Originally posted by Boccoli1
Also what would be your "times" for connecting and not connecting. Information is always good.
1) When your seats and seat belts are still attached to the floor pan. Reason? If the body comes loose, you go with the body. If the cage is attached to the frame, it will crush you between the body and the cage. You should really attach the seats and seat belts to the roll cage. Some states won't let you move the seat belts - that's when you leave the factory stock belts AS-IS, and add an aftermarket belt that attaches to the cage.
2) When your frame is way to flexy. The cage will stiffen the frame way up - and can cause the frame to crack. (note - explorers don't suffer from this problem, rangers do a little) see 1970's ford/chevy trucks with the twisted bed to cab pics for a reference.
3) Your vehicle of choice doesn't have a frame (ie, Jeep Cherokee, Unibody construction vehicles)
4) your concerned about vibration in the body. When connect the roll cage to the frame, you can stiffen the body up to the point where the rubber body mounts no longer kill vibrations. Normally not a problem, but it does happen.
If you attach to the body, the plates need to be rounded - no sharp pointy corners!
Your best bet - attach to both. It's a royal pain, but in a high speed rollover, you won't lose anything that way.
You also need to gusset, and triangulate the cage.
My zuk has the cage attached to the frame and the body, and the seats are attached to the cage along with the new seat belts. The body pan is now for looks, and to catch the trail snacks.