Here is a video of us fitting the front cockpit tube to the body. Most people don't realize how extremely difficult it is to mount an aluminum body. I try to explain it to people that mounting the body is actually much harder than taking a flat sheet of aluminum and turning it into the body in the first place.
Here I will go through the steps of fitting a body to a chassis for the first time. After the first time, it is a lot easier (but still extremely difficult) to mount the body. The first time you have to pay very close attention to the 3D nature of the body and make sure you mount it on correctly AND STRAIGHT! I have seen a LOT of exceptionally poor aluminum body mounting jobs. I have seen exquisite workmanship literally destroyed by people who thought they knew what they were doing.
Here we are actually mounting the body onto the chassis. It is not permanent, but we are getting there. We rivet (or cleco) the body on once we get the measurements correct because clamps can slip...
Here is our CNC tube bender with the simulation page opened up. We simulate the bends before we bend them. That helps to keep the scrap pile to a minimum. The simulation is not perfect, but it sure helps.
We started by welding in the tube here right above the radiator. The first tube is critical to the overall orientation of the body. Mounting a body is an extremely difficult proposition. Many, many people have ruined otherwise wonderful bodies by not knowing how to mount them. Mounting a body is a 3D problem. Most people don't think in 3 dimensions and so the body ends up off in one of the dimensions. It takes a long time and a lot of measuring to get everything lined up correctly.
We had a tremendous advantage in the fact our chassis was already perfectly symmetrical from the wonderful CAD data we had. When you weld an original chassis together, it moves all over the place and it drives you crazy. So, the sub structure is no longer straight--even if you were careful and measured everything CORRECTLY. Welding warps things. Like I say, we were very lucky to have a symmetrical and orthogonal chassis to start with. It made mounting the body much, much easier.
The first thing we did was take the CAD data and measure the leading edge tube for the hood and position it exactly in all 3 dimensions to make sure it was in the right place. Then, we tacked the tube in place.