racergreg

Time for new belts in the track car. Should I choose 5-point or 6-point harnesses? I participate in PCA time trials, and would like to move to some POC events as well. Any rules issues you know about?

Thanks for any insights you might have.

vegasgolf98

Depends on your seat type. 6-points were really developed for Formula style cars where you lay-down more and not the more upright seating position of sports cars. Some seats have wide openings that a six points will work and spread the load out, but usually 5-points are the way to go.
Not a big functional difference if you look at the designs closely, but using 6 points, when the design of the seats is for 5 points could lead to extra stress being placed upon the seat. And that might not be the safest route.

prg

Bear in mind my only experience with 5 and 6 point harnesses is in formula cars with a more "lay down" driving position. A six point harness is markedly more comfortable for a post-pubertal male. The central crotch strap is uncomfortable at best, and I'd be a bit worried about it in an accident.

Geo

The 6 point harnesses are not for "lay down" type cars. They are for all cars. The latest safety testing has indicated that a 6 point significantly improves safety. And I'm not talking about "the boys." A properly installed 6 point threads the crotch straps back through the lap belt holes in the seat. What the 6 point does is better control the pelvis, and this in turn makes the shoulder straps work on the shoulders instead of the rib cage which is much weaker. These are not my words, but those of Doc Melvin, the leader in driver safety in this country.

ltc

5 points do not appear to be in favor:
https://rennlist.com/forums/racing-and-drivers-education-forum/126126-notes-from-presentation-by-tom-gideon-gm-race-safety-eng.html

To recap on the straight-line stuff, you need (for best protection) a 6- or 7-point harness (properly secured, of course), H+N restraint (of which the HANS is the best for this impact, according to their data and tests - note at this point that I have an ISAAC, not a HANS), and the proper SFI padding on cage bars (though this comes into play more on lateral hits). The 5-pt harness is NFG - no good - compared to the 6- and 7-point; the added movement allowed more than doubles chest compression, from an average of 20mm (with a 6-pt) to about 50mm avg with a 5-point. This is about 2 inches. This also happens to be where the sternum will break. The solution to preventing the sternum breaking is the 6-point harness, not the sternum strap. Actually, in their tests, the sternum strap shows potential to injure the neck. Don't go there, kids!

FWIW, I recently ordered a Schroth Hybrid 2 Titanium 6 point (was built in Germany this week and will hopefully have it in 1-2 weeks).
http://www.schroth.com/english/produ...ogy_hybrid.htm
http://www.schroth.com/produkte/raci..._hybrid_II.htm

The hybrid sub belt mounting is comfortable, based on comments and a test fit with the harness.

I have a Recaro ProRacer SPG seat, which supports 4,5 or 6 point belt mountings.

RJay

I had a recent conversation with Joe Marko on this subject. His strong recommendation was to go with 6 pt belts. The reasons are fairly obvious. A six point, if properly installed will under load put pressure on your bones, wheres are a a five point will rely on your manhood. Dunno about you, but I think my nads are worth an extra $50 or so (even if there not getting as much use as I'd like these days... ) I'm moving over to 6 pts when I move up to a hans later this year.

Oh yeah and Joe pointed out that the 6 point does a far better job of keeping the lap belt where it belongs, on your hip bones. With a five point the tendency is to over tighten the shoulder straps and the lap belt rides to high. If that happens the belt put pressure on the soft tissue above the pelvis and can cause internal organ damage in a crash.

RedlineMan

Hey;

A modern 6-point (see below) can be configured successfully in a sedan, and is actually the safest type of belt system you can use.



The type pictured should be arranged in a cradle type install where the sub belts mount behind the driver, and he actually sits on them. These can pass though custom holes in a seat and mounted in a remote location, or even through the lap belt holes to where the lap belts mount. As with any sub, the cradle should be adjusted as short as possible, in this case so it is fairly tight to the drivers inner thighs when everything is latched up. This system, properly installed and adjusted, has two benefits.

First, it helps keep the lap belt low over the hips; no different than any properly adjusted sub. Second - and MOST importantly - The cradle system DRAMATICALLY INCREASES the effectiveness of the harness system, and the occupant's safety. This gets kind of involved, but stick with me.

When a car crashes, there are numerous things going on. First, the upper body will impact the shoulder belts as it is thrown forward. The driver's legs - being quite heavy - will also be thrown forward. Because they naturally want to snap to a straight line beween the mount and latch, the shoulder straps place a downward force on the drivers torso. This combined with the forward movement of the drivers heavy legs causes the hips to rotate down and under the lap belt. Follow me?

The upper body moves downward as the hips rotate out and under the lap belt. The entire body stays in motion, and this is the key and injurious point. This is the definition of "submarining" in a sedan. Not the same as a prone position open wheeler, but dangerous for other reasons.

Modern crash testing has shown that full, complete, and rapid retention is the safest way to go. To do this, the length of time that the body is in motion must be reduced as much as possible. With a normal through-the-seat-base install, the driver would eventualy impact the sub strap with obviously painfull results. However, this strap would do too-little-too-late to reduce the time span of retention.

The cradle type system stops the hips from rotating forward MUCH sooner in the event, and so the rest of the belt system will become tensioned much sooner in the event, dramatically reducing the building of damaging kinetic energy. With modern low stretch materials, and the cradle sub system, surviveability is increased many times over conventional systems.

A standard 2-point sub can be configured this way, but is not as comfortable or "roomy" as the offset cradle type. A standard single sub should be adjusted as short as you can get it. If the belts are hard to get hooked and the lap belt digs into your thighs when you cinch it all down, you've got them right!

I know... more than you bargained for. Still, it is the cutting edge. A couple guys beat me to it, but this is a more indepth extension of what Geo correctly offered.

924RACR

Correction, John - the safest belt system is now the 7-point!!!

Recent development, and is even safer than the 6-pt, but hard to find it seems. Imagine combining the sub straps from the 5- and 6-pt. Provides even better control of the pelvis motion, which is critical as noted. I'm hoping next time I get my belts rewebbed from RJS, they'll be able to swap in the 3-pt sub belt.

mitch236

Man, I just can't keep up! Now I need 7 point? At this rate, it's gonna take me 20 minutes to strap in!

Edward

Great info, and great thread! This is all very interesting, and very timely, as I just put in a new Sparco seat. So maybe I'll "retire" my 5-pt harness to passenger duty and get myself a new 6-pt one. If I understand correctly, if I don't want to cut holes in the seat I can route the sub straps back down the slots for the lap belts, but secure them on their own mounts, say eye bolts, to the floor or to the tunnel and door sill? Any "better" place to get a 6-pointer or just the usual places to get safety stuff? TIA

Edward

Noel

Why couldn't you just mount the six point sub-straps to the same point as the lap belts? I've heard others offer this as a mounting solution. Since the job of the sub (in a sedan) is to keep the lap belt down around the hips it won't see the loads of the lap belt.

racergreg

Thanks to all for your thoughtful and informative advice! Sounds like 6-pt is the way to go for now. I was not aware of the cradle-type mounting, but it makes sense and sounds like a good plan.

Just to be sure, is it ok to mount the sub straps to the lap belt mountings? Or would it be better for the subs to have their own mounts?

vegasgolf98

It is amazing how things get misinterpreted. People read what they want to and not what is actually said.

1) 6 points were originally developed for Formula cars (that doesn't mean they are not better for sedans)
2) Sorry, six points CAN be more dangerous than five points, if you opening of your seat bottom is not wide enough for the six points. To put both straps though a narrow hole, does not protect you more and this will place more stress on the seat (not the strap) and can break it.
3) 6 points are the way to go if your seat is designed to handle it, make sure first. If you put a 6 point into a seat that is not designed to handle them, then it is more dangerous.

Look at the picture that Redline man posted. Do your seats have that wide of an opening? Remember safety is a system, not just the sum of best components.

RedlineMan

Indeed, Vaughan -

7 point should theoretically provide the lap belt positioning of the single sub with the cradle properties of the double sub. However, try finding a 3 point sub (as you mention) or more diffuclt yet, a seat that is designed for their use. Unfortunately, this renders a 7-point a bit of a lame duck for many people unless they are just starting or can afford to scrap what they already have.

Mitch - You have the distinct advantage of having listened to my excellent seat advice , and as such have one of the VERY few seats (the only one I actually am aware of) that has 3 sub holes!

Having said that, and regarding the cradle type sub arrangement, I am not happy with the holes for the outside straps of a 2/3-point sub. To achieve the proper cradle, the tails of the belts must go under (be sat upon) and mount behind the driver. There should be as little change in direction in the strap as it passes through the seat as possible. The holes in a seat base directly below ones belt buckle do not provide this rear mounting nor cradle retention, as they are usually not placed rearward enough.

I have installed a standard 2-point sub (sometimes known as a "V" sub) in a cradle arrangement. While the standard 2-point does not offer the offset (or room for your manhood, if you like) of a purpose-designed cradle sub (known as a "T" sub, pictured), they will provide some better hip retention than a sinlge sub going straight down.



I am not sure if there is any advantage to one mounting point over another. Simpson says it is permissable to mount their cradle sub to the lap belt mounts. I would also think that other points may work well too, as long as they do not introduce too many changes in belt direction from straight.

It's awfully difficult to get these cutting edge systems into anything but a puprose built race car where appropriate mods can be made for their installation. Still, they do represent the zenith in safety harnesses.

Geo

I give up. You're right. People make things up. All I can say is read the stuff publish by Dr. Melvin or attend a seminar or get all the info you can from someone who has attended a seminar. I have not heard any mention by Dr. Melvin of requiring a special seat to get the advantage of a 6 or 7 point harness. If I've missed it, please point me in the right direction.