Building an entire frame has it's benefits and drawbacks. If for some reason, the owner of this rig ever wants to register it through DMV, having a custom frame makes it a lot more difficult.
As compared to the Savvy/Currie Jeep, this body and roll cage are going to be removable from the chassis, which presents it's own set of problems. One problem is since the rear shocks are to be cage mounted, the triangulation at the rear of the cage and where it meets the frame has to be very rigid, both for performance and durability reasons. The second hurdle was to make it easy to remove the body from the frame. I had Jim Christiansen, formerly of Inchworm gear, machine up some tube inserted bungs that will make bolting the cage to the frame a piece of cake (pics below).
One feature of this FJ that was very important to the owner was that it be a 4 seater and that getting in and out of the rig be easy for the rear passengers so cage triangulation is now important not only for the suspension, but for the safety of the passengers. That means I can't have a bunch of roll cage tubes in the rear where I need them the most. We will be building the cage here shortly so expect an update on that front soon.
Here are some pics.
Bungs for the cage mounts welded into the very rigid slider assembly.
Reinforcing the body tub where the cage tubing will pass through. The tubes will be fully welded through these areas.
Additional plating in the center to support the seat belt bars and seat mounts.