BUILD-OFF CHALLENGE: Tygaboy's '75 LS3, It seemed a good idea at the time... Options

[tygaboy]

Hi World!
Let the games begin! (IMG:style_emoticons/default/piratenanner.gif)
As the title says, it's a '75 that's getting an LS3 (Cracker's "old" motor - thanks Tony!) and Boxster 6 speed.
Also planned is zippidy doo-dah 911 front suspension with Boxster calipers all around. The rear suspension is getting 911 ebrakes, Tangerine Racing raised pickups and shock towers.
I have plans to stiffen the chassis with a partial cage.

Doesn't that sound like a great plan? I think so, too!

BACKGROUND:
I got this as a roller that was purported to be "dry and accident free". And it was!
Except for all the rust and the place where it was hit. Yeah, yeah... But it's all good. The seller and I worked everything out. (IMG:style_emoticons/default/beerchug.gif)

But our little 914s are full of surprises and isn't that half the fun? So, first up is rust repair time! (IMG:style_emoticons/default/sawzall-smiley.gif) (IMG:style_emoticons/default/sawzall-smiley.gif) (IMG:style_emoticons/default/welder.gif) (IMG:style_emoticons/default/welder.gif)

Let's begin with some pics of what I started with. Wish me luck! Wait, forget the luck, wish me SKILL!!!

[tygaboy]

CHASSIS STIFFENING: Version II - Change of Plan

As I've been thinking about the bolt in design, I spoke with a number of experienced folks (Chris Foley, Tony/Cracker) and some race car fab buddies and decided I didn't want to go bolt in. But I also didn't want a race car cage with full front hoop, etc.

What to do....

I understand the targa structure of our cars are pretty strong and since this is a street car that will see the occasional track day, I decided to build what I'll call a "roadster cage".

The main hoop will come up to just below the rear window, it'll have legs back to the top of the long near the suspension consoles. In the cabin, there will be a hoop under the dash and door bars with drops that tie into the tops of the longs. This will all be installed over the inner long stiffener kit.

That said, I also wanted to hide as much of this "cage" as I could. So I'm trying something a bit different. A "through the firewall" design!

Here's the initial rough-in of the rear hoop. It's roll bent to match the curve of the window opening.

The final fit will have the top of the bar just under the window and able to serve as the shoulder harness mount. The window and all stock interior trim can go in/out. I planned to eliminate the back pad so no worries there.

[worn]

That said, I also wanted to hide as much of this "cage" as I could. So I'm trying something a bit different. A "through the firewall" design!

I like it a lot, but with my flexible car I get noise as the targa top wiggles against the bar. The main flexure I should think would be a bending of the longs open and shut. Sorta like when they fail and the door gap changes. The more you make the bar fore and aft strong and tied in the better. Also you would want to fight twisting motions between front and rear. Instead of a single bar you might try smaller tubing but more truss work. But maybe not since you want to have it bolt in.

I very much like the ideas you have and also your shop!!!! I like my bead roller too.