RedlineMan

Hey All;

I'm the sort that quietly chews, stews, muddles, masticates, and then flies into action at the drop of a hat. I've been pondering my cage for a while. I needed something that better reflected my ever increasing knowledge of safety systems, and something that might be more conducive to possible future endeavors.

The dam broke last Thursday. Out came the Sawzall and half-an-hour later my old cage lay in pieces on the shop floor. Actually, it was only the rear part of a cage, but nonetheless it is now being replaced. The only thing welded in for keeps is the main hoop, which - being characteristically well integrated - is a little hard to see! 1.5 days work have yielded this;





Comment & Discussion Welcomed!

Al P.

why did you tie the horizontal to the rear support legs?

M758

All I can say is DAMN... It must be cold up there and you must be bored as hell.


It is racing season here in Arizona!

RedlineMan

Hey Al;

The last pic should tell you. Look at the seat position relative to the main hoop. That is where I sit, by the way!

Actually Joe, today was a beautiful, bright, and sunny in the low 50s! Yeh... I'm bored. In between customer jobs. When a window presents itself...

M758

50's and sunny... Wow.. Time for dip in the pool! I think it was like 75 and sunny here. Typical January day really.

Still the loads from the belt bar in a crash would be trying to bend those rear bars from their weakest points.

Seems to me the best idea is to try to tie those in some how. I can see how far back you sit so that pushes the harness bar back. One idea is to tie the bar forward to the main hoop then tie that point into the door bar system then tie it into the foot bar plate.

RedlineMan

This being different that a "normal" setup? I don't think so.

For the sake of simplicity, let's set up a very generic rear cage section. Simple main hoop, 90 degree corners, vertical legs. Rear braces running back to the rear frame sills at the requisite <30 degree angle. Belt bar at the given height running between the main hoop legs. How are they more supported than what I've got mocked up?

Answer; they are not. Not unless there is a door bar structure, or they are somehow attached to the b-pillar. My analysis is that first, my belt bar is shorter by about a foot, which automatically makes it stronger. Second, those rear braces at that angle are loaded in tension more than an upright hoop leg. A large part of the forward force will be transmitted through the length of the brace, pulling up on the base, and pushing into the main hoop junction.

Not to disagree with your thought to question it. Thought the same thing. Just that there is method to my madness. It might even be correct! Touche, mon ami?

SeaCay

Curious as to what tubing sizes you are using, what type and where you're buying it? What do you run as a cover for the open floor sections?

All interesting stuff. I'll be following in your footsteps pretty soon when I get back from Iraq. With all my downtime here I've been toying over all the possible cage designs in my mind. More pics of your project as it progresses would be nice. I have a desktop folder of strictly 944/951 cage design photos that I have downloaded from the net. Gives me a lot of good ideas. Also shows me a lot of what I would call mistakes, all good learning points.

At any rate, I bet you're having fun. Continue to tinker and enjoy!

RedlineMan

Hey;

Haven't seen that screen name in a while. Now I know why! I'm one that supports you guys to the max. Thank you, and best of luck!

1.75x0.95 DOM. I buy it from a local supplier. The rear area is sheeted in aluminum.



I'm not sure I will have time to do the front section (which I have never had in this car). Only so much time in between customer work, ya know. More pics to come!

Mike S.

John...love that tight main hoop...took me a couple looks to find it. I think I see a couple of weld tie in points to the body. If easy to describe, where are all of them?

What are your plans for diagonal members?

For somebody on the other end of the height spectrum, sitting much further forward, and having the harness bar on the main hoop, would you be inclined to move the rear brace tie attachment point further to the rear of the car? Or do you think your new position/rear brace angle and tie in location is universally optimal?

Thanks,

Mike

P.S. 58 deg F right now, no snow to be found here in Buffalo.

gt3cup

John,
This is a bit off topic, but are you an artist as well?
Mark

Mike K.

Easy with the sawzall talk there Big Guy. You don't want it ending up looking like this!

RedlineMan

Hey All;

I'd like to thank Joe for his nitpicking! The truth is that I was ambivalent about that belt bar myself. My practical side said it would never fail, but my Devil's Advocate Design Engineer side said it was not a fool-proof layout. In theory, he was correct, and the same thing had been nagging at me right from the start.

Joe, you pushed me over the edge and so I redid it. I'm really glad I did. I think this is the most original belt bar in existance! Creative, artisitic, unique... and it will probably work great too! And so, I give you, the Joe Bar!



And now the piece de resistance. The belt mounting. Nuts welded into the belt bar to receive the eye bolts. The eye bolts have a jamb nut on them to fix their position perfectly vertical. I set these so that the belts are positioned narrower than the belt opennings in the seat. This creates an inward pull on the straps when they are loaded, which is very good for general belt retention, and specifically created for optimizing a HANS device. The free movement of the spring clip mounting allows them to automatically seek a straight load path.



I've never seen it done this way before. I'm not sure why I never thought of it till now? Just too cool!
Stay tuned. More tubes coming!

RedlineMan

Of sorts. Hopefully, a little bit in everything I do.

RedlineMan

Obviously, it is welded at the base. It is also attached at the beltline (base of the window openning). I'd like to tie in at the roof line too, but reading the NASA rules () suggests they are a bit **** about too many tie in points.

Never you fear, Gargoyle. We have plans. Bwahahahaha. That is the next tube on the agenda. It will be suitably rendered in the style of my new belt...er... Joe Bar.

No. Those were positioned for structural reasons, not with any thought to the harness system. Usually, one places them at the shock mount to counter suspension forces seen by the chassis. Anything behind that sees no dynamic load... unless you biff, and then you'd like the crush zone. I felt the angle was a bit too steep, so I split the difference between the shock mount and the factory x-member.

Unfortunately, the fuel filler is smack dab in the middle of this decision with a stock fuel system. If you look closely at the second picture I just posted, to the extreme left you can see a little half round thing protruding from the sill tube (top of the frame) surface. That is where the original rear braces were located, and this position gave me JUST enough room to squeeze the stock fuel filler neck cover off.

RedlineMan

Never fear, Mike. If I feel the need for vulnerability, I'll ride my motorcycle!