kurt M

This portion of the thread has gone fully off topic! Guy wanted to use straps for AX...

Yes in the right car with the right equpment thanks to guys like you that make better and better equpment as time goes by. I think you are likely right but I don't think a 914 is it. Show me a 914 that is not a full on pro nastycar tube frame type rig that can take a full on header into a wall at 80 mph and have the car remain intact. 80 to 0 in 0.03 seconds. What are we talking about in Gs here 90, 100 110? That is a (no pun intended) stunning amount of energy and a very short time and distance to deal with it. Seat, head, neck, chest, pelvis, brains (optional), *****, all fully contained in a small pile of crushed unreconisable sheet metal with a motor mashed into what was the front after using the driver as the crush zone. 914s have almost nothing in the front other than a gas tank to absorb energy and no roof to prevent the driver compartment from folding. Early 911 or 912s are fold up cars as well roof or not.

Check out a low speed impact into a hard surface here. . www.heald.uk.com/videos.htm A truck is used. Go to crash testing of roadblockers and bollards.

John thanks for the post and info.

gbaker

Kurt,

Ah yes, the 914. Whenever I drove mine (4 cyl 2.0) I felt I was being trailed behind a plastic gas tank, which was the case.

Your guess of 80-110Gs is probably spot on. The Delphi sled uses a 45mph delta in about 33 inches to generate a 70G pulse with no crumple zone, so you are in the right neighborhood with a crumple zone.

It's a big hit to be sure, but with the right gear the driver isn't even close to the injury level. For that we are probably talking 120+Gs. Definitely not 914 AX range.

And yes, we are OT.

David 23

RedlineMan, I called Pyrotect, and they will send me the proper sub belt. However, they suggested that over the front of the stock seat was better than cradle method. They said the shoulder belts could loosen in an incident with the cradle, as the legs could move enough to loosen the shoulder belts. I am going to set it up both ways for my wife, and let her see what she feels more comfortable with (physically and techically). This has all been an excellent discussion in my opinion.

rockitman

Damn...guess I won't pursue the 914 track toy option

RedlineMan

OK... now I've heard it all. Please, I beg of you; try and get a detailed and technical explanation of this phenomenon they are warning you of, because I have never heard such a thing. If their belts loosen in one setup or another, how good are they in the first place? I am not aware of a particular type of cinch merchanism that is prone to loosening drastically more than another, but if they use them, I want no part of their product! Unless I am far less informed than I think, this is patently rediculous? Here is why I think so.

I can't see how the sub has anything to do with HOW the rest of the belts are loaded, only in how FAST. The sub CAN differ in what part of the system is loaded first, but I do not see any way that the sub will change the amount of loading at all. What certain sub arrangements DO accomplish is to load the entire belt system much more quickly, which brings on full restraint much more quickly. A GOOD THING.

You basically have two sub choices with a stock seat; over-the-front or cradle. Over the front can be done with any strap variation. Whether it is a single, V, T, whatever... the result is the same. All they do is hold the lap belt low, and not that well at that. There is no direct body control with a single sub on a stock seat.

Because you are sitting on them and wearing them "pre-tensioned" against the groin (the pelvis is an excellent hard point), a cradle sub will stop forward/downward rotation of the hips MUCH faster. Stopping this rotation tensions the shoulder belts faster, stopping the upper body faster, and tensioning the entire system faster, particularly if the sub attaches directly to the lap belt.

To sell someone a T-sub and then say not to use it as a cradle is like buying wine to wash your car. It makes no sense to suggest a setup (sub over the front) that we are in the process of deciding is not very efficient. The T was MEANT to be used in cradle fashion. That is its raison d'etre! I flat just do not get it at all?????

By the by... I can tell you right now that if you properly fettle a cradle setup with a stock seat, your wife won't like it. They must be worn fairly snug to the groin, and are NOT "comfortable." However, if the idea is to be safe, then you will have to live with it. If anyone just likes the idea of having a sub, put it in the glove box, for all the good it will do mounted any other way!

Guys... help me out here. Am I missing something?

Bull

RLM, I don't think you are missing anything! That is crazy talk, which I would like to hear them explain further. Unbelievable!

David 23

RedlineMan and Bull, that was not my opinion, I have agreed with your points and perspective. I am only relaying what the guy at Bell Motorsports told me when I bought the t sub. I didn't really want to get into an argument with him about it, as I am not much of an expert. I believe he was suggesting that if the sub belt was holding the lap belt down, from being pulled upward by the tensioned shoulder belts, and the sub's tension was being controlled by sitting on the belts, then the shoulder tension could be changed by the legs releasing tension on the sub straps. I don't think I misunderstood him. I have never used the cradle, so I didn't have any way to argue or agree with him. However prior to getting proper GT3 seats, I tried a sub belt in my 993 over the front of the stock seats with not very satisfactory results, so I tend to agree with both of you about that NOT being a good solution.
My wife has mentioned several times she wanted the sub belt added to her harness, and has used the one in my 993 often. I will install the cradle for her, as I think your points are well made and valid. I think trying to get a slot put in the seat of the stock seat would be a better solution, and perhaps I should start investigating that route.

shiners780

Forgive me if this has been mentioned already. Why hasn't anyone designed a seat with built-in harnesses? Harness routing and mounting issues would be mute. The harnesses could be replaceable to comply with dating issues. They could put some type of tether straps on the back of the seat to attach to the rollbar/cage so as to reduce the forces on the mounting bolts. Better yet, a solid built-in seat brace to be attached to the bar/cage. Hell, they could probably even figure out how to incorporate some type of H&N system right into the seat as well. Rather than a mish-mash of components, you would have a complete system designed to work as one with complementary components.

No, no, I know...How about getting rid of the harness straps altogether. Use a retention system like they have on rollercoasters that is attached to the seat, gets lowered over your torso, and locks into place. No belt elongation, no mounting or routing issues.............................um, ok, I've been up way too long..............must...........sleep...............

RedlineMan

Yes;

I knew that, David. I was questioning THEM, not you.

So, they are thinking that the sub will not be tight if you use it cradle style. Perhaps they have a point in that most people might want to cheat and keep it loose to mitigate discomfort. I really don't know.

The fact is that if the sub is tight enough to create a snug cradle, holding the lap belt low over the tops of the thighs and wrapping your hips, butt, and thighs in a snug parachute-type harness, that will not change unless those belts stretch. If the sub holds the lap belt low, the shoulder belts are also tensioned (pulled down) in an equal fashion. I don't get their problem.

Tight is tight.

-----------------------------------------------------------
"Belt Seats" are coming!

Bull

David, I too was questioning Bell Motorsports/Pyrotech. No intention to shoot the messenger. Sorry for not making that clear.

kurt M

There sure is a lot of "information" out there....

fatbillybob

I think this is a very important quote for all you instructors to heed. It is full of common sence and helps students who really do not know any better. Teaching people to drive is only one part of the equation.

kurt M

Very true. Now all we need is a concise line to teach. As is evidenced by this thread and many like it in the past in this forum there is quite a range of what is considered "safe'. From full race W/H&N at your first DE to no race seat = no harnesses to no roll bar = no harnesses to harnesses OK if in right to show up bone stock in a 67 912 W/stock original lap belts and no headrest. (I had a student car with just that last setup for a HPDC. There was a slight change to the "stock belts" rule the next year)

My standard line to my students is safety expenses should be = to or well in excess of any performance expenses for the first couple of years.

Capt. Carrera

you know, I can boil it all down very simply....

• Roll bars and race seats are good things for safety.
• Subs run over the sides of the seat is explicitly described in the SCCA GCR as a set up that will pass tech.
• With sub-belts run over the sides of the seat, and under your legs, moving your legs will not change the tension on any belts.
• subs run over the seat sides is a better set up than a single sub.
• A race seat designed explicitly for dual subs is good.
• Stock seats can easily spread the shoulder belts on a race harness too far apart to be effective.
• Most importantly, running the sub (or subs) over the seat front is a very, very, bad thing. Don't do it.

CO951

Ok, let me see if I can get to the bottom of this, because I’m in the same situation where I don’t have money for everything now. Please give me your opinions on this with a yes or no answer and brief explanation. As a beginning to intermediate DE driver with a basically stock street car and stock seats, would I be safer with a 6-point harness than I would with the stock 3-point belt?

Also can you recommend a good harness at a good price?