Mark in Baltimore

Wasn't there a line of reasoning that states if belts stretch, they will not continue to hold you in should you have subsequent impacts after the initial hit?

chris walrod

Of course belt length effects the amount of stretch, as does velocity and decel rate, but generally, (IIRC) initial impact stretch for 3" belt is something like 25%, ~12% on second impact. Stretch in competition belts is to reduce decel rates and is why they must be replaced after -use-. The below illustration is for OEM type 3 point and just an example..

Ray Calvo

You don't. You NEED some support to keep the shoulder harnesses at your shoulder height. And without the sub-belt (5th or 6th belt) securely mounted to a under-seat location, the lap belts/buckle will ride up into your gut in an "incident".

Stick with your stock seat/3-point seat belts if you won't install a proper system.

chris walrod

Agree with Ray. Car manufactures spend a lot of time and money designing AND testing typical three point restraints, with standard issue, folding seats. Once any one component is substituted, it may alter results, unfortunately.

Installing safety equipment is a slippery in and of itself, at least the way I see it.

~3 years ago, I wanted to drive a track event with the PCA, it was the first Cal Festival of Speed at Calif. Spdwy. At that time, all the PCA mandated was 5 or 6 point belts. So I started to plan getting my car legal. I have this bad habit of thinking about installing something, and sometimes think myself into a corner

Anyhow, I felt this PCA rule was odd since they allow OEM seats to be used with 5 or 6 pt. belts, even without pass-throughs in the seat for proper shoulder belt geometry. Heck, even a roll cage of any type was not mandated.

So my thoughts were, if I were to install such belts, they need to be anchored well and shoulder belts held at ~shoulder height (and width). Harness guide bar here I come, right?
Next on the shopping list was seats with pass-throughs for shoulder belts. Sure there are afetermarket folding seats available, but I felt a one-piece seat would be best for what I want to do with the car.
Fine, two new seats it was.
Now that I had one-piece seats and 6 pt. belts, I did more reading here in the archives and spoke with other experienced people at work. Discovered that OEM seats generally are designed to collapse in the tragic event of a roll-over. Mostly to keep people from getting smashed if the roof would collapse far enough.
The seats have got to give--.
At this point, I am fixed in a upright position (one-piece seats), held in place by 3" belts, criss-crossing my body in all directions, I felt I needed something to assist the roof structure from caving-in on me.
So, short story long, I installed a roll bar. Added bonus of a roll bar is that it also serves as a cool camera mount

Sorry for the ramble, but this is how I view it..

aam993

That is exactly my thinking at the moment - it's either all stock or 6pt belts+rollbar+seats with belt pass-through holes.

The only question I still have is whether there is a way to avoid drilling a floor underneath the seat to have sub-belt installed from 5/6-pt harness.

ppressle

Excellent line of reasoning Chris. And with used DAS bolt in roll bars going for around $500, it was an easy call for me...

Monique

Here is a pic of an RS Komfort with 6 point harness. Lap belts bolt to the diagonal belt points, submarine strap is bolted on either side of the ECU under the seat.

Note the shoulder hook points are in the aft ledge... if you have no rear seat. No need for a harness bar if you have the Recaros. Car had a full Heigo cage at the time.

chris walrod

There is another alternative to drilling the floor for sub belts. But, I never found a way to avoid drilling two 7/16" holes in the tunnel for inboard lap belt mounting..

For sub belt mounting, I used a bolt-in cross bar from the 996, GT3 RS. They are available from Gert.
See image attached. Warning, they are too wide for 993 seat tracks, but modifyable to work. Just took some time and cleverness Also, they do not require relocating the factory ECU..

aam993

For lap belts? I thought that Brey Krause Tunnel Side Seat Belt Mount Kit R-9001 http://bkauto.com/porsche/r9001.php allows to reuse factory tunnel side seat belt mounting points

Interesting! Will read about it. Can you give an idea of how much time and cleverness is needed?

Thanks!

Greg H.

And then there is the Schroth DOT approved 4 - point harnesses . What is the story with those?

Greg H.

aam993

Thanks for the picture, Jean-Pierre. Is the RS body different from regular Carrera in having the holes for those submarine straps bolts? Do you have any pictures of those connections in your RS? Thank you!

akolodesh

Greg,
I asked about these on the Rennlist board some months back but didn't get much of a response. They seem to be a really good product in that the anti-submarine function is already built in and therefore can be driven on the street. I almost went with these but decided to go with Sparco 5 points (because they are on sale right now -$99 for 3" camlocks http://www.speedwaremotorsports.com/...Harnesses.asp).

Edward

On the subject of belt stretch, according to safety guys I've spoken with, routing the shoulder belt to the rear seatbelt mounts is "acceptable" practice, but obviously presents a compromise, allowing considerably more stretch in an incident as opposed to wrapping straight to a rollbar (welded-in) right behind the seat.

Chris,
Great pics of seatbelt stretch and Gert's bar. Nice!
Funny about where you "were": I am sliding down that slope now and budgeting for a weld-in bar (or bolt-in cage like Safety Designs ...can't decide).

Freebie Alert:
As far as the inner seatbelt mount, I have a pair of those BK mounts that I would gladly hand over to anyone who wants them. They were given to me, most generously, by E.J., so I 'd like to give them to someone here who could really "use" them. Keep in mind, though, that they are designed to be bolted to the seat, but if you have other ways of mounting/using them, they're yours. For example, I was able to use them for a couple of events on my "new" SC trackmeister, where the seatbelt receiver bolts into "ears" connected to the tunnel, not directly on to the seat itself like our 993s. Be creative! My personal stipulations:
- you promise not to sell them
- if/when you "grow out of them," you give them up free to another newbie track hound.
Let me know.

Edward

akolodesh

Another option for someone that doesn't want to go to the expense of 5/6 point harnesses; harness bar/ roll bar; seats and installation is the CG Lock product for their oem belts. I just order this for street driving. Have not gotten it yet to test it out.
I ordered mine from www.automotion.com for $41.95. Here is a picture of it.

Monique

The bolt points were factory drilled on my car. As for pictures of the fitment, here they are. (Note the rings on either side of the ECU) FWIW, the 6 point harness was a PITA for street use not to mention a "crotch overheat" problem. Hence why the setup went to a RLer who recently built a monster

Alex, if I tracked more often, your suggestion would be great with the Recaro sports.