5-point belt without cage? Options

[Keyser Sose]

Using a three-point harness what exactly happens when you're t-boned on the passenger side of the car or slide into something passenger side first? From that angle of impact what exactly is restraining you?

[SirAndy]

From that angle of impact what exactly is restraining you?

The lap belt ...
(IMG:style_emoticons/default/shades.gif)

[arne]

Mine will lock with a quick tug. If yours don't, something is wrong.

[Justinp71]

Mine will lock with a quick tug. If yours don't, something is wrong.

Thanks, my passenger side is the same way. I will look into that asap.

[Justinp71]

Have you guys noticed that the 914 inertia belts only work when you get on the brakes hard? But in a modern car they also work by pulling them very fast? Or do my 914 inertia belts need a rebuild?

Do you have the chrome bracket that redirects the belt so it still goes straight down from the reel?
If not, your belts will never work correctly.


Which is another reason why i prefer the non-retractable early style belts ...
(IMG:style_emoticons/default/smile.gif)

Yes, mounted to the inside of the b-pillar, correct?

[Keyser Sose]

From that angle of impact what exactly is restraining you?

The lap belt ...
(IMG:style_emoticons/default/shades.gif)

So in a passenger side collision a three-point harness is the functional equivalent of a lap belt? Is that really acceptable? It isn't to me.

[SirAndy]

So in a passenger side collision a three-point harness is the functional equivalent of a lap belt? Is that really acceptable? It isn't to me.

It's the same for every car you've ever driven. In fact, your 3-point won't do much beyond the lap belt in a driver side collision either.

Try yanking your top seat belt at an 90 degree angle right at the reel and see how well that works. They aren't designed for that unless you have some sort of bracket that redirects the pull of the belt.

And that's the same on any brand new car today as it is on a 914.
(IMG:style_emoticons/default/shades.gif)

[Keyser Sose]

So in a passenger side collision a three-point harness is the functional equivalent of a lap belt? Is that really acceptable? It isn't to me.

It's the same for every car you've ever driven. In fact, your 3-point won't do much beyond the lap belt in a driver side collision either.

Try yanking your top seat belt at an 90 degree angle right at the reel and see how well that works. They aren't designed for that unless you have some sort of bracket that redirects the pull of the belt.

And that's the same on any brand new car today as it is on a 914.
(IMG:style_emoticons/default/shades.gif)

Actually no, new cars today have air bags, 914's don't, and my 914 has 4-point belts. i've heard the negative opinions about four pointers on the street, and the convenience things Dave mentioned are certainly true, but there's no direct comparison I can think of where the performance in a collision of four point belts are inferior to three-pointer. Am I wrong about that? As you mentioned, in a passenger side collision the three-point harnesses are actually only lap belts... and lap belts were outlawed... when was it?

I know it's only opinion and I'm aware of the ongoing back and forth. It would be interesting to see some quantitative data, if it's available. Have you ever seen any?

[whitetwinturbo]

.............a grim reminder to watch everyone around you and be ready for evasive action. 914's are hard to see due to their tiny size.

Interestingly, my 1997 Porsche belts tighten when accelerating hard then loosen when the throttle is off.....

[jd74914]

Actually no, new cars today have air bags, 914's don't, and my 914 has 4-point belts. i've heard the negative opinions about four pointers on the street, and the convenience things Dave mentioned are certainly true, but there's no direct comparison I can think of where the performance in a collision of four point belts are inferior to three-pointer. Am I wrong about that? As you mentioned, in a passenger side collision the three-point harnesses are actually only lap belts... and lap belts were outlawed... when was it?

I know it's only opinion and I'm aware of the ongoing back and forth. It would be interesting to see some quantitative data, if it's available. Have you ever seen any?

4-points are considered dangerous since you can submarine and your body can shift forward under the belt in case of accident (unless using the sweet Schroth belts) unlike 3-point belts which grab you and keep you from pulling forwards. Wearing a cheap 4-point is almost like not wearing a belt in a forward collision. (IMG:style_emoticons/default/sad.gif)

If I have time later I'll try to find the Schroth documentation on 4-pts showing the above.

[falcor75]

https://www.schrothracing.com/technology

[Keyser Sose]

4-points are considered dangerous since you can submarine and your body can shift forward under the belt in case of accident (unless using the sweet Schroth belts) unlike 3-point belts which grab you and keep you from pulling forwards. Wearing a cheap 4-point is almost like not wearing a belt in a forward collision. (IMG:style_emoticons/default/sad.gif)

If I have time later I'll try to find the Schroth documentation on 4-pts showing the above.

I'd be curious to see that. The "ASM Anti Sub Marining Technology" section in that Schroth link just says it's "better" but doesn't explain how. They also limit their "safer" claims to frontal impacts only. I quite frankly can't see anything in a 914's three point harness that "grabs you" to keep you from pulling forwards, making it safer than any four-point, or anything at all in a three-point that restrains you if you're hit from either side. I've heard the anti-submarine claims before but have never seen substantiation, so I'm curious to see what that Schroth documentation has to say.

[jd74914]

There is a white paper on it that I'm not finding at the moment. For now here's a video:


https://www.youtube.com/watch?v=HR_FhuSEaU8


Basically, ASM uses straps of different "modulus" so one stretches more than the other causing you to get pulled somewhat similar to a 3 point harness so you get jammed by the lap belt vs. holding you evenly on both shoulders allowing you to slide. I'm not sure what the implications of this modification are in a side impact scenario.

[Keyser Sose]

I can see that. The different modulus of elasticity would let one shoulder travel further forward, making the body bend slightly around the lap belt, thus reducing the submarine effect. Interesting. Or you could accomplish the same thing by leaving the inside shoulder belt on your standard four-point harness slightly loose. Or upgrade to a five-point harness.

But this question wasn't about the different technologies used in four-point harnesses, it's the about the comparative safety of a standard three-point retractable harness compared to a four or five point. It was said that the three point harness is safer and the four-point harness is unsafe. I doubt both of those points in all cases, but especially in a side collision, and would love to see something empirical, either way.