Les Davis wrote:
Richard, my only response to you would be that assuming your driving a modern car with airbags, the factory seatbelt and front airbag are working together to do their best to keep your head from those hard objects. Obviously they are not perfect, hence the advent of side curtain airbags, but it is their intent. The seatbelt and airbag do nothing to keep you from going backwards and up in the event of a rear end collision when your seat back breaks, in fact they may exacerbate the situation. A convertible may well be a more safe car in this situation assuming your car does have side curtain airbags, unless of course the openness facilitates your head coming in contact with some portion of the vehicle that is t-boneing you. I think if your going to drive any car on the street with a rollbar, convertible or not, you should have a seat brace like VK has in his Z24.
Les, I pretty much agree if you limit the discussion to modern cars. I think that since most tests are for front impact, that you are less likely to hit something like the "B" pillar or door frame except for maybe some type of rebound action. And with really modern cars that have side impact air bags, they are really trying to solve the issues I mention. I think if you watch the "before and after" crash tests for side impact air bags (heads hitting everything from door frames to the hood/grill of the car that hits you) you can see that the issues I mention existed, but they just didn't want to talk about them until they had a solution (side impact air bags)
But I am also curious how this fits in with much older cars. My 914 has a built in roll hoop and it is pretty much in the same location that a roll bar would be if it was a closed top vehical. Not directly behind my head, but close enough that I think I could hit it in certain scenarios. I am pretty sure that any existing padding is cosmetic in nature and more to prevent bumped heads during normal entry/exit vs. crashes. I am also guessing that the safety regulations from this time period only include frontal crash testing. My 1972 model does not even have any side impact beams in the doors (came just a year or two later in the 914) and the pre 5 MPH bumpers use 3/4 rubber to cusion impacts (later models had gas cushioning in the bumpers). This is why this car weights nearly 2000 lbs stock. So I am wondering if a full cage + padding in my 914 might actually be a safety improvement even if not wearing a helmet?
For background purposes, my 914 is going to be a 90% track/autocross car, but will be street legal as I will be driving it to/from events and maybe infrequently on the street on nice summer days. I also have to mention that in the late 1980's I totalled a 914 in a severe front and side impact crash and walked away with just bruises from the seat belts.
Vincent Keene wrote:
Also one could argue that all the goverment tests seemed to be geared toward fornt end and finally now side impact collisions. I don't thing the rear end is high on the list, though IMO it should be.
I actually think that rear impact has been on the list and has been looked at a lot recently. However I think mostly from the point of view of the seat and the location and design of the headrest. Apparently headrest design has a huge impact on how much head and neck injury you will receive in a rear in collision. I think the side impact stuff is the new kid on the block. Sometimes I wonder if the head/headrest interaction is different with a helmet on.
_________________
Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.comMoney can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.
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