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Cage design in an open car?


Grant

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By "open" I mean one without a windshield, windshield frame, or roof. I didn't see anything regarding this in the CCR or the PT/ST rules, except: "removal of the front windshield/windshield frame +7".

 

Our cage builder is following NASA rules, but there is a snag: much of the rules talk about bars following the roofline or the A-pillars. We have neither. We were going to set the main hoop 2" above the helmet of our tallest driver, set the halo high enough not to get in the way of anyone's vision, and run the down tubes roughly where the A-pillars would be.

 

The long story:

 

Some friends and I are building a LeMons/ChumpCar. After spending untold hours cleaning Dynamat out of it (way more time than should be allocated to a LeMon!) we are thinking we will run it in a more serious series if it survives its first enduro. The car had a tree smash in an A-pillar and part of the roof, so we sawzalled it off (like you see with a good number of LeMons entries). We are about to start the cage and wanted to make sure it would be NASA legal.

 

The SCCA has rules specifically for cars like this. Their only added restriction seems to be "the top of the main hoop must be at least 2 inches above the driver's helmet". They also allow for asymmetrical main hoops as well as "low" front hoops (what you'd see on an EP Miata, for example), but I'm guessing these would not be NASA legal.

 

Another thread on the topic is here:

viewtopic.php?f=18&t=13953&hilit=cage+convertible

(though David looks like he's keeping the windshield frame)

 

Thanks for any help.

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It is actually easier to put a cage in an open car than one with a roof. Make sure you give yourself plenty of headroom and you might want to consider an "aero" helmet with the lip - or you'll look like a bobble-head at speed without one!

 

cage.jpg

 

We built a Camaro that was slated to run in LeMons but decided that the car was too nice to suffer all of the contact that occurs in those races. We ran it in the Santa's Toy Run 9 Hr Enduro last year and had a blast! Same amount of fun and less expensive!

 

tn_20091207%20250.jpg

 

-Jim

http://www.WildHorsesRacing.com

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Jim, thanks for the suggestion. I didn't know about the Santa Toy Run Enduro, that sounds like a great idea. I'll just need to convince my other teammates of it.

 

Ken, thanks I'll point some of the NASA SE guys to this thread.

 

This is a symmetric/asymmetric main hoop:

mainhoop.png

The light gray bar would be a symmetric main hoop, while the darker one would be an asymmetric hoop. The SCCA allows both in open cars. I am guessing the hoop needs to be symmetric in NASA, due to the language "the main roll cage hoop should be as wide as the full width of the interior", but I'm not 100% sure because the asymmetric hoop is full-width, just not in the upper area. We would like to run an asymmetric hoop if it is legal.

 

This pic shows the "low front hoop" option the SCCA allows:

mainhoop2.png

The idea seems to be to lower the halo down above the dash. To me this might legal under 15.6.10 Front Hoop (Option 3), but its hard to say since we don't have a windshield, roof or A-pillar. The big plus for us here would be easier driver changes (as the driver has to climb out of the car).

 

This illustrates how high we'd make the main hoop, and what our cage would look like with a symmetric main hoop and normal-height front hoops.

fullcage.png

I am guessing this would be NASA legal and is the sort of cage we'll end up with, though I still don't know if there is any restriction on the height of the front hoops.

 

Our ideal cage would be what you'd find in an SCCA Production convertible car:

AboveFrontFull2.jpg

 

Thanks for any help.

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