TheKane

I installed two Schroth 6point harnesses in my Spyder. I also had the dealership turn off the seat belt chime.

When the seat belt is not connected, will the airbags deploy (both side and front)?

When someone is in the passenger seat and the stock belt is not fastened, the little "passenger airbag is OFF" light is NOT on (meaning that even with the seat belt disconnected, the airbags will deploy. Is this the same for the driver's side?

Here's a pic of the harness, if anyone is curious. I had them swap in the red pull-tabs from the yellow on the lap belts, and removed the yellow logo patches.

drcollie

Yes, the whole reason for airbags is because people won't wear their seat belts. They will deploy even if you are not fastened into the stock belts. For track events, you want to pull the power plug to the master airbag computer module, or have a switch wired up to defeat it. I have no idea where its located on a 987, but I used to do this all the time on my BMW M3 (it was under the rear seat in that car). Once you set the fault code by doing this, you will have to use a Diametric cable to clear the fault.

Duane

Alan Smithee

As I understand it, there are sensors in the seats identifying occupancy and weight of the occupant, therefore determining whether to activate the airbags and to what volume in the event of an impact; it is not the use of seat belts that does this. But don't take my word for it.

jrotsaert

To disable the chime I use $1 dummy buckles bought on ebay. The airbags deploy when there is a load. With harnesses however, I see no reason why this will be a problem since you won't be close enough to the wheel to be a problem with your helmet and the harness will prevent you moving at all - if done right
JM

s2ktaxi

are the Porsche airbags dual stage ones that will have a different rate of expansion depending on the load on the seat and if the seat belt is buckled?

brim

can you show a picture of where you attached the shouder belts to the car? Did you have a harness bar installed or is there a factory mounting point?

TheKane

Some quick notes:

1. The chime was turned off by the dealer. Easy. It seems the airbags will deploy, with or without the seat belt buckled (excellent).

2. The shoulder harnesses wrap around the stock roll bar, and the rear deck lid attachments on both sides act as a perfect separator for each belt. They clearly thought it through. Nice. The only hardware changes are the Brey-Krause seat mounts and the bolts for the lap belts. Note: I had to get the eyelets sewn into the ends of the lap belts, as the quick-clip mounts are too large to fit between seats and the center hump.

drcollie

Using a harness without a full cage and 1-piece racing seat that's bolted in is not very safe. But to each his own.

jrotsaert

I used the GT3 harnesses with longer bolts that go where the stock seat belts go and therefore did not need to put any eyelets.

TheKane

@drcollie - Huh? Yes, a full cage would be safer. What does a one-piece seat have to do with safety? Every racing seat in the world is a one piece and bolted in. And are you suggesting that there is no significant additional safety benefit to a 6-point harness if you don't have a full cage?

Sorry, but that's ridiculous.

drcollie

I've been doing track and race cars a long time, so I'll just say this without getting into an online argument:

Harnesses/Racing Seats and Cages are part of a 3-element safety system, and in the past few years you can add a HANS device to that to make it four. You really need all the elements.

A one piece seat does not break in a collision. Any seat that is on adjustable rails or has an adjustable back will break in a collision with an Armco barrier, car, etc, especially if the car is in a spin moving to the solid object back-end first. Drivers have been killed when their car is going backwards at the track - hits that solid object, the seat breaks and their helmet impacts the roll bar or B-Pillar and breaks their neck. That's why you want a bolt-in 1 piece seat, which street cars do not have.

As to adding in harnesses into a car without a cage, it restricts your movement in the seat (which is why I assume you are installing them). This is all good until you roll your car that has no cage in it, and the roof comes down/flattens out (or in a Boxster its going to be the windshield frame). If you're held tight to the seat and the seat does not break, you're dead from a broken neck if that car is sliding upside down for any length of time. If you have stock belts on, just the standard lap belt and shoulder strap - then in the event of a rollover and slide on the top, the driver will actually slide out of the shoulder belt to the right while the lap belt holds him in. When we get to the flattened car they're shaken up pretty good but prone across the console as the roof is flat to the car. I've been on the scene twice to witness this at DE events, once in a E36 M3 and another in a 993 TT where the roof was completely crushed flat and we pulled the drivers out of the passenger footwells.

I've been a DE instructor since 1996, PCA, NASA, Mazda Club, BMWCCA, Audi Club, Mini Club, and a paid instructor with AMG (Mercedes). Seen a lot. I will not ride with a student in a car that has harnesses and no roll bar unless he has the factory seat belt I can use. I actually prefer instructing in slower cars, because when a student loses something like a 987 at speed, things get real nasty going that fast.

Street cars were never designed to crash at speed. Most of the design parameters are for 25 to 30 mph impacts. You start crashing cars at 80, 90, 100 mph and you're in a entire new area of physics that the manufacturer never anticipated. My recommendation is to study and learn before simply installing things in a car and look at the negatives that can occur when its done incorrectly. Just because there is a bracket for your car to make it fit, doesn't mean its a good modification.

Experience is a good teacher. Good luck on whatever you decide.

-Duane Collie

Renn 951

Very good explanation, Duane! I would only comment that it's not a given that an adjustable race seat will break in a collision. The one-piece bolted-in seat will certainly be stronger and less likely to break, but in some situations (i.e. drivers sharing a car) the practicality may be an acceptable trade-off vs. maximum safety. But IMHO you've articulated the need to view everything as a "system" very well.