As promised, Bob "Speedy" Nevins' take on the deal, reprint authorized by Bob. bp
TIRE SHAKE +
I think Barry and I discussed this years ago about the different outlook on roll bars/padding between the NHRA and SCCA. Having done both for years and over on my head a couple of times, I have to say that I disagree with the whole NHRA/SFI theory. Think of a Bell. What makes it ring? The clangor/ball, that swings from side to side and strikes the outer bell shell, thus setting off a strong vibration. In SCCA road racing the driver's head is kept clear of all hard roll bars etc. He is protected by them but not subject to banging his head against them. This has nothing to do with a Hanes/neck collar/helmet restraint system. That is a good thing, for all the right reasons. Strong monocoque aluminum seats with padding and high backs and sides (like I had in my both my Willys) add safety. The six way driver's belts and arm restraints all pull the driver down to the chassis vibrations, and allow him to be a "Tuning fork", transmitting the cars vibrations. I know most of you guys have not had the experience of the tremendous/violent G forces generated by a blown fuel car. The extreme violent tire shake is part of it. I fought with it in my old fuel funny car and never really cured it. We just raised the tire pressure a bit so at a certain point the tires would break loose instead of running square and shaking.
I will share with you one of my "features" in my Safety/Econo car that I designed. I designed a "Tilt" type device, mercury switched master cut off switch. So in the event of a roll over,(anything more than 45 degrees), it cuts the power/kills the motor and prevents fires/shorts. A circuit breaker/fuse in an electrical system, disconnects the power when a abnormal surge occurs. What not a "Vibration Circuit Breaker"? At a preset level of it would just shut the power down. This would force the crew chiefs to tune the cars so that they launch smoother or blow-off the tires in smoke. 8,000+ horse power and 5 lbs. air pressure in flat-bottomed sticky slicks says, something has to give or shake sooner or later.
Back to the NHRA/SFI roll bars/padding...Have the same spec cage but move it slightly away from driver contact. Another one of my safety features in my Econo/Safety car is the removal of hardware. In a street car accident, what hurts the people inside? Banging around on window cranks, door handles, rear view mirror, etc. My car uses good old Velcro to raise and lower the shatter-proof Mylar side windows (like the old MG sports cars). Can't break you arm against something if it isn't there to hurt you. KISS
Yes, there is a need for improved, thicker/energy absorbing seats and helmets. Also maybe just cut the power/size/speed of all the Pro cars and take 90% of the risk factor out of the equation. KISS "Speedy" On the soap box again. LOL