five-point harness sub belt placement?

Formerly Steve Wilkinson · 03-08-2002, 05:00 AM

Putting in my new Simpsons so my daughter can go to her first DE, and I have a question: Some of the advice I've seen here and there says the ringbolt for the submarine belt should be well aft, like under about where your butt sits. (My harnesses' sub belts are nowhere near long enough to allow that.) The Simpson instructions say it should be "aft of the chest line," whatever that means. The generic illustrations in the Simpson instruction sheet show it directly under the very forwardmost edge of the seat, and I haven't the faintes idea what kind of "chest line" that's aft of. In my aerobatic aircraft, the sub belt for its five points were about two inches aft of the front edge of the seats, which is where I'm planning to put them, for a variety of reasons, in the 911.

Is a DE tech inspector likely to have a problem with that?

Stephan

304065 · 03-08-2002, 06:13 AM

Don't know about the inspectors in Hudson Valley but my 6 point and 5-1/2 point (y-style, from the seat mounting points to a single center strap) harnesses, which were mounted to the forward seat mounting points, has been deemed acceptable by Metro NY and NNJR. My race car has it about 3 inches aft of the forward edge of the seat, and she's been certified by PCA club racing and HSR. So I would never speak for the local scrutineers, but if you do it like that and they squawk you have ample precedent to prove that you are right.

Hey, if it works in your Pitts/Staudacher/Extra/Sukhoi/Decathlon where you really NEED it for negative g's, it should work to hold your lap belt down.

Good luck

JFC

ASEL IFR

ChrisBennet · ChrisBennet's Garage

I have my subbelt eyebolt just aft of the sub strap hole in my seat. It is NOT comfortable there. I am moving it forward some but this is complicated by the presence of the DME box.
-Chris
-86 911

orbmedia · 03-08-2002, 08:52 AM

The sub belt should be mounted within 20 degress of the slot in the seat according to the instructions that came with the Schroth 5 point system.

widebody911 · widebody911's Garage

I can't speak to the mounting location, but I have to ask: is it me, or is a 'properly' mounted 5-point extremely uncomfortable in the nether regions? I have my sub strap going over the front of the seat, but when riding in cars in with the proper seat slot, it felt like a large, unkind, person of indeterminate gender had me by the unmentionables, and was treating them in a manner unbefitting their station in life. Is this normal, or am I suffering because of my unusual endowment?

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by widebody911
I can't speak to the mounting location, but I have to ask: is it me, or is a 'properly' mounted 5-point extremely uncomfortable in the nether regions? I have my sub strap going over the front of the seat, but when riding in cars in with the proper seat slot, it felt like a large, unkind, person of indeterminate gender had me by the unmentionables, and was treating them in a manner unbefitting their station in life. Is this normal, or am I suffering because of my unusual endowment?

If the sub belt is in the right place it doesn't have to be uncomfortable. My passenger side substrap isn't uncomfortable. My driver's side is. I was looking at moving the driver's side belt today when it occured to me that a double sub belt might be the solution.

orbmedia's mention of the Schroth instructions prompted me to look at them. I think everyone ought to read these instructions. They specifically address practices that are wrong/dangerous - things that I see a lot of people doing.

orbmedia · 03-08-2002, 12:04 PM

Thanks for posting that Chris. Only a small percentage of installations at the DE level do it correctly. If you cannot do it 100% correctly then you are better off using the stock belts.

Formerly Steve Wilkinson · 03-08-2002, 02:49 PM

I assume that means that any installation of a five-point harness like mine is dangerous if you have seats--i.e. my Recaros--that don't have a hole for the sub strap. This I never knew, and I'm not sure I believe it, since the Simpson illustrations show the sub strap passing over "the front rim of the seat," and I assume they know what they're doing. Nor have I ever seen an aerobatic airplane with a five-point harness--and I've seen and flown many, including jets--that hasn't passed the sub strap over the front rim of the seat.

Stephan

89911 · 03-08-2002, 03:35 PM

I agree with Chris above. I have Schroth 5 point belts used with Recaro SRD's. When mounted, I never would know the sub belt is there. For comfort, the location of the sub belt pass through is more important then the location of the mounting point for the belt. Your better using 4 point belts then letting the sub belt go over the front of the seat. The purpose of the sub belt is to keep the waist belts down were the belong when you tighten up the shoulder belts. A belt that was over the front edge of the seat would be pulling against these belts adding slack in the set up.