Sean F

I've got an 82 SC with the following on the way for installation: DAS rollbar, Recaro Profi SPG seats and Schroth 6 point harnesses. I've done the search on this and found a lot of different points of view on the harness installation (especially the sub straps). Does anyone have pictures/descriptions of a similar install? I'm curious about the lap belt attachments as well as the sub straps. Seems like several people did similar installs, but I'm not sure from the posts what they ended up doing and if they're happy with it.

Thanks for the help,
Sean

}{arlequin

your schroth should have come w/ instructions. mine have the sub straps mounted to the same locations as the lap belts. they are also routed through the same holes in the seat as the lapbelts.

according to schroth, it's acceptable to do it that way.

M758

There is a picture I posted a long time ago from schroth that cover's proper mounting.

Sean F

Just so I'm clear, you actually sit on the sub belts and route them through the same openining and attach at the same place as the lap belts? But, the best way to mount is down to the floor and 20% behind the buckle. Why wouldn't you mount to the floor instead of the lap belt point?

}{arlequin

oh oh.... i may have confused you. i am only referring to the new generation of 6-pt schroth belts which i think are called "hybrid"

these:
http://www.schrothracing.com/products/competition/1594

i am not sure whether the 6-pt belts which are actually a 5-pt at the buckle (due to the use of the t-bar) utilize the same method.
http://www.schrothracing.com/products/competition/1599


if you're asking about the "hybrids" then yes, i do sit (somewhat) on the sub straps. they run under my upper thighs and link up w/ the lap belts/cam assembly. see the closeup pic on the schroth link

i think that is the case with 'traditional' sub straps, but not with this newer design.

Don Plumley

The optimum way to mount to limit pelvis movement in a crash is 20 deg back from vertical, through the seat hole, about 4" apart. Parachute style (around your leg back out the lap belt hole) is allowed by some GCR's, but not optimal.

RedlineMan

Hey;

WHICH 6-point harnesses? Profi or Hybrid?

Regardless, if you follow the Schroth documentation, you will have the best setup available. Their guidance is the best in the business. No need to be confused by any other installations anyone else has done.

As Don said, 20 degrees back from the imaginary spine line. You may move the mounts closer together if your seat is very close to the floor. This will place the belts slightly closer together for increased inner thigh comfort.

I would pay attention to the angle at which your lap belts address your hips. If you are 6' or over, many times the factory holes are too far forward to achieve a proper 60 degree angle of address from mount point to hip bones (iliac crests). Proper mounts, properly placed, will have to be constructed if you want an optimal system.

Also, seat belt hole clearance should be checked when proper position is considered. You must factor in that the hips can project forward as much as 4" in an "average" impact. The belt therefore needs room to pivot forward without hitting the perimeter of the openning. These are very often overlooked aspects of proper belt usage.

I'm in the process of installing both Profis and Hybrids in a race car right now. Wait till you try to figure out the Flexi-Belt wrapping!

Any other questions?

car_slave

John, would you use a 5/6 point sub strap on a stock Porsche seat, or is it best just not to connect it? This would be for use in DE’s where a harness is not mandatory.

Thanks

bruinbro

Do you have a H&N restraint? If not, I would ditch the 6 points until you get one.

Bro

Sean F

They're profi not hybrid and the person I spoke with at hms motorsport mentioned that people have trouble attaching to the floor because there are electronic components under the seats positioned in a way to prevent the recommended installation. He also mentioned that some people install a bar that runs above the box between the seat rails to connect the sub straps.

N_Halbert

On a stock seat you should only use the stock belts. Many regions now require you to have a proper race seat if your are going to use a multi point belts (I know this a fact for the North East Region and CVR). Most do not allow you to run a harness bar with 4pt belts with stock seats. The reason being the belt run is too long and the belts spread outward over the seat causing sternium injuries. You sort of pop out through the middle. Don't even thing of using a 5/6pt system since there is no way to properly mount the sub strap and cutting through the seat does not count.

RedlineMan

Hey;

As subsequent posts illiterate, there are groups looking unfavorably on stock seats and harnesses. In many cases, such decisions are based on knee-jerk reactions by people who know less than they think. In this case, however - with the integrated head rest of the Porsche seats - perhaps they have gotten a bit lucky, for there is indeed precedent for such concern.

During an impact sequence, the shoulders will move forward and downward, forcing the belts onto the widening head rest. This combined with the shape change of the chest (shoulders sloping back in relation to the sternum) sees the belts moving outward and being simulataneously forced and slipping off the shoulders. This is far worse with shorter people, where it may not be a problem at all for the taller amongst us. The key is to keep the shoulder straps close together to reduce torso shape change, and the taller you are, the thinner the headrest is where the belts pass by it. So too do the subs have an effect on this.

The faster the belt system takes up slack, the shorter the interval of overal occupant motion. When the interval of motion is reduced, the force on the occupant is also reduced. When the force is reduced, the load on the belts is reduced. This phenomenon results in the forces of shape change on the chest being reduced, and may indeed reduce the likelihood of the belt slipping off. The sub strap is the absolute key to assuring that the belt system takes up slack as quickly as possible.

So, to get a sub to take up well with a stock seat only happens one way. Without a hole in the seat base, you must employ a double sub in a cradle arrangement that you sit on. It must be adjusted such that it is pre-tensioned. This means fairly tight, and it is not necessarily comfortable, but that is the deal. If you have a sub like a "T-bar", it will be a lot more comfortable than an older style "V" sub, for obvious reasons.

Do I think that 4-point systems have merit? Yes. If they keep you planted and help you concentrate, they are worthwhile. Just don't hit anything! Do I think that 5/6 point systems with stock seats have merit? Yes, for the same reasons. However, while they will be safer than a 4-point, they also can be less than completely helpful if things go wrong.

I personally think it is a bit overzealous to dissallow this arrangement. I am a firm believer in giving people the information to make their own informed decisions. However, there IS indeed some science behind the decision. When you consider what is on the line - in our stupendously litigious culture - it is not surprising.

car_slave

Thanks for the responses. My feeling was that in a major crash, a 17 year-old stock belt is unsafe compared a sanctioned safety harness setup. I’m 6 ft. tall so I’ll try not to crash too hard. I see that the Schroth website sells the nicer T-style subs for about $25. I wonder if they would snap into my Sabelt buckle? I might buy one just to find out.

PT

When I jump into student/other's car with 5/6 point harness and stock seats, I would use them but I ALSO wear the factory belts. The harness will help me stay in the seat better but I also trust the factory belts if any should happen.

Ed Newman

Most PCA regions will no longer allow harnesses with stock seats after the accident at the Glen last year and subsequest testing over the winter. Expect this to go 100% by next year.

DO NOT wear both 3 point and 5/6 point. This is very bad as the system are designed to work differently and you can hurt yourself worse.

Best thing to do is stock belts/seats until you make the commitment to move up to race seats and harnesses.

Also... pay very close attenion to how the belts are angled and mounted to the body. The strapping method where they connect after looping around a harness bar, etc. is also extremely important. I strongly recommend you consider having harnesses installed by a shop that caters to race cars. Not you average performance shop or dealer, but someone who actively races. There is at least some hope that they will get it right.

At the last DE I did, over half of the cars I looked at had some sort of problem with the harnesses. This is your life... don't end it by saving a few bucks or being cool.

P.S. The Scroth 6 point hybrid is a T bar for the sub strap.