JR944

I agree with John entirely about the positioning of the rear diagonal bars. John's cage is also very nice in that the windshield header bar is in FRONT of the windshield header. (of course mine is positioned similarly). I've been in a lot of 944 race cars with that bar just below or behind the windshield header and IMO it's way too close to my head.

Here's my solution for a bit easier entry/egress. (I'm 5'-10', 220#) A friend ran the design through some basic FEA software and according to him we didn't lose any strength compared to the standard X design.

Good luck!

Joe

Geo

This so far has been one of the best cage threads I've seen here. Lots of good info without some of the usual holy wars.

I really like some of the stuff posted here. I really like John's pic of the rear supports relative to the gearbox mount with the floor removed. I think that's also an excellent choice.

I like the header bar at the front. I did something different however. I stuck it up in a little trough in the roof. It's nicely out of the way and poses no more danger than the roof reinforcements it's hiding behind.

Racerrob

Great ideas guys, keep them coming. JR, interesting door bars, I may look into those. John, thanks for all of your input but especially the header bar. I do want to maximize my headroom as the former cage was a problem for me.

RedlineMan

Hmmm...

VERY interesting door bar structure, Joe. Creative, if nothing else!

Header tubes, eh? Wasn't even going there, but now that you ask... A very overlooked part of a cage. Sad, because it is the most vulnerable part!

Indeed, I usually do put the tube IN FRONT of the exisiting header beam to move it away from the occupants.

The blue car is a current project. It is a street car that will see track duty. I am taking advantage of the owners generous budget to integrate the roll cage into the chassis to give it less of the race car appliance look. Better long term aesthetics than the ugly and fragile SFI 38.1 HD padding. Safer too.



The header tube is placed in front of the exisiting roof beam. The orignal header interior panel is modified with a fabricated aluminum structure that slips over the cage tube. The aluminum panels are covered with SFI 38.1HD padding on the side facing the occupants, then the valley will be filled with expanding foam, smoothed, and then black vinyl will be stretched over it to form a new flush removeable header panel that completely covers the cage. Smooth, safe, and visually pleasing.



My car has a different header than I have seen before. I used two 1.5 tubes instead of the usual single 1.75. More strength with less veritcal space taken. It is also webbed and tied into the existing roof structure at the corners, and also in the center to create a substantial beam structure for more strength in this vulnerable area.

Skip Wolfe

I like the pyramid style X bars as seen on the 997 Cup cars. A guy did some FEA on the different styles a while back on the RL and found those to be the strongest.

APKhaos

Although my cage is very different to John's the main hoop rear stay tubes attach in exactly the same place as his.



I had a very high speed rear-first tire wall impact [Down hill from T10 at VIR for the nosey] which resulted in the car literally sitting up in the tire wall - no wheels on the ground. The tub was marginally repairable, but I've decided to go with a full body transplant.

The deformation stopped about a foot short of the rear tube attach points, but just about everything behind that point was completely collapsed. There was a long debate here when John was building his cage, but I'm here to testify that this main hoop rear support geometry really works.

JR944

Thanks John, coming from Mr. Cage Creativity himself!

I've never seen either of your header designs in a 944 before either. The "integrated" one reminds me of some Ruf's built with integrated cages that at first glance aren't even noticable in a finished car.

I LOVE the door bar design on my car. It's not quite as easy to enter/exit the car as my old car with the single diagonal door bar, but much easier than a standard X design. I'm very comfortable that there's no loss of strength/safety compared to a standard X. The only down side to my design is a bit more weight. ("Nascar" bars protruding into the door cavity would have been safer and heavier yet)

Thankfully, the car just barely makes it down to PCA minimum wt. with me in it. The entire cage is 1.5"x.095 chrome moly which saved about 20% of weight vs. using .120 mild steel.

Joe

Cory M

I didn't like how close the steering was to me in my 944, the Momo adapter and quick release were too long and it wasn't comfortable even with a wheel with a minimal amount of dish. I was able to modify (shorten and tap) the momo adapter, then I bought a spacer and had it turned down to the length I wanted. I also had to buy longer bolts. It was kind of a pain but a hell of a lot easier and cheaper than cutting up your cage, you should see if there are any other options before breaking out the sawzall.

stownsen914

Those are some nice cages in the pictures in this thread.

X braces and pyramid-style braces in the door area are indeed strong, but may not prevent intrusion into the cockpit in the event of a T-bone accident. Nascar-style door bars are a necessary safety feature in any cage, in my opinion. I just saw a video of a hideous racing accident in which a driver was killed when he got T-boned ...

RedlineMan

Oooops;

Sorry to hear that, Tony. Glad you are OK. Great cars, eh? Take it from me, folks. I've been doing collision repair and estimating for over 20 years. The area that Tony mentions did exactly what it is designed to do. Adding tubes to that area is utterly redundant, and may reduce safety. Let it wad like it was designed to!!

Racerrob

In looking at most of these photos, the cars have the roofs off. Obviously that allows better access to work. My roof, however, is welded shut (long story). Do I have a big problem or is my builder just going to shoot me?

RedlineMan

hey;

It can be helpful - depending on design & layout - but it's not absolutely necessary.

s2steve

This thread is perfect timing for me. Last week I cut the rear braces out of my cage because they had bends in them. This was a CDOC cage that claimed to be compliant to most sanctioning bodies. I later learned NASA was not one of them. Not blaming CDOC, I should have done more research. Anyway, the cage also does not have a diagonal brace in the main hoop. The current NASA rules talk about where both ends of the diagonal brace must be located but do not state that it must be one continuous piece of tubing. I would rather leave in the existing horizontal brace in the main hoop (the one on which to mount the belts) and put in two pieces of tubing to make the diagonal brace. Or, if it has to be a continuous piece I will also have to cut out the horizontal piece, install a diagonal then install a new two piece horizontal. Any NASA rule interpretors would be appreciated.

Also have to install a second door bar. Does the second bar have to go from the main hoop to the front hoop or can it attach from the main hoop and intersect the existing door bar, not coming all the way forward. Only want to do this for easier egress.

RedlineMan

Hey Steve;

I thought it stated the diagonal had to be one piece. It probably should be anyway, eh? It says "two door bars." You are pretty much free to do whatever you want, because it does not make any demand beyond that. if there are tow tubes there, you pass. Beyond that, you could actually make the second one effective!

Cris Brady

Hi Steve,


From the NASA 2008 GCR
15.6.7 Diagonal Brace

Hmm, one end to the top of the hoop, and the other end to the bottom plate. Sounds like one piece to me.

Of course, if you want a definitive answer, just like everybody here tells you not to rely on rennlist for PCA CR rules interpretation but ask directly, you could email Bryan Cohn the competion director for nasa competition@drivenasa.com