Anti-sub mounting

[Darren]

Many 6-point harness installations that people have run with in the past, especially before racing seats were mandatory, were not exactly correct.  I've been obsessing over harness installations for a few years now, so curious to hear others' thoughts.

In many cases in the past, the anti-sub strap, in a 6-point setup, was mounted to the front seat mounting bolts, totally defeating the purpose.  A main function of the anti-sub strap is to keep the lap belt in place.  With the straps mounted to the front of the seat, it served to mostly pull the lap belt away from the person's hips -- very bad.

In a 5-point harness, the single anti-sub strap mainly just keeps the lap belt in place.  I sure hope it doesn't keep me from submarining below the belts, I have some sensitive goods right there.  Keeping the lap belt in place should stop the person from submarining though, and hopefully before the 5th point starts taking load.

In a 6-point harness is where I think there is more of a debate and more variation in the installation.  I've talked to several manufacturers who have told me that the proper way to install a 6-point harness is so that you actually sit on it.  The 6-point harness offers an advantage that you can't get with a 5-point, in that it prevents your hips from rotating under the lap belt.  Installed properly, with the anti-sub strap installed behind the person, the 5th/6th points will loop from under the person's leg and sort of cup their hips into the seat.

And this is where I have a question -- in most cases the manufacturers seem to advocate attaching the 5th/6th points to the same mounting location as the lap belts.  This of course creates a situation where a failure on one mounting location could cause 2 of the 6 points to fail.  Is it considered acceptible under our rules/guidelines to have the 6 point anti-sub strap mounted to the lap belt points? Or does it have to be to seperate points, i.e. 2 eyelets in the tunnel?  Where are people mounting their 5th/6th points?

The best of both worlds is of course the 7-point harness (though I've never seen one) that has 3 anti-sub straps, the 5th point from the 5 point and the 5th/6th from the 6 point.  This will properly locate the lap belt and keep your hips from rotating.

I'm curious to hear anyone elses' thoughts.

[TwentySix]

Check out these threads on Rennlist... HTH

http://forums.rennlist.com/rennforums/sh...ss+install

http://forums.rennlist.com/rennforums/sh...ss+install

[Phokaioglaukos]

Also read this manual from Schroth. It's excellent and has application beyond Schroth's products: http://www.schrothracing.com/docs/Compet...ctions.pdf

Pay particular attention tothe angles and lengths of harnesses if you use a HANS, and I and many others do. No point in having one if you don't set the harnesses properly to work.

For sub belts I use the B-K sub belt bar on my GT3 seats. That is NOT legal for Porsche club racing--they require that the sub belts be attached to the floor of the car, not the seat. In the ROW Porsche sells the GT3 seats in my car with Schroth harnesses attached to the seats....

[Darren]

Thanks for the links.  I've read several of these manuals and have come to the conclusion that most 6-point installations that I've seen, DE or racing, involve some sort of compromise.  I can't see how you can create the correct angle on the 6-point setup without modifying the seat.

In the cars I've been working on recently, I've installed aluminum seats because they are easier to modify and I don't have to worry as much about affecting the integrety of the seat when I cut holes.  I certainly wouldn't want to cut sub strap holes in an FIA certified fiberglass seat.

[Phokaioglaukos]

Darren wrote:

I can't see how you can create the correct angle on the 6-point setup without modifying the seat.

Look for my car and observe how the B-K bar works with the seat and rollbar. It took a bit of measuring, but it works well.

Note that the angle one needs for shoulder belts with a HANS is precise. I have the driver seat set for me and adjusted the shoulder belts on the rollbar to get the right angle. A taller driver would need the seat back further, so to get the right belt angle the attachment of the shoulder belts to the rollbar would need to change. That's why I have installed belt keepers that can be moved on the rollbar. I don't make that adjustment often, but I could. For the passenger seat I have set the shoulder belts properly for the seat in the full back position so that my passenger will have the right angle on the shoulder belts. I chose the Schroth Hybrid II HANS for my belts but the non-HANS version for the passenger (which works with HANS too).

[Darren]

I have the GT3 seats and BK bar in my 996.  The setup isn't ideal because the 6-point is attached to that bar and passing through the seat sub-strap hole and so it is basically functioning as a 5-point.  But I'm not cutting the seat.

Is that how yours are installed also Chris?

[Phokaioglaukos]

Darren, that is how mine are installed, but I'm not sure what you mean that the sub belts are working line a 5-point. Do you mean the two sub straps are so close together that they feel like one belt in the middle?

[Darren]

Phokaioglaukos wrote:

Darren, that is how mine are installed, but I'm not sure what you mean that the sub belts are working line a 5-point. Do you mean the two sub straps are so close together that they feel like one belt in the middle?

Yes, exactly. The purpose of the split subs is really to prevent the driver's hips from rotating in the case of an accident. They are too close together, and also mounted too far forward. To function as a proper 6-point, from what I've read and been told, the sub straps should be mounted behind the driver's spine, go through the seat, and wrap up around the thighs. This effectively cups the driver's hips. It wouldn't be sufficient in our case to mount the belts further towards the rear of the car because then the load would be on the seat itself.

[Phokaioglaukos]

Darren wrote:

They are too close together, and also mounted too far forward.

I'm not with you on that. Look at this diagram from Schroth.

[Darren]

Yes, exactly, so that diagram shows the anti-sub belt mounted 0-20 degrees behind the chest plane.

On page 27 it says:

"Anti-submarining strap routing shall be vertical down from the groin, preferably approximately 20° back.

Anchor points shall be approximately 100 mm [4�?] lateral apart from each other. In case of a a low seating position (e.g. in open wheel race cars), this separation may be reduced since the anchor points are closer to the thighs."

So this is saying that 0' how we have them is ok, but mounting back farther is better.  Also about the 100mm spacing, my 2 sub straps are right next to each other, no gap whatsoever on the bar.  Attached this way, what possible benefit could 2 straps have over 1?  The straps for the 6-point should be far enough apart to get the desired cradling effect.

Reading from the manuals is great, but there may be slight model specific differences.  The Profi 6-point seems to have a larger T bar for the sub straps than mine do.  Notice, also on page 27, they give a description of installing the subs so that they pass through the back of the seat and you sit on them.

As a final point, they have a big warning box that reads:[size=1]

[size=2]Never use the SCHROTH Racing Harness unless the racing seat is designed with anti-submarining holes. Never run the anti-submarining straps over the front edge of a factory seat down to the floor. Such routing does not provide the desired anti-submarining effect, and in fact encourages submarining, which can cause severe injury and death.

[/size][/size]