Lightening doors in S classes

Discussion related to classification of cars in the NEHA series.

Lightening doors in S classes

Postby Chief Geek » Tue Jan 21, 2014 2:02 pm

The 2013 classification rules for S classes say
intrusion bar, outer framework and basic structure of the door must remain intact.

My hope was to "hollow out" the drivers door to make room for roll cage door bars with as much crumple room as possible. Running the door bars right behind the exterior door skin also makes entry and egress much easier.

What do the safety and technical experts think about changing this:
Doors may not have any structure removed causing them to be excessively lightened – i.e.; intrusion bar, outer framework and basic structure of the door must remain intact.


to something like this?:
Doors may not have any structure removed causing them to be excessively lightened – i.e.; intrusion bar, outer framework and basic structure of the door must remain intact unless the car has a cage that meets section E of the Technical Regulations.


Paul
"Christina", New #13/#55x, '90 Miata: In progress
"Keiko", Old #13x/#55x, '96 Miata: R.I.P.
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Re: Lightening doors in S classes

Postby walterclark » Tue Jan 21, 2014 6:19 pm

I havent seen a side intrusion bar that was positioned anywhere but at the outer skin of the door,. Cage door bars dont need to project out to the outer door skin to be effective and having both improves side impact energy absorption, so I dont see a reason to remove them other than to reduce weight. The current wording does not preclude cutting the inner door skin and door panel back for clearance of extended door bars so long as the basic structure (frame, hinges, latch) of the door remains.

That said, in many cars some added fabrication will be needed to retain a stock side window (albeit with less to no travel) since most of the window attachment hardware bolts to the inner skin and the door bar is probably going to intrude into the area of the side window and tracks when lowered. Removing the inner door skin, and side window entirely or replacing the window with a fixed polycarbonate window, is excessive lightening under our present rules and I think that should remain to discourage rule playing... 'I gutted the door and put in a fixed poly window to make the car safer so I didnt include excessive lightening on my class determination worksheet.' I am paraphrasing an actual situation and comment from a competitor.
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Re: Lightening doors in S classes

Postby Chief Geek » Wed Jan 22, 2014 1:34 pm

Walter

Totally fair points. Part of the reason I want my door bars to project into the door as far as possible is that it make ingress/egress much easier. There's no doubt I'm going to have fixed windows and will certainly earn the "excessive lightening" penalty.

My goals were to save space and weight. The Miata's OEM intrusion bar is right where I'd like to put a cage tube and it's deep enough to make dodging around it a pain. Also the OEM intrusion bar constitutes about 50% of the doors weight. My plan was to keep the door's exterior skin, hinges, OEM latch, and most of the perimeter frame. The exterior door handle would stay, but the interior latch release will probably be a piece of cord or cable. Don't know about the door lock yet.

Let me know what you think.

Paul
"Christina", New #13/#55x, '90 Miata: In progress
"Keiko", Old #13x/#55x, '96 Miata: R.I.P.
Daily Driver: '11 Mazda2 (small cars... some men have nothing to compensate for)
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