Or 'vert

Jcc,

Point of the discussion is this. While you are indeed right that there is a lot more computer modeling of vehicles today you cannot say that they model for racing stress on a mass produced car nor is there any serious computer modeling involving racing type stresses on our old stuff. Except maybe the aftermarket company that has the four post setup, I forget who that is off hand.

So you have to try things to see what works and know wy somethings were done and how they worked is about your only realistic option when it comes down to doing things. To me, it sounds like Mr. Bunch did some "computer modeling" with his popsicle stick frame mockup. The sticks being the drawing and his head the computer.

I think many of us agree more then we realize.

Regarding this lower X brace, I will freely admit it almost always has to help. Mr bunch findings trully surprised me. However what often happens with new found info is a solution of the month forms. What I also suspect is that Mr bunch had effectively a "X" on three other planes, and this lower 4th X gave him the remaining positive results. My suspicion here is on a OEM floor panel car, without little other effective "x"'s in the other 3 planes, it will be little served with the lower X regarding torsion. I would also think it is doubtful if Mr Bunch would have tested my hypothesis, because they don't race cars at his level like that, and that info would serve little purpose to him. I also believe and have no data to support that SFC also are not an efficient solution to torsional flex, even I am sure they do add something as many profess. I just don't like to settle for a base hit when some extra thought can get me a home run. And I am too lazy to balsa mock up my theory.

The strength of a triangle has been know for a very, very long time. I wouldn't be afraid of stating it was known long before we ever started applying it to cars. In the early years of auto production, I'd imagine engineers were simply apply general principles to things until cost, weight, etc, became issues and then approaches were evaluated. The application of triangles to race car construction have similarly been around for a very long time.

Since Glenn was designing and building his own car, he may not have been as in tune with the principles as someone who was more dedicated to racer's success on a large scale, like Larry Rathgab. As outlined on Glenn's website, conversations with Larry. and others at very high levels of competition, yielded big increases in performance for Glenn's efforts. FWIW, Chrysler integrated the X braced floor frame wholesale into its kit car program that was developing in the early '70s. Since then, any number of reputable, and not so reputable, chassis builders incorporate X floors into their designs.

The specific reason for it, beings as I'm no engineer, I'll jump on the parallelograming band wagon with this one as suspension loads do tend to transfer diagonally and the X does both resist distortion of the rectangle frame and provide a straighter path for load transference. You have to remember that sub-frame connectors were devised from the drag racing world where beam resistance was more important than diagonal resistance.

Installing an X in a street car is a major pain, but can be done. The X can serve as the lower closure for a driveshaft loop so interference there is not a biggie, but exhaust pipes do compete for the same space. You can build in pass-throughs like some companies do or use oval tubing to avoid some of the clearance loss.

Also, unfortunately, Glenn's website has changed several times over the last decade to omit a considerable amount of building details on this car. If you haven't read through it all, you may not realize that this car is far from a stock bodied race vehicle. It is a purpose built race car with only a few select sheet metal panels to identify it as a Challenger.

I actually like it better back when he called it a '74 and had the matching grill to back up the claim.

Supposedly this Superbird recreation has an X brace for the SFC..... don't see any pics of the X brace on this page so far.......

http://moparblog.com/bill-goldberg-1970-plymouth-superbird-on-ebay/
Edit:

Found build pictures on this link there are shots of the X brace under the car:
http://ghostworks.yearone.com/superbird-build-shots/?show=gallery

So no SFC, because the side intrusion cage bars solve that issue(?), and I like the usability of that design for a street use car, the x looks like 1x2"? material, and whose front end kit is that?
I wonder on cars like that if they just sometime go thru the motions for the look, since its likely never intended to be raced hard.
It does look cool.

When I read that write up where they say something about how heavy duty the X floor brace was I have to admit seeing 1 x 2 square tube didn't fit the visual they painted in the write up.....

On that 2001 T/A the guy that installed the X brace said he had to do some maneuvering with the corners of the car to get it all squared up for the X Brace to go in....

I've watched various U-tube videos of this Challenger... its awesome.. very undertstated... super-awesome on the road courses!

He hasn'tposted anything new in some time, or updated his website. Does he still campaign the car, or did the economy get him too? S/F....Ken M

No idea. He did have it out for the Ultimate Track Car Challenge in 2010.

His website has gone through a number of changes in the ten years I've been following it. It actually has less detail and information on the Challenger now than anytime in the past, but it is also expanding with other cars. I suspect he may be diversifying his interests and the Dodge is semi-retired.