BKAuto

I'm not familiar with tire standards. It's possible there are specific features the DOT requires that the Yokahoma does not have, even though it may be a perfectly safe tire but that's speculation on my part.

As far as our end, the formal testing is obviously to confirm that our parts are safe, as well as to back up our claims. The DOT does not interact with us, we only have their regulation books to conform to. However they or another party could challenge our claims if they felt it was necessary, which is why we have records to back it up.

TT Gasman

So here is what I have learned from this discussion as pertains to my street/DE 996 coupe. I have a couple of options, leave the car in the stock, factory configuration (stock seats, 3 point belts). Or install a DAS roll bar that will bolt in for track use only along with 5 point harnesses. How about a roll bar with the stock 3 point belts? TIA

Chris Y.

Doug...

There is some debate about running a roll bar with stock seats since they have a greater chance of collapsing backwards in the event of an accident and the possible contact with your head and the bar. Do you have seats (ie. GT3, Recaro, etc)?

I was just at a body shop looking at a brand new E55 that went off a mountain pass and was suprised to see how far the seat flexed backwards. Some say it's a safety feature to move the occupant away from the roof, but I don't buy it.

RedlineMan

Chris;

I think you are missing a key point on the seats. Actually, stock seats are far safer than many race seats in my opinion.

There are a lot of flimsy plastic seats available out there. Most of them are absolute junk. The best of them are F.I.A. rated. These seats have been tested and certified to be tough enough to meet F.I.A. specs for durability.



A seat SHOULD flex. Not to move the driver, but absorb impact and dissipate energy so that the DRIVER does not have to absorb it. Mercedes is quite aware of this, I'm sure, and what you saw in that seat was at least to some degree intentional.

See the concurrent roll Bar thread for more details on this stuff.

Chris Y.

Thanks for the info John...

Maybe I'm mistaken, but aren't reclinable seats more dangerous than say a GT3 seat that is FIA approved...? A seat should flex and there is some flex to the GT3 seats, but not backwards to the point where the driver could make contact with the roll bar, correct?

I guess it goes back to the debate about roll bars in a street driven car without a helmet...

Back to DJ 996's question...Should a car with a roll bar & stock 3pt belts be driven on the street? Does a person with this configuration (roll bar & 3pt stock harness) risk hitting his head on the roll bar if the seat moves or flexes backwards?

boqueron

quote:
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I have a couple of options, leave the car in the stock, factory configuration (stock seats, 3 point belts). Or install a DAS roll bar that will bolt in for track use only along with 5 point harnesses
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It seems that the your safest second option should be a Roll Bar and a 6 ( not 5 ) point harness. Here the technical support:

http://www.opentracking.com/5_pts_vs_6_pts.htm

RedlineMan

Chris -

IF an articulated seat will flex more than you would like vis-a-vis your roll over protection, then it becomes a problem. That is one of the many gripes I have with most bolt in roll bar solutions available.

For a street car, we have different needs. The tubing should be placed far enough away from the driver to minimize the liklihood of contact. Since none of us are wearing helmets, that means farther away than many designers are thinking. For instance, my 944 roll bar is pretty far away from the average driver for that reason, among others. If you have tubing surrounding you in your street car, you are posing a risk to yourself that you should perhaps reconsider, and this one area where a harness bar has a distinct advantage.



There is one area in racing where acceleration is the enemy. That is in tube placement. If there is no opportunity to place tubing where the driver could never contact it, then put it close enough - and PROPERLY padded - that the dangers that bodily acceleration pose are minimized. (Please note the Kirkey High Density padding and tube placement in the 930S I built below)



In a race car where the driver will be fully kitted at all times, It is best to put the tubing in a closer proximity to the driver than one might think if there is no oppportunity to get it far away. In other words, put it close so that any body part will not have the time/space to accelerate and increase the impact to this tube(s). Proper high density padding is also again essential.

Boqueron -

Thanks for the link. Very interesting. However, I am not sure I agree with one part of it. I may be wrong, and I do not have any test data to back up my claims, but my gut says that they are missapplying some of their thinking.

Regarding sub straps - In a formula car where the driver is in a nearly prone position, the sub strap is indeed intended to keep the driver from sliding under - or submarining - the lap belt. For our purposes, sedan drivers sit so far upright that this will likely never be the case. In that instance, a sub strap's job shifts to become one of keeping the lap belt in a low position on the hips when an impact occurs.

When you hit something - or even tighten your belts - without a sub strap, the shoulder straps will pull the lap belt up over your stomach. The sub strap is what keeps this from happening, not allowing the lap belt to rise above a proper height on the hips.

They contend that the substrap is actually doing at least part of the direct job of holding the occupants back in the seat during an impact. Why then do we have lap belts, and what is their purpose? If this were the case, then we would have shoulder straps that continued down and under your butt, and mounting somewhere behind the driver on the floor. Turning into essentially a cradle.

Since a sub strap is only 2", and is not readily adjustable for tension, I feel that to say that it is directly responsible for holding a driver in place IN A SEDAN is a bit erroneous. I therefore contend that to say it helps "tighten up the main belts more quickly" is also slightly erroneous. Since it is not physically possible to tighten a sub strap nearly as tight as the lap belt, how can it tighten up something that is tighter than it?

If the driver's hips were to rotate forward and begin to move under the lap belt, then the sub would indeed be called upon. If the substrap DID tighten up a lap belt and directly hold a drive in place, I would say that this is proof that the lap belt was not properly adjusted in concert with the substrap in the first place!

To the extent that my assertions are true, I also question their thought that one type of sub is better than another. IF the sub were utilized as a direct means of holding the driver in place, then the use of a 6pt sub has definite benefits that are obvious to any male out there . However, if the lap belt is utilized properly, and keeps the hips from diving and rolling forward, I contend the type of sub is irrelevant.

I know this seems like splitting hairs, but I feel this is yet again another in a long line of ideas derived from open wheel racing that do not transfer directly to sedan use without careful revision to match our environment.

I also know that most people using a sub strap need to rethink how far down it pulls the lap belt between the legs. It is indeed a pain to have the thing V-down so far, but if you notice, when you tighten those shoulder straps, the lap belt will rise right up into position... and stay there!

Whew... long winded SOB, eh? . This stuff gets deep, but it is also important. A good discussion!

Chris Y.

John...

Very well said!!! I agree with all your statements!!!

Safety discussions will and should never end!!! A life long learning process!!!

Chris Y.

John...

Question about roll bar padding...What are you thoughts about the padding, even high density padding? Some safety experts say all it's good for is soaking up the blood after an accident

TIA.

Steve in FL

Chris Y: It sounds like you and I read the same article on safety padding. The impression I got was the high density padding _is_ recommended while the old round foam stuff is what was referred to as "only good for soaking up the blood after an accident." Perhaps you read that differently?

Chris Y.

Steve...

I believe you are referring to this one: http://corner-carvers.com/wiki/index...afety%20Issues

Yes...he talks about the SFI approved one being the one to use. But I've spoken to other safety experts and the local PCA guy who does the safety checks at track days and he doesn't believe in an accident, 3" of padding (even SFI approved) can do much without a helmet.

My take: I'll probably re-do my bar with the SFI stuff...better than nothing?

Steve in FL

Chris: Yes, same article. And yes, the SFI stuff should be better than nothing. I had lost track of the thread topic and was thinking in regards to helmet vs. padding on the track rather than head vs. padding in a street accident. I think SFI approved would be better in either case.

RedlineMan

Hey guys;

As it seems I recall someone mentioning, do your own test. Smack a tube protected with generic padding with your fist, or better, your forearm. Then try it with the high density variety. Both will hurt, but you will quickly note that the generic allows your bones to sink to the tube, which as you might imagine doesn't give too much!

I did this some time ago, and the results were obvious. I've used nothing but the high density stuff in my creations for some time now. This would likely not keep you from getting a concussion without a helmet on, but it might just prevent a more serious closed head injury, or a fractured skull! With a helmet on, the decrease in shock to the brain might be fairly significant.

smokey

Given that harness bars plus shoulder harnesses without harness slots are permissible only in PCA DE, I have to ask whether there has been any crash testing or engineering analysis of this combination, and whether there are any minimum standards for harness bars - or just opinions. I also track with the BMW Club, and they will not permit harnesses without a roll bar and a seat with harness slots. Harness bars should be able to withstand the same G-loads from the driver and passenger shoulder harnesses in a collision as the OE shoulder belt mounting bolts . On the basis of a visual inspection, there are harness bars out there that do not meet this criterion, and the occupants would be safer with the OE three-point belts.

RedlineMan

I agree, Smokey;

I have heard that there is some test data that shows that in some citcumstances the belts will not stay on a driver's shoulders without a race seat or other belt locating device.

I agree that the criteria for harness bars has been a joke. My minimum standard is roll cage spec tubing, period.

The problem to me really boils down to how much encumbrence you can place on the participants? There is a line between being safe and making it too much of a hastle. Each person has to make their own decision regarding how much they are willing to put up with. Perhaps the real fault of organizers is not making people aware of the consequences so that more stringent requirements seem more palatable?

I'm not sure where I stand yet, but the cars are getting so damn fast and capable that I'm afraid more "draconian" rules will be necessary!