Exo Car 'Ghettocet' Build Guide: Roll Cage Intermission

Let’s call this intermission on the Ghettocet Miata. A time to get up, stretch our legs, and see how far we have come. Frankly, I let my imagination run wild during the roll cage build, which has taken significantly longer than anticipated.

Intermission

It’s been two weeks since my last post, and I wanted to let you guys know I am still here. There was no failure to launch this time around. In fact, the building of the Miata Exo Car has inspired me to bring projects out that have lived in my head for over 20 years. But first, the update and the current state of the car.

Ghettocet exo car miata with the roll cage roughed in. — Here we are. There is still a lot of welding to finish, but the roll cage is cut, bent, and roughed in.

The Build

During the roll cage build, my design changed a bit. I kept in mind that I wanted the car to accommodate larger drivers and installed a main hoop that is 4 to 5 inches higher than the standard roof line on the Miata. Then, I recessed the harness bar so that the driver’s race seat could have a greater angle of recline to further accommodate the taller drivers.

I must admit that it took me more than one try to get used to the tube bender again. So I bent more than one main hoop out of plain and messed up a few a-pillar bars in the process. As a result, I changed the door bar design to include a single bar parallel to the door frame with two triangulated pieces intersecting the bar. This design should easily pass tech, but there is plenty of room to add an additional NASCAR-style door bar if necessary.

I originally planned on keeping the factory windscreen, but I ran the A-pillar bars on the outside of the windshield frame. This created an ambiguity in the rules that I could not get a straight answer to. Namely, must the forward bars remain in the windshield frame? As a result, I cut the frame out and will run a Lexan piece as the windshield.

Finally, the front and rear strut towers are tied into the cage design. This will yield an extremely rigid chassis that is perfect for track abuse.

The main roll hoop is triangulated to the rear strut tower mounts. — The main roll hoop is tied to the rear strut mounts. These are then triangulated to the door bars.

The door bar of the exo car roll cage. — The door bars triangulate to the main portions of the cage. If necessary, I can easily add a NASCAR-style bar.

There is a lot left, but first, I must finish welding the cage. Many of the joints are tack-welded now. Then, the dash bar needs a steering column mount. I will also use a dimple die to attach the forward body to the roll cage and dash mounting points. So check back, the hard part is almost over and this thing will start coming to gether quickly.