6 point harness install

[ap911]

I am upgrading the safety equipment for my otherwise stock 84 Carrera for DE/track use. I will be using a DAS roll bar (installed) Sparco Evo2 seats and harnesses.

I did a search (both Pelican and internet) and now I am even more confused.

It appears to be universally accepted that 6 point harnesses are safer than 5 points. I also believe that the substrap in a 5 point harness must be mounted to the floor directly below (+- 20 degrees) the substrap opening in the seat.

It is the installation of the 6 point harness that has me confused. Many manufacturers recommend mounting the 2 sub straps to the floor 100mm apart in a similar fashion to the 5 point sub strap. Schroth for their formula harnesses state that you should run the straps under your thighs and out the side holes of the seat to the outboard mounting points for the seat strap.

The SCCA rules describe both ways.
Can you mount the sub straps to the factory rails?
What is the best method?

I want to do what's safest. I don't care about drilling.

Any advice appreciated.

[DUK]

The way we do our Willians 6 points is to got directly to the bottom of the seat 3" off the centerline and 3" behind the opening in the seat. I'm not familiar with sparco seats so I don't know if this is feasible. The main concern is to keep the two straps as tight to your groin area without cutting off circulation. Hope this helps.

[ap911]

Thanks, and yes it does help. Intuitively that is what makes the most sense. I will admit. however, that I am a little nervous about the "keep the two straps as tight to your groin area without cutting off circulation" part.

[Zeke]

6 pts. were initially for drivers in a more prone position such as in a formula car. In that situation, there is a problem with the driver sliding forward and he/she needs something better than a strap "up the middle." (Ouch!)

There has been a lot of discussion on belts here and on the racing forum with not much of a definitive conclusion. What I say is my opinion. If there is not hole in the bottom of the seat, he belts may be used, as you say, under your thighs and out the sides.

One would think that a V-belt type of installation through the seat hole would be redundant. However, 2 mounting points spread apart below the seat are better than one. If you analyze the forces involved in restraint, you would see that the sub belt is very important in balancing the pull from the shoulders and keeping the lap belt from riding up. It's a big web.

Again, just some thoughts to consider.

[JP911]

I use 6-pt belts with a Sparco Evo 2. I have the anti-sub belts and the lap belts attached at the same place (eye bolts where the factory seat belts and receivers attach) and I run both through the holes on the side of the seat. The setup works well and I decided on it after doing quite a bit of research and asking questions at DEs.

[Jack Olsen]

The traditional 6-point belt and the sit-on-it kind are two different animals.

The weak part of a 5-point system is that the sub strap (which sees 1500lbs of force in the "average" 30-40G hit, according to a recent Rennlist post) is often mounted to the floor sheet metal, which is going to probably distort a great deal in some types of impacts, compromising the designed-in characteristics of the harness and your harness/seat system. Remember, the floorpan often burps an inch or so from impacts, and can be set back in position with a few good hammer hits. That's probably not ideal for holding belts.

6-point belts can be mounted closer to the seat base, where I would guess there's more strength.

[ap911]

JP911. Both Schroth and SCCA say that is an acceptable method. If I understand it correctly the substraps run from the camlock between your legs then under your thighs and out the side holes to the side seat belt mounts. If I read the fine print correctly it is best used with the formula type 6 point harnesses.

Unfortunately, you only get one shot at getting this correct. Thanks for everyone's help.

[ap911]

I take back my last post. The sit on method is only for a harness (formula type) designed for this use and even then it is intended for open wheel type cars.

I will go with a 6 point with the substraps mounted to the floor with proper backing and approx. 20 degrees back from vertical down from the groin.

[Wil Ferch]

Milt:
small point... I think you mean supine instead of prone.....no ?

Prone is lying flat on your belly..supine is laying back "on your back"..so to speak.

Otherwise....good points.

- Wil

[jester911]

If I read the new PCA rule taking effect in 2008 correctly you are not going to be allowed to sit on the sub belts. It will be required to have the proper holes for these in the seats.

I understand the 6 point being better than 5 but do they make seats with 2 sub belt holes or just one big slot?

I am in the middle of getting my car ready for DE's as well and I have not purchased seats yet. I bought 5 point harnesses but I figure I could just replace the sub belts with the dual ones.

I have yet to see anyone either here or on Rennlist have a definitive answer for the 6 point harness through the seat.

[Zeke]

Originally posted by Wil Ferch
Milt:
small point... I think you mean supine instead of prone.....no ?

Prone is lying flat on your belly..supine is laying back "on your back"..so to speak.

Otherwise....good points.

- Wil

Thank you, seriously. I have never seen that word, but I have now noted the difference.

Back to the belts, Jack said it all. Even if the 2 belts make a V and come up through a common hole in the seat, the wide spread mounting will be much better than one belt attached to a 3/8ths bolt and fender washer in the middle of the floor pan.

I have to editorialize a bit at this point. I do understand that liability issues drive these changes, but if one cannot go to the track and drive a street prepared car (don't they have class for that?), then I'm out of DE's, etc. I've enjoyed my brief episodes at the track in a car after 30 years of driving race karts out there. Now, in a kart, there are no belts whatsoever just like a motorcycle.

I've lived this long..........

[Green 912]

The sit on system would be OK per the PCA rule. The rule requires holes in the seat where holes are needed. The cradle system offers better lap belt placement retention than traditional subs even in a upright road racing position. The cradle type systems are not as prone to the belt and body movement displacment as they move with the body and maintain the lap belt to pelvis placement as the body moves and shifts. The job of the sub strap is to keep the lap belt on the pelvic bone. As you undergo an impact your body moves around, changes shape and the belts all elongate some. Your legs also pull on you pelvis and cause it to want to rotate into a more supine position. This all can add up to the lap belt being pulled up and off your pelvis. This is bad as you are now holding your body in place via the soft stuff (your guts) rather than the frame. Kinda like putting the lift arm lift pads in the middle of the pan on a nice early 911 rather than right hard points.

Milt you do not have to install a 5 or 6 point to run a stock or nearly stock Porsche with PCA. The seat and harness rule was to stop some unsafe combinations that were showing up at the track. Fact is stock belts are good but do not work as well protecting you in an impact event and far less so in an off angle hit as will a good seat and harness system. With a car the car offers protection from the outside world hitting you. What you need to protect yourself from hitting the inside of the car. A bike or a Kart do not offer any or much protection and the best thing you can do overall is get thrown away from the bike or Kart so as not to be hit by them too.

[ChrisBennet]

I'm going to think twice about getting (new) harnesses for the track now that PCA is mandating that your replace them every 5 years....
-Chris

[unclebilly]

Sorry to hi-jack. I need a harness for my car for this year's Solo season. I am considering the Shroth 4 pt and running with a harness bar and my factory seats. Is there any way I could run a 6 pt harness with my factory seats and a harness bar?

I really don't want to install racing seats because I just spent a pile of money reupholstering my factory seats.