[PeterAllen]

Zedn - I agree with what you are saying but I think you are talking about a best case impact scenario. If I'm in the position of starting to fit the intrusion bars I would like to think I could design for the worst case scenario and work down based on the limitations I encounter.

After reading John Wilson's newsletter I understood I should ensure the intrusion bar does not inhibit the ability of the door and hinges to hold the door in place in an impact. However, when I spoke to someone at the Transport Dept today they were telling me to attach it to the hinge and the door latch. Am I reading John's newsletter correctly? - I'll check the actual ADR later.

I don't want to be morbid about this but did anyone see the Daytona after Brock's crash, or any Cobra with a pole side intrusion, to see if the hinge and/or latch were torn from the fibreglass door. I'm not disputing the strength of the bolts; I'm just trying to understand the weakest point in the whole door structure. Does fibreglass act as a good impact attenuator or does it tend to shatter?

You are correct that the occupant of any severe impact will experience hyperflection of the neck in the direction of the impact and that's why most race cars have halo head rest and those neck thingo attached to their helmets and held in place by the seat belt. Since the introduction of headrest the term 'whiplash' seems to have disappeared in relation to rear impacts - all a little off the topic of intrusion bars.