My Kat shock simply fall apart, the shock rod got loose from the top so the spring makes the rear end bounce like crazy if I speed up or brake too fast or at stoplights jump a little bit over the seat, then it bounces; don't know why the shock self-disassembled, gotta take off the shock.

Is it normal for a Kat shock to tear like that? I mean, can I fix it or do I need a new one???

sound bad.....they don't come apart normally....not serviceable

what happens if you retighten the shock rod?

I already reinstalled the stock shock. the Kat shock rod broke a thread of the upper aluminum cap, where the shock is bolted to the frame and the rebound is set. I can't simply screw the rod in back to  the cap because need to compress the spring, and it's quite strong, may need some special tool. If I found the way to do so, the cap thread may be too much damaged to pull the shock rod once reinstalled on the bike and eventally fail again. I'll try to make some pics.

Chuck it and get a new one dude. That sucks, sorry to hear it.