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Thread: Roll Bar question

                  
   
  1. #1

    Roll Bar question

    Well the project car made its first successful track debut last weekend at Summit main for the NCC BMW CCA 2 day driving school. Performed like a champ.

    BUT the wife has laid down the law. If I wanna keep playing race car driver (which I do) then I have to install a roll bar. She would rather have me than the Insurance dough - go figure . . .

    And so I am researching the I/O Port Racing site and also Kirk Racing to see about a 4 point roll bar kit that I can purchase, have shipped to MD, weld in, and that will also expand to full cage when I am ready.

    Any buying tips, suggestions, places to purchase that come to mind?

    Thanks

    John
    John Rock

    follow the E30 track car build . . .
    http://www.cardomain.com/ride/2681791

  2. #2
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    Roll Bar and Safety

    The following discussion appeared in der Bayerische, Jan-Feb 2006. It's not directly responsive to the question but it is thought-provoking.

    Roll Bar Safety Discussion

    A frequently asked question from drivers’ school enthusiasts:

    “I've done several HPDE (high performance drivers’ education) events and I'm planning to do a lot more. I drive an E36 coupe, which I'm told does not provide much rollover protection. Should I install a roll bar?”

    David Bryan responds:

    The easy answer is, "Yes, put a roll bar in." It will certainly improve your safety in a rollover.

    The more complex answer is, "There are a number of factors that affect your overall safety, and some thought should be given to the order of their implementation." For example, a roll bar will only improve your safety in a rollover, whereas street tires will improve your safety not only in rollovers but also in frontal and side impacts (by reducing the energies of those impacts). The energy to deform the roof is a function of the square of speed, so reducing cornering speeds from, say, 85 MPH to 75 MPH reduces the potential impact energy by about 30%. Indeed, this is a significant reason as to why I am safer when driving in the rain: any impact will be substantially less devastating.

    Also, the attachment of the bar is just as significant. Will the attachments yield? I've seen bars held in essentially by screws into sheetmetal. Not a prayer of staying upright in an impact, and so the bar itself might become a hazard. A bar in a street car poses a risk to an unhelmeted driver and passenger in case of an impact on the street. Even a padded roll bar can give you a headache or worse when you are rear-ended on the street.

    Do you employ the best helmet you can afford? Are you using one with a Snell SA-2005 rating? Are you leaving enough margin for error in your driving? Impacts aren't acausal; they result from drivers' errors exceeding the margins that they left for error. Is your tech mechanic really going over the car carefully with an eye to the stresses involved, or is he simply doing a standard service check? I've seen impacts "caused" by brake problems, cooling problems, belt problems, etc.

    On the other hand, one thing that will significantly increase your danger is to employ four-point harnesses without a roll bar. When the roof crushes flat, the only means of survival is to be pushed out of your seat belt; if you're held rigidly upright, your neck is going to be snapped. [comment by Roy Morris: With a CG Lock fitted, stock seat belts can provide most of the holding power of a harness while still allowing upper body movement when you need it.]

    So there's not one easy answer. The worst thing a driver can do is to believe that "if you do this long enough, a crash is inevitable." It is NOT! You can quite drastically alter the likelihood of an impact by the approach you take to driving.

    So my first safety recommendation is to stay on street tires until your skidpad score is above 3.5. Do that, and your safety probably will improve about three to one. And while the general thinking is that everyone "needs" to be on track tires, consider that several of our instructor-candidates stay on street tires until their car-control skills catch up with their potential speeds on the track. Going onto track tires early means that, in extremity, you need to have half-second reaction times, but you have developed only three-quarter second reactions. Take your time, and allow your skills to improve. Safety is not something you just buy and install.

  3. #3
    Thanks for the reply.

    You're right thought provoking. And since I am still on "street tires" I can see the benefits of staying on them for some time.....
    John Rock

    follow the E30 track car build . . .
    http://www.cardomain.com/ride/2681791

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