Safety Equipment
06-10-2005, 01:47 PM
#46
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Originally Posted by kurt M
(Caution one persons opinion mixed with some facts to follow)
The Boxster bar and seat are designed to work together and rearward movement is limited by the firewall as it also is in a 914. Watch a video of a rear end impact and you will be stunned at how stock and many race seats flex and or fail. As the seat is failing and the car is moving forward the occupant is not and impacts into anything that is behind them. The seat is also only as good as the mount. Race seats mounted on the little stock bolts and sliders are not much if any better than stock with regards to a full on failure.
Soft roll bar padding is worthless for anything other than nuisance head dings while crawling around in the car. Period. The hard SFI stuff is the material to use but it only works with helmets not naked head. Roll bars are unsafe for heads. The shape of round pipes is very good at cracking skulls compared to flat surfaces. G for G hitting you head on a pipe will cause more damage than say, the side glass. If Elly May is going to hit me on the head for coming home late and drunk, make it the frying pan and not the pump handle.
The roll bar will add safety when you are on the track. The majority of this is coming from it being a great place to attach harnesses. On the street given the unlikelihood of a roof crushing impact but the far more prevalent chance of a mid to high G impact without intrusion the roll bar will not truly add to your protection unless you are in yotr 5 or 6 point system and are protected from hitting it. The down side being that most stock seats are not enough protection.
The Boxster bar and seat are designed to work together and rearward movement is limited by the firewall as it also is in a 914. Watch a video of a rear end impact and you will be stunned at how stock and many race seats flex and or fail. As the seat is failing and the car is moving forward the occupant is not and impacts into anything that is behind them. The seat is also only as good as the mount. Race seats mounted on the little stock bolts and sliders are not much if any better than stock with regards to a full on failure.
Soft roll bar padding is worthless for anything other than nuisance head dings while crawling around in the car. Period. The hard SFI stuff is the material to use but it only works with helmets not naked head. Roll bars are unsafe for heads. The shape of round pipes is very good at cracking skulls compared to flat surfaces. G for G hitting you head on a pipe will cause more damage than say, the side glass. If Elly May is going to hit me on the head for coming home late and drunk, make it the frying pan and not the pump handle.
The roll bar will add safety when you are on the track. The majority of this is coming from it being a great place to attach harnesses. On the street given the unlikelihood of a roof crushing impact but the far more prevalent chance of a mid to high G impact without intrusion the roll bar will not truly add to your protection unless you are in yotr 5 or 6 point system and are protected from hitting it. The down side being that most stock seats are not enough protection.
06-10-2005, 03:31 PM
#47
Nordschleife Master
Jeeva,
When I bought my BK harness brackets, there was only one size tunnel side bracket. Now they have 2, the standard and the short. Which one do you have? Just wondering if I need to get something different for the GT3 seats.
When I bought my BK harness brackets, there was only one size tunnel side bracket. Now they have 2, the standard and the short. Which one do you have? Just wondering if I need to get something different for the GT3 seats.
06-10-2005, 03:38 PM
#48
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Originally Posted by Palting
Jeeva,
When I bought my BK harness brackets, there was only one size tunnel side bracket. Now they have 2, the standard and the short. Which one do you have? Just wondering if I need to get something different for the GT3 seats.
When I bought my BK harness brackets, there was only one size tunnel side bracket. Now they have 2, the standard and the short. Which one do you have? Just wondering if I need to get something different for the GT3 seats.
I did'nt know there were two different sizes, so I don't know which one I have,...unless you can tell from the pictures. You may want to call Austin at Devek, he will know...I know my mechanic had no problems with the set-up, except for the sub-belt mounting on the porsche tequipment sub-belt bar.
Jeeva
06-10-2005, 03:45 PM
#49
Mr. Excitement
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Originally Posted by karlooz
so then you are saying boxster owners are guaranteed a nasty head injury since the roll bar is quite a bit closer than the roll bar in my 996
06-10-2005, 04:00 PM
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Karlooz, No Kurt is not saying that the boxter owners are in peril of having there heads opened up on a rear collision, to the contrary, he is saying the firewall will act as the seat brace and will prevent you from hitting the roll bar.
how ever, Kurt your statement that "Race seats mounted on the little stock bolts and sliders are not much if any better than stock with regards to a full on failure.", proves my point, that is if you agree that these stock seats are tested to not break-off in a rear collision, otherwise we are all in trouble with or without roll bars. How safe would one be if their seats are breaking off the sliders irrelevent of the roll bar. So, we can assume that it is rare for the seat to break off. Now THIS DOES NOT MEAN THAT THEY DON'T FLEX, INFACT THE FLEXING IS PART OF THE SAFETY FEATURE, AND THEY FLEX EVEN ON MODERATE COLLISIONS. But if it does not come off of the slider, the seat will describe an arc flexing back, and the harness WILL stretch to pull your head up, so if you are a few inches away from the bar, you are certain to hit the bar, but if you are more than a foot away, it's unlikely. (I just measured it, it's about 11 to 12 inches away)
Dave,S. Placing a back brace is not full proof either, as the seats in our cars are designed to flex to absorb the impact, and preventing it could in theory pass all that impact on to you the passenger, and all those organs floating inside. So, there is always compromises, I'll take my chances with my set up, and as I am 5'10" there is no way for my head to hit the bar, unless the seat breaks off...but if the collision was severe enough to un-bolt the seat, what are my chances with or without the bar. How ever, I am a hell of a lot safer at the track with my set up.
Jeeva
edit: Kurt, I did'nt see your post when i started pecking away at the key board.
how ever, Kurt your statement that "Race seats mounted on the little stock bolts and sliders are not much if any better than stock with regards to a full on failure.", proves my point, that is if you agree that these stock seats are tested to not break-off in a rear collision, otherwise we are all in trouble with or without roll bars. How safe would one be if their seats are breaking off the sliders irrelevent of the roll bar. So, we can assume that it is rare for the seat to break off. Now THIS DOES NOT MEAN THAT THEY DON'T FLEX, INFACT THE FLEXING IS PART OF THE SAFETY FEATURE, AND THEY FLEX EVEN ON MODERATE COLLISIONS. But if it does not come off of the slider, the seat will describe an arc flexing back, and the harness WILL stretch to pull your head up, so if you are a few inches away from the bar, you are certain to hit the bar, but if you are more than a foot away, it's unlikely. (I just measured it, it's about 11 to 12 inches away)
Dave,S. Placing a back brace is not full proof either, as the seats in our cars are designed to flex to absorb the impact, and preventing it could in theory pass all that impact on to you the passenger, and all those organs floating inside. So, there is always compromises, I'll take my chances with my set up, and as I am 5'10" there is no way for my head to hit the bar, unless the seat breaks off...but if the collision was severe enough to un-bolt the seat, what are my chances with or without the bar. How ever, I am a hell of a lot safer at the track with my set up.
Jeeva
edit: Kurt, I did'nt see your post when i started pecking away at the key board.
Last edited by Sanjeevan; 06-10-2005 at 11:21 PM.
06-10-2005, 04:04 PM
#51
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Originally Posted by kurt M
Quite the opposite. In you car when the seat fails you will spill out backwards with nothing to stop you as you migrate into the back seat area. With the Boxster you hit the firewall BEFORE you spill out of the seat. This is not a case of distance is better. It is the spilling out part that is the problem. When this happens the head rest is no longer there to be between your head and the bar. The base of the seat remains planted and your head moves back/ up and away from the headrest. Bear in mind that this is a hard *** hit from behind and not a “oops” fender bender type event being discussed.
sorry, your theory is not convincing me. if the seat fails in a boxster the first thing that the seat back hits is the cross bar of the roll hoops not the firewall. then when your body spills out the first thing that would hit the hoops is your head.
try reclining the seat of boxster all the way back (without sliding the seat back) and you will see what i mean. i did it in my old boxster just for giggles and it was eyeopeing. since then i drove with a minimal recline angle.
this all comes with a caveat, however. i sat very low so that i would have the most amount of over-head space. when i tilt the seat back all the way the head is exposed. if you bring the seat up in height then the headrest may cover the hoops, but now you would be riding real high. YMMV
going back to my car, i can use a seat back brace and minimize rearward seat deformation.
06-10-2005, 04:08 PM
#52
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Originally Posted by kurt M
Quite the opposite. In you car when the seat fails you will spill out backwards with nothing to stop you as you migrate into the back seat area. With the Boxster you hit the firewall BEFORE you spill out of the seat. This is not a case of distance is better. It is the spilling out part that is the problem. When this happens the head rest is no longer there to be between your head and the bar. The base of the seat remains planted and your head moves back/ up and away from the headrest. Bear in mind that this is a hard *** hit from behind and not a “oops” fender bender type event being discussed.
06-13-2005, 09:23 AM
#53
Mr. Excitement
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This is why short answers to complex issues are not advised. I only posted here to clarify an off line discussions that was being commented on in this thread. Clarity was not achieved. Sorry for stirring the pot.
The spilling I was talking about is rearward and from the previously mentioned seat deformation. When the seat moves during an impact you are not held in as well as if it did not. You do not want your torso to flop around during a high G event. Your body can absorb tremendous peak G loading if it is not bounced around and off of things during. In order for you to sustain internal organ injury from the differential in specific gravity of organs you would need to be in a very high G or a whipping type event. So high in fact that this would be one of the lesser worries in a non whip event unless the car were built to full pro F1, or NASCAR type specs and structurally able to sustain this loading. The most likely of the S.G. type internal injuries is the brain disconnecting type and they are most often from impact during whipping and not linear deceleration. Being loose in the car would increase the chance of this type of event.
You are right, the seat can flex or fully fail and then you become loose enough to flop around and hit things. In a cab the roll bar is a truly needed and safety enhancing device that is there because there is no structural strength in the movable or hard top. The best setup is one that holds you in place and away from hard stuff
There is a lot to this and there is a good thread or two in the racing and drivers ed forum that I recommend for anyone that has further interest.
The spilling I was talking about is rearward and from the previously mentioned seat deformation. When the seat moves during an impact you are not held in as well as if it did not. You do not want your torso to flop around during a high G event. Your body can absorb tremendous peak G loading if it is not bounced around and off of things during. In order for you to sustain internal organ injury from the differential in specific gravity of organs you would need to be in a very high G or a whipping type event. So high in fact that this would be one of the lesser worries in a non whip event unless the car were built to full pro F1, or NASCAR type specs and structurally able to sustain this loading. The most likely of the S.G. type internal injuries is the brain disconnecting type and they are most often from impact during whipping and not linear deceleration. Being loose in the car would increase the chance of this type of event.
You are right, the seat can flex or fully fail and then you become loose enough to flop around and hit things. In a cab the roll bar is a truly needed and safety enhancing device that is there because there is no structural strength in the movable or hard top. The best setup is one that holds you in place and away from hard stuff
There is a lot to this and there is a good thread or two in the racing and drivers ed forum that I recommend for anyone that has further interest.
