I did a half roll in my Hammerhead Twister 200 and one of the rear post (not much more than a short stub) to which one of the overhead roll cage bars bolts, tore loose. That is, just below the weld (or possibly brazing), a one inch strip of the metal tubing of the main frame ripped out providing an unwanted view inside of the metal tubing that is part or the main frame and allowing the "roll bars" to assume a new posture .

Can some one tell me what kind of metal tubing these cart frames are made of (4130?).

What is the recommended repair? Cut out the bad section and replace with something like the original (but this time properly heated treated or strengthened with a ...gusset plate?).

Any help or directions to find help is greatly appreciated.

Post me a pic of the break and I will help you out.

Yes... please send a picture of the damage. I haven't checked but I heard that some of these are made with an odd ball Chinese sized tubing. Shouldn't matter for a good repair, depending on the damage.