Re: Roll Cage
Quite true - a subframe. Trouble is most folks just punch the downbars through the floor to the frame. They seal the hole with carpet, duct tape or whatever.
Then they tie their shoulder harness to the cage behind them, and the lap belt to the floor.
In a rollover, even if the body mounts hold, the entire thing flexes - the shoulder harness pulls down an inch or so - or more.
Guess what happens to their spine when it's compressed an inch?
If the downbars are tied together with straps or rails between them right along the floor, at least in the front, the body stays with the frame.
Closed body/solid body cars, like NASCAR you'll find the cage is entirely inside the body - and they often tie into the frame - the cage cannot get away from the body since it's trapped inside the body.
But on open topped, or glass topped vehicles it presents a different problem - the body can get away from the frame.
Another safety issue - belts -- 4 point shoulder belts are dangerous - they need the 5th belt, the submarine belt to be safe. What happens with a 4 point in a rollover or crash the shoulder belts restrain your body, but pull up on the lap belt as you go into them. The lap belt gets pulled up above your hips into your soft belly. Your soft belly will sustain all kinds of internal injuries - often fatal.
The single cross strap in stock vehicles doesn't attach to the lap belt in the middle, so it doesn't pull up.
Yes, hooking the sub belt on a 5 point is a pain, but lying in the hospital is worse.
Safety equipment can certainly kill you - like getting hit in the head with your fire extinguisher.