this issue: "e;Do airbags cause more harm than good in a frontal collision?"e; So all you out there with case studies, opinions, and facts please contribute, I'm really curious.

    Here's what I can see so far;

    Cons:
    - Airbags deploy. The airbag itself and the smoke obscure the vision of the driver, who might still need to be able to see and control the car to a stop after impact.
    - A very slight chance of death from the explosive nature of the airbag, though usually the case is the driver was sitting too close to the steering wheel.

    Pros:
    - The traditional answer, "e;The air bag prevents your face from hitting the steering wheel!"e; I just went to Progressive Insurance's website and looked at some 40 mph impact videos: http://www.progressive.com/RC/VSafe...videos.asp In every case, the dummy's face hit the airbag. But also in every case, it seems like there was a ton of slack in the seat belt! Isn't there supposed to be a tensioner that prevents that?


    I heard that in a frontal collision, if you are maintaining a proper distance from the steering wheel, you're not supposed to even come in contact with the airbag. Then what is the darn thing there for?

    I've been in a 25 mph frontal collision. The car did not have airbags. My face did not hit the steering wheel. The seat belt tensioners held on really well (even in a 15-year-old car).

    But I will accept the argument that had the impact been 50 mph, the forces would have been so great that I really would have hit my face - but I think I might have broken my neck too because it was definitely sore from "e;just"e; a 25 mph impact.
    DaveW
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    12/16/2004 2:31 PM
    IIRC, seat belts have a ton of stretch built into them...also, "e;restraint"e; is a system. So, a non airbag car may have less stretch in the belt at the expense of possible injury. An air bag vehicle would then have more stretch which would allow your body to slow down rather than abrupty stop.

    I didn't go to all of the safety seminars last year at the National Convention, but hearing from those who did, it appeared to be VERY informative.

    DaveW
    MattG
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    12/16/2004 3:02 PM
    My car has little to no stretch. If I hit the brakes hard it will tighten up and pin me back in the seat.

    Overall the issue is rapid deceleration. The airbag acts to slow deceleration.

    Remember:
    You don't die from Falls. You die from stops. or the damage caused from the stop.

    Your internal organs slosh around often causing the injury. Airbags help to limit the amount your brain sloshes around.
    DaveW
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    12/16/2004 3:19 PM
    [QUOTE]My car has little to no stretch. If I hit the brakes hard it will tighten up and pin me back in the seat.
    [/QUOTE]I'm no safety expert, but I'm guessing that you'd be lucky to see 1.0g on braking under the best conditions...but a small accident could easily go 10-15-20g's for a short time. I mean, I bet you could throw yourself backwards 100 times against an Integra seat and it would barely budge, but both seats collapsed in Carl and Jeef's accident.

    Anyway, its the slowing deceleration that matters (liek you said).

    DaveW
    vtluu
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    12/16/2004 3:23 PM
    [QUOTE]Originally posted by jeyping:
    The airbag itself and the smoke obscure the vision of the driver, who might still need to be able to see and control the car to a stop after impact.[/QUOTE]The latest airbag systems will only deploy if they absolutely need to. In such cases, the front end of the car is so badly damaged I doubt you'd have any control of the car anyway, so being able to see wouldn't really help.
    sburkett
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    12/16/2004 3:40 PM
    Useless trivia that has little relevance to the thread:

    The rate (or first derivative) of acceleration is technically called the "e;jerk"e;. I just like to say "e;jerk"e;. :D

    Back on topic: I like airbags except in racecars.

    Steven
    DaveW
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    12/16/2004 3:53 PM
    Hehe...he said Jerk :)

    DaveW
    Bryan S
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    12/16/2004 6:08 PM
    Another factor that this thread got me thinking about, seat belt degrdation. Remember the article in Sports car a year or so ago on seat belts? How the webbing looses about half of it's strength after just a few years. I can't imagine that street belts are made out of a webbing that is to much different, certinly not better than a racing belt. They have to deteriorate. So, just how good are the belts in a 12 year old car in an accident? yet you never see anything on replacement of belts.
    vtluu
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    12/16/2004 6:20 PM
    [QUOTE]Originally posted by Bryan Sechrist:
    Another factor that this thread got me thinking about, seat belt degrdation. Remember the article in Sports car a year or so ago on seat belts? How the webbing looses about half of it's strength after just a few years. I can't imagine that street belts are made out of a webbing that is to much different, certinly not better than a racing belt. They have to deteriorate. So, just how good are the belts in a 12 year old car in an accident? yet you never see anything on replacement of belts. [/QUOTE]That may not be true... Schroth makes a lot of hay about how their belts are polyester rather than nylon; the latter deteriorates in UV light hence the rather short life. I would imagine that street belts are made more for durability.
    ConeTrouble
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    12/17/2004 9:43 AM
    [QUOTE]Originally posted by vtluu:
    The latest airbag systems will only deploy if they absolutely need to. In such cases, the front end of the car is so badly damaged I doubt you'd have any control of the car anyway, so being able to see wouldn't really help.[/QUOTE]While this is nice for those of you driving shiny new cars, those of us out there who have some of the first iterations are not as lucky. My first autoxr was a '98 SVT Contour, and I hit a deer @ 80 mph or so. The airbag went off even though it was a glancing blow to the passenger side. I happened to be driving on a part of the freeway where there was road construction on one side, and a dropoff into a water-filled ditch on the other.

    I wish I could sit here and tell you that I had the wherewithal to be completely cognizant of those facts after the impact; alas, the impact of the bag to my head, the increadible amount of smoke, and the fact that the deer impact crumpled the front of the car and damaged the horn such that it was continually going off, all had their say in my disorientation. I was fortunate to bring the car to a stop there on the side of the freeway.


    In another instance, I was driving a '93 Ford Ranger and had a head-on with a Honda Accord at about 40 mph. The airbag never went off. The impact was hard enough that the cigarettes that were sticking up out of the ashtray were cleanly sheared off when the ashtray abruptly closed.


    I can't really say that I have ever had one go off when it should...
    rered02
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    12/17/2004 10:42 AM
    Originally posted by vtluu:
    [QUOTE] That may not be true... Schroth makes a lot of hay about how their belts are polyester rather than nylon; the latter deteriorates in UV light hence the rather short life. I would imagine that street belts are made more for durability. [/QUOTE]I had not paid any attention to that until you mentioned it here. I have had exactly the opposite experience with polyester versus nylon in dealing with lines (ropes) on boats. Many people use polyester line on small boats for anchor lines and winch ropes on trailers - they tend to deteriorate in the sun and water losing most of their strength, but without showing outward signs of that deterioration - hence they fail all at once, without warning. I use nylon lines instead, and have had much better service.

    I wonder why it is the opposite in Schroth's testing? Perhaps, like other things, there are many variations on composition - nylon does not necessarily equal nylon and so forth.

    Thanks for the info - I'll have to do more research - I'm curious now.
    vtluu
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    12/17/2004 11:05 AM
    http://www.schroth.com/english/prod...ebbing.htm

    [QUOTE] [IMG]http://www.schroth.com/produkte/images/images/produkte_technology/webbing_en.gif[/IMG]

    Webbing that makes the difference! The webbing we use is especially designed and manufactured for SCHROTH. Each lot manufactured must pass our stringent quality control procedures. SCHROTH only uses Polyester material. Polyester has advantages over Polyamide (NYLON®) webbing. Advantages, such as lesser degradation under light (see figure 1) and a resistance against acids like battery acid. In addition Polyester does not absorb moisture so the performance of SCHROTH harnesses do not change whatever the climate may be. Polyester also has a better force/elongation ratio so a well designed webbing can convert more energy during an accident. Unique to SCHROTH is the „memory effect“ we have designed into our webbing. Special mono filaments laterally woven in, perform like small leaf springs and keep the webbing flat. This results in better load spreading over the full width of the SCHROTH webbing. An additional advantage of the SCHROTH webbing: The special weaving technology forms round edges for additional comfort (see figure 2).[/QUOTE]
    rered02
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    12/17/2004 11:52 AM
    Sorry - I just realized that I was confusing Polyproplene with Polyester. Polyproplene is the stuff that breaks down so bad in the sun/water. My bad.
    vtluu
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    12/17/2004 12:24 PM
    It does give pause for thought though; even according to Schroth's (rather small) graph polyester webbing has less than 60% of its original strength after 2 years. So what's the implication for street cars? I.e., do they make OEM belts out of something even more indestructible (and if so, why wouldn't Schroth [i]et al[/i] use the same), or do OEM belts have the same deterioration--and what does this mean for a street car that's 10 or 20 years old?
    Lynn
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    12/17/2004 5:14 PM
    I think you are assuming far to much when you say the materials in stock belts are better than those used in racing belts. Car manufacturers won't spend an extra dime on anything unless forced to do so.
    vtluu
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    12/17/2004 5:20 PM
    [QUOTE]Originally posted by Lynn:
    I think you are assuming far to much when you say the materials in stock belts are better than those used in racing belts. Car manufacturers won't spend an extra dime on anything unless forced to do so. [/QUOTE]I'm not assuming at all, I asked if that was the case (and I'd follow the same line of reasoning as you have, with the same conclusion). (On the other hand, the risk of lawsuits and bad press would tend to keep manufacturers from skimping on safety equipment, maybe?)

    By that reasoning shouldn't we be replacing the seat belts in street cars every few years? And yet nobody does, so how do we explain this?

    Maybe (and I'm speculating here) the answer is racing and street (OEM) belts are fundamentally different? I.e. the former are designed to perform well for very high-energy accidents but not to last, and the latter for somewhat lower-energy impacts but to last many years?
    cwel
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    12/17/2004 6:17 PM
    SCHROTH Belts and Harness' have an "e;ENERGY CONVERSION DEVICE"e; (their nomenclature not mine) this is stitched loop designed to breakaway under high G-loading (High impact). This allows tight cinch down and break-a-away to lessen (i.e. smooth out impact load), activating the "e;ENERGY CONVERSION DEVICE"e; requires belt / harness replacement as the are not repairable.

    2004 SCHROTH Belts and Harness' are tagged valid thru 2008
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