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OG racing cage for club racing

 
Old 03-09-2005, 08:39 PM
  #16  
Matt Marks
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Wormhole,

FYI - NASA will take a PCA club race license - double check with them, but all you should need to do is join NASA for a year's membership ($45?) and they'll issue you a temp NASA license - which you can probably convert to a full license by providing a current medical.

I gave them my PCA club race medical which was 6 months old at the time, and they took it with no hassles.
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Old 03-09-2005, 10:26 PM
  #17  
richard glickel.
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John,

Where are you in N.Y.? You may wish to check out John Hajny's website. He is most knowledgeable in setting up track cars and is a masterful safety cage fabricator. Located near Binghamton.

Richard
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Old 03-10-2005, 10:02 AM
  #18  
RedlineMan
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Originally Posted by Bill L Seifert
John, when you said door bars are only as good as to what they are attached to, were you speaking about Kirk Cages? Or were you just speaking in general? I have a Kirk, is there something I need to know?
Bill -

I don't know anything specific about Kirk cages for 944s. I did install one of their "bolt in" roll bars in a C5 Corvette. I was not overly impressed!

I have a 944T in the shop right now that has some brand of bolt in cage. Not an OG. Might be an Autopower. Anyway, it bolts too the floor, which is enough to turn me off right away. So, the front pad is bolted to flimsy sheetmetal, the side hoop is coming down in front of the dash (right about knee level), and the door bar comes forward from the rear hoop.

What do you think would happen if there was a significant enough intrusion to smack that door bar pretty hard? It would rip that hoop mount out of the floor like tissue paper and mash the entire side structure into your legs, pinning them against the center tunnel. I envision two severely crushed legs.

I see the door bar in such a case being FAR more dangerous than having nothing. There are a few other critical aspects of door bars that no one thinks of as well.

The ghost lines represent the old setup, and then there's my solution...


http://www.redlinerennsport.com/BSlowBuildup.html
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Old 03-10-2005, 10:33 AM
  #19  
Bill L Seifert
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John, Ok I see. My old cage is bolt in, as it was done by Kirk in 1992. My new car, is also a Kirk cage but it is be a weld in. Also the NASCAR bars cross just below the middle of the door. Looks good to me, but I am sure not an engineeer. Is soon as I can figure out how to send a picture with this new digital camera, I'll post it.

Bill
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Old 03-10-2005, 02:29 PM
  #20  
Wormhole
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Well, I was looking to really budget on the cage. Yes, my noggin isnít worth much , but I must admit that cage looks very tempting.
John, Iíll hit you up for a quote. I have your roll bar, and luckily I havenít tested it yet, but I always did like the design.
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Old 03-12-2005, 09:14 AM
  #21  
RedlineMan
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Bill;

Speaking of "NASCAR bars," That term refers to THIS type of door protection scheme...



Door bars that protrude out into the open cavity in the door allow easier ingress/egress, and seemingly would be quite strong because of the nature of an "arch" structure. Some shops "replicate" the idea behind NASCAR bars... in theory. In fact, they are not necessarily a very good idea if not done to NASCAR extremes.



NASCAR door bars are strong because of the shear mass and quantity of the tubing, and the fact that they have extensive "vertical webbing" tying them all into eachother as WELL as the frame rails at the base. The version above does not quite replicate those characteristics.

The first things I look at are: where are the end of the door bars, and how sturdy is that point. This one seems to have side hoops welded to the floor. Not so hot, if so. The second thing I see is that there is a knee tube to send the intrusion load across the chassis, spreading it out. Although this adds some points of unrelated danger, in terms of side intrusion it is a Good Idea! The next thing I see is that the door bars attach no where but at the ends. They DID NOT take advantage of tying into the side sill, which is a glaring omission to my mind. Here's why.

An arch is strong until it fails... of course. In the case of door bars, when the arch structure does give way, it then becomes an elastic piece. It's length then becomes a liability. It will continue to bend in relatively easily until its length is exceeded, at which time it acts as a "strap" and pulls against its mounts; the side and main roll hoops. The greater the arch in this tube, the farther in it will intrude before taking up slack and pulling against its mounts. If THEY are not strong, they will be pulled along as the whole thing keeps collapsing.



The "X" type door bar like in the Cup Car are inherently strong because they are "straps" by design. They pull against there mounts immediately, and start transfering load right away. An arched door bar scheme like the red car will not do this. It will also not nearly meet the safety levels of the NASCAR setup because it lacks the extensive tubing network that creates an extremely strong complex beam structure that is tied at NUMEROUS points.

The red car's setup isn't all bad, but it could be better. An arched tube door bar CAN be made strong, but there's more to it than just throwing tubes in the doorway.

Whew... too much time on my hands this morning!
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Old 03-12-2005, 10:24 AM
  #22  
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I've had a real education in cages this winter. Like most things, you get what you pay for. I had a bolt in roll bar in the car which undoubtedly presented more of a hazard then a safety item. A good cage does more than protect you, it stiffens the car as well and really can be significant performance item, at least in an old tub like mine.

For the doors we went with the rally style X brace, but put a curve in the top tube to add a little elbow room. Heres pic, more available at http://mysite.verizon.net/rj.mann/id35.html
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