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Could someone please explain to me why it is ok to use a 3 point belt but not a 4 point belt? I'm not seeing why the 4 point would be any worse?
Thanks,
Russ
 

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Could someone please explain to me why it is ok to use a 3 point belt but not a 4 point belt? I'm not seeing why the 4 point would be any worse?
Thanks,
Russ
The 4 point doesn't have a belt across the hips (lap belt) or between the legs , so in a forward impact, the occupant can be slung down and forward or up and forward.
 

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Could someone please explain to me why it is ok to use a 3 point belt but not a 4 point belt? I'm not seeing why the 4 point would be any worse?
Thanks,
Russ
It was explained to me that at the moment of impact your body is thrown forward, causing the shoulder straps to pull the lap belt upwards allowing your lower torso to "submarine" under the belt. Is that the correct reason? I don't know but it seems to make sense.
 

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I was about to say it sure looks to me like they have a lap belt, but I am just an idiot.

So it sounds like it is because of where the shoulder belts attach that is the problem?

I was planning on using the Schroth Racing 4 point harness with their asm technology. Any thoughts on their stuff?

Thanks,
Russ
 

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It was explained to me that at the moment of impact your body is thrown forward, causing the shoulder straps to pull the lap belt upwards allowing your lower torso to "submarine" under the belt. Is that the correct reason? I don't know but it seems to make sense.
Yup, that's basically it. The lap belt has to push on the only safe "hard point" in the area, your hip bone. When it's pulled up by the tension your torso puts on the shoulder belts, the lap belt is pulled above your hips and into your stomach, doing major soft tissue and organ damage. Russ, the Schroth do seem to be a safe hybrid, acting like something between a 4-point and 3-point by giving one shoulder strap "controlled stretch". IMO they are safe, just pay close attention to their installation instructions, especially the shoulder belt mounting locations. The primary job of the Sub belts are to keep the lap belt pulled down on the hips.
 

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Brakes are #1 rear disks not so much. I went with the led brake lights a major improvement everything else as need or budget will allow.
 

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Brake upgrades, especially the "jelly jar" single-pot master cylinder to a Dual Reservoir master cylinder are the best safety investment.
I experienced a sudden failure of one back in the late 70's and was lucky not to wreck as I unintentionally went thru a red light making a left turn on the way to high school.
Scared the [email protected] out of me at the time...😵
 

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@AllenHopp I thought about this one but he's working on a 1970 car that came from the factory with a dual Reservoir master cylinder
 

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Discussion Starter #111
@AllenHopp I thought about this one but he's working on a 1970 car that came from the factory with a dual Reservoir master cylinder
Wow surprised you knew. I didn’t even know that it came factory with it but I it was there when I bought it. It’s off now though along with the rest of the car.

That’s another question. Can I reuse the old master cylinder or is it best to buy a brand new one?
 

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That’s another question. Can I reuse the old master cylinder or is it best to buy a brand new one?
If I were you, I would put in an entirely new mc, stainless lines, new calipers, rear wheel cylinders and new braided stainless hoses. If you replace every part with new, consider synthetic silicone brake fluid and it will be hydrophobic and will not likely ever corrode, will not harm paint, has a higher boiling point, etc. unlike standard DOT 3 and 4 conventional fluid. You'll be surprised how well it stops, even if you use conventional. Just remember the two are not compatible, so new components are a must if converting.
 

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Discussion Starter #113
If I were you, I would put in an entirely new mc, stainless lines, new calipers, rear wheel cylinders and new braided stainless hoses. If you replace every part with new, consider synthetic silicone brake fluid and it will be hydrophobic and will not likely ever corrode, will not harm paint, has a higher boiling point, etc. unlike standard DOT 3 and 4 conventional fluid. You'll be surprised how well it stops, even if you use conventional. Just remember the two are not compatible, so new components are a must if converting.
Ok got it. I would prefer to do it the right way and replacing 49 year old parts seems like a good idea. Thanks for the information!
 

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6 pages and not one mention of selling the old car and buying a Volvo.
They're nice, too.
My best friend's mom had one in the 80s, we tried to kill it and it's still on the road in our old home town.
 

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If I were you, I would put in an entirely new mc, stainless lines, new calipers, rear wheel cylinders and new braided stainless hoses. If you replace every part with new, consider synthetic silicone brake fluid and it will be hydrophobic and will not likely ever corrode, will not harm paint, has a higher boiling point, etc. unlike standard DOT 3 and 4 conventional fluid. You'll be surprised how well it stops, even if you use conventional. Just remember the two are not compatible, so new components are a must if converting.
Yes to everything except the brake fluid. If you intend to track the car, use only DOT 4 race fluid. Motul 600, 660 or Castrol SRF are good options. Brakes are one item you DO NOT want to cheap out on! You want the fluid with the highest “wet” boiling point. I run the SRF.


Mark
 

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The 4 point doesn't have a belt across the hips (lap belt) or between the legs , so in a forward impact, the occupant can be slung down and forward or up and forward.
Just for clarification, 4 point belts do have a lap belt across the hips, but as others have said it can be pulled above the hips by the shoulder belts during impact.
 

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Could someone please explain to me why it is ok to use a 3 point belt but not a 4 point belt? I'm not seeing why the 4 point would be any worse?
Thanks,
Russ
Another point not mentioned is that restraining the shoulders without restraining the head is a bad idea. If the head goes forward without the shoulders all the stress is absorbed in the neck. One should use a HANS device with a 5 (4) belt system.
 

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Well, drying around on the street with a helmet/HANS is a bit beyond the scope of this discussion :) The Scroth ASM will be fine without a HANS, as far as a standard 5-point harness on the street without it, I don't think anyone knows if that is more or less safe than a 3-point, there's just no data.
 
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