roll bar design input needed

I am incorporating dual hoop roll bar mounts into my sub-frame and would appreciate some input on dimensions so that it looks right, in proportion to the stock seats, and clears the soft top.

Input on bar OD, height, bend radius, and width would be appreciated.

I am thinking of welding a flange to the cross brace under the rear seat to pick up the roll bar. I have an additional hoop on the rear sub-frame to address rear end droop, and can mount the rear diagonal to this. Roll bars will be flanged so that the body can be removed.

No roll bar, unless you're planning on wearing a helmet while driving.

I agree with Terry from a safety perspective, but like the looks of the double hoop. Since mine isn't cosmetic, I did a bunch of math before we welded anything.
Inside diameter from one pipe to the other at the base of the curve is 11 inches.
I have inch-and-three-eighths DOM tubing for most of the round pieces of the car's cage, so it's a consistent design element.
That 14.75-ish outside diameter mimics the arches of the front fenders very well and makes the roll bars look like they belong on the car, IMHO.

i bought a porsche boxster roll bar, cut and welded it to fit mr mango. It's sitting on my garage floor right now. it fit the lines of the car, but i never got around to installing it.

http://images.google.ca/images?gbv=2&hl=en&sa=1&q=porsche+boxster&btnG=Search&aq=f&oq=&start=0

In fact I have 30 year old lumps on the back of my head from the roll bar in my Tiger.

This is largely aesthetic and frame stiffening and may just weld in the mounting points and think some more about those lumps.

I got a big 'effin' one...... rollbar that is...

Robert, it's possible to put a rearward incline on the bars and still make them functional without jeapordizing your dome, but you'd have to make the hoops tie in to something structural with a rearward support bar.
Mine are perpendicular to the ground, but yours wouldn't have to be. I read on the 356 Registry about the perils of a roll bar that wasn't tall enough to do it's job without knocking the driver around, and built mine so they're several inches behind and above my grape.
If I'm wearing my five-point seatbelts, my clearance up and back to the bar is about six inches. If I did the math right, I'll bust both of my knees under the dash before my head gets flattened.
By that point, I'm more concerned about a ventilator than the roll bar. Safe is relative, right?
Here's the design again:

These cars are LOWLOWLOW and that worried me enough to mount HiBack seats.
I was in too much of a hurry during my build to install a rollbar but thats the best solution by far.

If you're designing this from scratch , all you need to know is the rearmost position of the seat back. Then put the bar couple inches behind that.


Cut a 6"-8" oval plywood backing , glue some stiff foam and cover with matching upholstery
Mount to the roll bar however you want. Badabing, instant headrest and insurance against whiplash when G-D forbid you get rearended

What the hell are you guys doing that you're always bangin your head on a roll bar all the time? Unless you have no neck muscles, you shift like a mad man or you're constantly getting ass-ended, how do you keep crackin your skull?
As for safety - it's a plastic car. If that roll bar ever has to come into play you've got bigger problems than worrying about that thing.

Robert, I'm sending you an email. Drawing attached.