civicrr

OK, here is a question for you. It is my understanding that the SCCA no longer requires a seat back brace if you have a seat with a FIA rating. The reason for this, is that the seat will flex & absorb some of the impact. Others have touted the benefits of Al. These seats are more rigid. They will 'bend' upon impact. Opinions, facts, info on my ideas/what I have heard.
TIA

Grumpy

Not just any FIA approved seat. Must be 8855-1999

Phoenix_ITR

iTrader: (1)

hmm...i was always under the impression that the seatback brace was required in case the seat came lose (i.e. - seat mount breaking) in a hard impact. as i understood it, the belts would hold the seat in place if you hit something going forward, and the brace would hold it if you hit something going backwards. am i totally wrong about this??

-tony

civicrr

Hmm. I also heard something like that too. If the seat base was properly mounted, wouldn't the tearing/deformation of the mounting surface absorb some energy? The brace would keep the seat from going backwards. Belts have some stretch in them which absorbs/disapates the energy from a frontal impact. Your internal organs take all of the hit going backwards with the brace.
BTW, I have a Sparco Touring seat with a IO Port Racing seat brace. The brace is still required per the NASA rules.

Tyson

i think all this confusion as to what exactly happens during an accident and why its needed or not is the root of the debate.

i actually dont know, can offer my opinions on what happens, but not sure if they help... having said that, a steel tube framed seat, if bolted in securely, is going to bend. an aluminum seat is going to flex and crack. a fiberglass seat is going to crack. whats safer, with or without a brace, with a 170lb sac of water and calcium bone being pressed up against the seat with by a stiff but stretchable harness? i cant say.

civicrr

Tyson, you are right. I guess the question should be, what is safer? Another part of the question needs to be what is the FIA test? My friends tell me that the FIA tests show less 'damage' to the driver in an approved seat without the brace.
Just want to be as safe as possible.

Track rat

I asked Brian Butler (Butler Built Racing seats) the same question a few years ago. He'll tell you that the seat back brace is an extremely important part of the seat. It is effective in stabilizing the seat in side and rear impacts. Without adequate support to prevent the seat from deforming laterally, the shoulder harness is now grabbing the side of the driver's neck as the seat flexes laterally. If the floor mounting fails, think about what the edge of the harness will do to your neck as it tries to prevent you and the seat fron ending up in the passenger side of the car. Keep in mind that his comments are relative to alum seats. Some composite seat manufacturers view it differently.


[Modified by Track rat, 1:36 PM 8/9/2002]

civicrr

OK, to add to that. Most models of Al seats (ie Butler, Kirkey) do not use shoulder bolsters. They utilize 'ribcage' support for side loads. After Ernhart's accident, I remember reading a article where a Dr. did not recommend them. A seat that supports your whole torso will offer better protection from spinal misalignment, according to the article.

Track rat

Agree. See Bulter's latest design...stout shoulder supports! Much has been learned from sled testing since #3's death.

autorex

Try http://www.fia.com/regle/REG_TEC/Normes/normes-a.htm . The first link is for the standard on competition seats. It's a word document, and the first part is in French, but it probably gives more information than most people would want to know.


Edit: Updated link since the first one I gave wasn't to the right page.


[Modified by autorex, 6:21 PM 8/10/2002]

civicrr

Thanks! No time to read it now but I definitely will.

Tyson

wow, that was a cheap bump.

Knestis

Having said all of this, I have seen some seat braces that are clearly WAY stronger than the seat that they brace. I do not like the idea of a very rigid thingie pointing at my spine, solidly attached to the cage, if the seat does fail. I have also seen some seat braces (bent aluminum sheet) that look like they provide bracing but have a provision to fail in a way that won't spear the driver. The best answer of course is a seat that won't fail - a really good FIA design w/o the brace (they are strictly proscribed by FIA regs, as I understand it) or a good aluminum seat with whatever bracing they are designed to use. Steel tube "racing seats" are still junk, I think.

Kirk