JBH

There are still a couple of points that just don't connect for me yet:
1. For those of you with full harnesses that drive your car on track and street: do you wear the harness or OEM seat belt when driving on the street?
2. Do you have the airbag disconnected?

OT: my 2001 BMW Mcoupe had a charge in the take-up reel which, upon impact, would shoot one or two cartridges to tighten the belt depending on a driver's seat sensor that determined the weight (heavy or light) of the driver. I think the same was true of the airbag - pretty cool technology, except those seat sensors only lasted a couple of years.

After seeing that video, I am thinking the Hans device should be required even for DE.

Z-man

As I stated before - most full harnesses are not DOT approved, therefore, you should not use them on the street, since your local authorities will frown upon that. It is not meant for street driving.

-Z.

Brian P

From my buddies who have been stopped in the street by authorities, they didn't seem to indicate that the DOT unrated belts were a problem. Instead, the authorities didn't take too kindly to the person driving a race car on the street.

For example, when you are stopped for speeding (the most likely thing to be stopped for) and the cop sees that you are wearing a 6-point harness and you have a roll cage in your car, he might tell you that you should save the racing for the race track. You can basically forget about talking your way out of a ticket.

mds

Not according to this DOT form:

"When an air bag is off, even belted occupants may hit their head, neck or chest on the steering wheel, dashboard or windshield in a moderate to serious crash. That possibility may be increased in some newer vehicles with seat belts that are specially designed to work with the air bag. Those belts, which are designed to reduce the concentration of crash forces on any single part of the body, typically allow the occupant to move farther forward in a crash than older belts. Without the air bag to cushion this forward movement, the chance of the occupant hitting the vehicle interior is increased."

Z-man

Yes, I know - it was my error in NOT saying that stock seat belts won't stretch AS MUCH as racing harnesses.
-Z.

Mike Buck

I can vouch for this. Although I talked my way out of any tickets and/or fines, I couldn't talk my way out of multiple repair orders. Took the easy way out and pulled the registration on the car. BTW: I wasn't speeding and the officer never indicated that was why I was pulled. I was simply pulled for non-moving violations like stickers on the windows . . . like 99.9% people have anyway. Once he had me stopped, he tacked on other stuff.

Why would one want to use 5-6 point belts on the street anyway? Other than, them being the only belts in the car.

JBH

I would use them on the street if they were safer. My logic says if they are safer on the track they should be safer on the street. That leaves open the question of whether the airbag is still required and provides any additional protection. If it does, I'll leave it, but I would rather have a smaller and removeable wheel.

On the subject of being street legal, the belts are only a portion of that equation - I am certain I am no longer at DOT prescribed bumper height, I am running European headlights, the seats are not DOT approved (but they have a FIA sticker), etc.

So Mike, when you were pulled over and issued repair orders, what were they?

SundayDriver

I don't know that I buy into that. Race belts can be either nylon or polyester (which stretches less than nylon). They both stretch a bunch. Every crash film I have seen of street belts shows equivalent stretch. What do you base your comment on? Is there some data somewhere on this?

SundayDriver

That logic would be flawed and here is why...

Stock belts and safety equipment is heavily tested.
Race belts with cages and helmets are heavily tested.
Mixing them (e.g. Harness without helmet) have no test data.

You can apply all the common sense and seat of the pants engineering judgement you want, but the fact remains - you are in uncharted territory when you mix. I don't know of anyone in this board who is qualified in safety engineering to offer a sound opinion on this. If you are going to mix, there WILL be unintended consequences.

Brian P

A simple example to back up Mark's point is that it can be INCREDIBLY dangerous to drive a car with a roll cage while not wearing a helmet.

Mike Buck

One repair order and accompanying warning was to remove all the stickers from any of the windows. According to the law, allegedly, the only legal sticker on my glass was the DoD registration in the lower corner of the windshield. All the other stickers I had, like my college name in the rear window and a PCA sticker in the rear quarter window are not allowed. This in a state where double 5% tint is legal anywhere but the front windows. He could pull every car on the road for that sticker thing. Gave me another warning for no front plate. He didn’t see this till after he pulled me.

Second repair order was for an unspecified problem with my exhaust. He just thought my car smelled funny (asked if I had nitrous three times) and wanted the exhaust checked. Pretty unbelievable he could determine my car stunk given our location . . .on an overpass in the middle of Baltimore about 50 yards from a paint plant. The car was shut off as soon as I stopped. He didn't look under the car or comment about sound levels.

Didn’t say boo about the rollcage, seats, belts (was wearing the 3-point, but the 6’s were visible), virtually bald Sport Cup tires, aftermarket steering wheel, etc… To satisfy the repair order, the car needed to be brought back to MD state inspection standards. Given I rarely drove it on the street anymore I just pulled the registration before it was suspended for not complying with the repair order. Frankly, with the cage, it wasn't very smart to drive it on the street anyway

Z-man

I did some research, and I was wrong about the whole stretch thing.
Not a whole lotta information out there, but here's what I found:

Regarding street belts:
According to ryan engineering (Link: http://ryan-engineering.com/main/Pub...uto/seatbelts/ ) the government standard for seat belts is 30% max elongation in the lap area, and 40% maximum elongation in the shoulder section. They found a 20% elognation on most belts they tested. (I am assuming these are street belts).

Regarding racing belts:
Seems most nylon webbing stretches somewhere between 15% and 17% under 2,500 lbs of load. (I think they are referring to most racing safety harnesses) Most racing harnesses are BELOW that standard. (Example: the Simpson Platinum system has a 7% to 9% elongation under 2,500 lbs of load.) Source: http://www.simpsonraceproducts.com/safety/

So, the bottom line is that racing harnesses and stock seat belts probably stretch in a similar fashion. Sorry for the confusion.

So the major difference between stock seat belts and racing harnesses is the mechanism in stock seat belts that either pretention or 'lock' the seatbelt, vs. the racing harnesses which are already typically secured tightly around the occupant. That said, I think it is safer to use either safety harnesses OR stock seat belts, but NOT both at the same time. Comments?

-Z.

Brian P

It sounds like some racing belts have half as much stretch as the street belts, and I bet the system as a whole as much less than that. I figure that the force of an impact is spread across many more belts in a 6-point harness than it is in a 3-point seat belts. With less force acting on each individual belt, there is likely less stretch in total.

Then again, I'm also pretty sure that accurate test data exists on it, we probably just don't have access to it.

Another point... As long as your body isn't hitting anything, more stretch is probably more desirable than less stretch. Imagine the extreme where the belts don't stretch at all. Your body would basically be absorbing the full impact of the crash. Having even a tiny amount of stretch allows the impact to spread across time. So, it's probably a delicate balance in providing enough stretch to slow down the impact yet not enough so that you don't hit other parts of the car. Presumably, one might argue that different belts might be better or worse depending on your body weight.

FYI, this is all hypothetical guessing.

Z-man

Major side track:
Brian - did you hear me honk when I passed your bus stop yesterday while driving my 944? I wonder what MOST of the folks on line thought! I could picture it: "That was for me - he's one of those crazy Porsche owners I told you about!"

Brian P

Yep. I waved back, but I think you didn't see it.