Harnesses That Pass NASA HPDE Tech

[Rich H]

It sounds like that concession was made for the Schroth harnesses fitted with their ASM (anti-submarining technology). There is a little info about it here on the Schroth site.

According to another website, ASM incorporates "an extra flap of material sewn into the inboard shoulder belt that prevents you from sliding underneath the lap belt. In a 4 point harness made by some other company, the two shoulder straps restrain your upper body equally. They keep your chest from moving forward. However, this also pulls up on the lap belt and allows your accellerating pelvis to slide under the lap belt and cause serious damage to your stomach and intestines. With ASM, one of the shoulder belts will elongate at a different rate which will force your pelvis down into the seat cushion. Upon rebound, you will be placed back in an upright position with the belt correctly placed over your body."

I have a pair of these belts in my Westfield, and although I can't confirm that they work as advertised, they are a lot more comfortable than my old Sabelts (Schroth's webbing is softer and far more pliable).

-John

That's correct. Larry Marsala said that the ASM system is acceptable, and showed me a harness using it that he had on hand for illustration. That does not say, however, that NASA endorses this system or suggests buying it. Its just the only four-point option that's currently HPDE-acceptable. As I said earlier, anyone who disagrees shouldn't hesitate to take it up with NASA.

[JohnCh]

It sounds like that concession was made for the Schroth harnesses fitted with their ASM (anti-submarining technology). There is a little info about it here on the Schroth site.

According to another website, ASM incorporates "an extra flap of material sewn into the inboard shoulder belt that prevents you from sliding underneath the lap belt. In a 4 point harness made by some other company, the two shoulder straps restrain your upper body equally. They keep your chest from moving forward. However, this also pulls up on the lap belt and allows your accellerating pelvis to slide under the lap belt and cause serious damage to your stomach and intestines. With ASM, one of the shoulder belts will elongate at a different rate which will force your pelvis down into the seat cushion. Upon rebound, you will be placed back in an upright position with the belt correctly placed over your body."

I have a pair of these belts in my Westfield, and although I can't confirm that they work as advertised, they are a lot more comfortable than my old Sabelts (Schroth's webbing is softer and far more pliable).

-John

[slomove]

I
2. Four-point harnesses are prohibited, unless they incorporate a special impact release device on one of the shoulder straps so that the four-point harness behaves like a three-point harness in a frontal impact. In other words, the release device must allow the upper body to twist enough upon impact to prevent the body from submarining out of the bottom of the lap belt.

Now that sounds really dangerous... the remaining shoulder strap of a mutilated 4-point does not even go completely diagonal across the body (like a 3-point), still pulls up the hip belt and may just slip off the shoulder. It concerns me that they make such an a concession.

Gert

[Rich H]

I spoke with NASA NorCal Chief Scrutineer Larry Marsala, today at Infineon, to clarify NASA's rules regarding HPDE harnesses in sevens. Here's what he said.

1. A three-point DOT-style belt/harness, with no other belts installed in the car, will automatically pass HPDE tech in any car, so long as it is affixed to the car manufacturer's mounting points. Larry believes that such harnesses typically have a DOT label affixed, but they are acceptable without one.

2. Four-point harnesses are prohibited, unless they incorporate a special impact release device on one of the shoulder straps so that the four-point harness behaves like a three-point harness in a frontal impact. In other words, the release device must allow the upper body to twist enough upon impact to prevent the body from submarining out of the bottom of the lap belt.

3. Five-point, or more, harnesses will automatically pass HPDE tech if they are affixed to the car manufacturer's mounting points.

4. Anything else must comply with the Racing CC&Rs.

These requirements are the same as those that apply to all other cars, so sevens are not disadvantaged per se. Confusion arises, however, because some Caterhams, and perhaps other brands that I am not familiar with in detail, come factory-equipped with four-point harnesses. Some may also disagree with NASA's implication that a four-point harness is less safe than a three-point, and they may wish to take that up with Larry and/or CEO Jerry Kunzman.

Larry also strongly urges arm restraints in HPDE sevens, but NASA does not require this.

The obvious disclaimer here is that Larry represents NASA NorCal, and an inspector in a different NASA region might interpret differently. I would expect, however, that Jerry Kunzman will probably seek Larry's advice on responding to a question that comes from another region.

Hope this helps.

Rich H.