6 point belt crotch straps

[Walt Fricke]

Replaced my 5 point (outdated) harness with a 6 point. It seems like the two crotch straps are going to press their edges sideways against my inner thighs. Anyone felt this?

I've got the center lock about an inch or two below my navel, which looks to put the lap belting in the nice single plane you want.

If I move it up to the navel, might this relieve the pressing? This is a Sabelt, with a sort of steel Y on the lock, so it stays attached to the crotch straps, which thus start out a couple of inches apart.

The sub strap mounts are placed at the specified 20 degree angle behind the slot in the seat. I kind of estimated where the new anchors should go side to side so the pull on the slots in the lock would be straight to the anchors, +/- the limitations imposed by the slot in the seat.

[stownsen914]

Walt - I have (had? can't recall now) an older Sabelt with the Y style dual sub strap attachment in my 914, and experienced the same thing. I also run the cam lock a little below the navel. I find it annoying mostly while buckling up, and never notice it while driving, for whatever that's worth.

[Walt Fricke]

I'm for the never notice part, I hope.

That's what everyone said about the HANS. For the MarkI with fixed tethers, that wasn't quite true - you noticed it when you were trying to turn your head to see cars in blind spots and such. I had to remount the right side mirror on my GT car. But with the sliding tether, you don't notice.

Thanks

[burgermeister]

I have the same setup (Takata belts, made by Schroth) on my track car, about the same position for the buckle. I also don't notice while driving, though it does feel weird in the garage.

[Walt Fricke]

I ended up using a zip tie around both a bit above the seat slot to get them in more of a fore and aft orientation. If I have a wreck hard enough to break the tie so the sub effectively becomes longer, I'm probably in trouble anyway.

So now I don't notice in the garage, on the grid, or on the track. I do like the 2" belts, though - easier on the HANS, and feel fine around the pelvis.

[burgermeister]

2" lap belts are considerably safer than the 3" versions to boot. They are less likely to slip over the pelvis and mangle your innards.

[Locker537]

The sub straps on my Schroth harness tend to turn themselves, so the flat sides are against my thighs. It's more comfortable than I would expect.

[stownsen914]

Originally Posted by burgermeister

2" lap belts are considerably safer than the 3" versions to boot. They are less likely to slip over the pelvis and mangle your innards.

I'd never heard this. I actually would've expected the 3" lap belt to spread loads over a wider area. Has it been demonstrated in crash testing that the 2" is better?

[Walt Fricke]

Yes - sled testing by Schroth maybe over 10 years or more ago showed that the 2" lap belts held the hips better. The HANS does all the spreading needed for the shoulder belts, and the 2" belt stays put better, or at least seems to do so. The minimum tensile strength required by the test organizations did not change, I believe, so the narrower belts meet those specs. The certification organizations have changed their standards for belt width accordingly. For track organizations you may see something like "2" only with a HANS," though almost all racing organizations just require the HANS (one or more vintage organizations don't).

I was fine with my 3"ers, but the new 2s are, if anything better once I dealt with the sub strap. I like mine, and wouldn't go back (though I wouldn't change an in spec belt just to go to 2"ers).

[burgermeister]

Our region (RSR) was lucky to have John Melvin (https://en.wikipedia.org/wiki/John_Melvin_(engineer)) as a member until his passing. He did research on automobile safety both on road and on track (NASCAR). That's where I heard that the 2" lap belt is safer.

John also was of the opinion that a 6 point harness was much better than a 5 point. He preferred the "formula car" method of mounting the belt when feasible (driver sits on the sub belts, they exit at the rear corners between the seat and back cushions and are then secured appropriately). Unfortunately most (all?) shell seats don't allow this. He told me that a 5 point first breaks your balls, and then breaks your back... though I personally imagine it depends on the angle of the driver's upper body, and in the typically upright 911 seating position a 5 point may work just fine. Alas, he seemed like a smart guy who knew what he was talking about, and I only use 6 point belts...