Cages, hoops and safety
I like the idea of using a sanctioning body rule as the guideline, Dave's SCORE rules are good. I am currently involved at the marque club level in exactly these issues as part of the Safety and Driving Committee - cage and hoop rules. In formulating some of the guidelines, I proposed that *any* cage/hoop design had to comply and fully pass a recognized competition sanctioning body cage or rollbar rule.
As a rule, most sanctioning bodies require a free floating cage, with a minimum (and often - maximum) of 6 mounting points with mandatory triangulation designs. The exception to that is the FIA/SCCA/NASA Rally cages that allow (mandate) triangulation of the cage to the body structure. IMO, this provides a much more realistic guideline to a offroad or street driven 80. It also allows a much tighter tolerance (even seam welding to the pillars) of the bars themselves.
I have designed and had built a couple of different competition and street/track car applications, and recommend that if anyone does this to a civilian 80, that it be done with all the glass removed. This allows a much more roomy cabin, and assures better weld quality potential.
Regarding head injury. There is a lot of technology in the latest foam protection for cages that would cause less damage than a stock A pillar or B pillar.
Hoops vs cage. My own opinion is that a hoop is better than nothing, a cage better than a hoop. The idea of the hoop is to allow a cavity to fit your head in case of a rollover. Cages are commitment, and a properly designed hoop can offer a lot of protection vs a stock truck. IIRC the DOT rollover minimum specification is 1.5 x weight for rollover. That's very little, on road or off. IIRC II, several european countries and automobiles have 2.0-2.5 factors, which gives them a really good marketing tool here.
A pillar protection. That's really tough in terms of getting a practical street design. Usually that requires a minimum of a visor brace and a knee brace, which can become a problem in a 3 point harness barca-lounger seated truck. What might be a better compromise would be a seam welded A pillar bars, and a rear hoop. Now stepping out of a 'sanctioned' rule, but certainly structurally better than stock A pillar protection.
As I've been involved in this committee and policy for less than a year, there are a lot of issues to consider in realistic application guidelines. To date, I've spent more time evaluating variance requests to the current vague guidelines the committee has established, than actually finding a good implementable compromise.
It's really tough to consider 'safety' in the context of cage in a non-competition vehicle. Looking specifically at my 80 in this mix, I would personally consider some type of half cage hoop over the front seats and rear seats as good protection. Possibly an A pillar reinforcement, but I'd take a pass on the visor/knee bar unless 5-6point belts added. Tough to sell that last part in my house....
ST
I've seen a complete job (from AU?) posted here that looked cool but not available here of course. Is a rollbar similar to the one you have difficult to fab for the front of an 80?
Baja 500 June 2007 baby!
