We used a combination ruler/level/angle finder to find and transfer any angles to the tubing before cutting it to size. | 
Since both the NHRA rules and the instructions called for an X-brace from the main rollbar to the rear floor, we decided to install ours to the floor just above the rear shocks. This is another area where the suspension reacts, so supporting the floor here will add to the overall stiffness of our chassis. | 
Since we installed frame connectors in our car, we welded the required additional bar from the main rollbar to the frame connector for additional support. If you don't have frame connectors, this bar is installed to the floor with another metal plate. |
The diagonal side bar, or door bar, is welded from the main rollbar to the forward down bar where it attaches to the metal floor plate. | 
The cage needs to be connected to the car's forward frame, and we've found this to be the easiest way to do it. By passing a bar from the forward down bar, through the firewall, and welding it to the front framerail directly behind the upper control arm, we triangulated the frame in the area where we removed the inner fender for the headers. | 
From the inner fenderwell you can see how we had to cut the firewall to pass the forward bar through. We'll cut a sheetmetal patch to seal the firewall when the cage is finished. This forward bar greatly improves the strength of the forward framerails, and also protects the driver's lower legs in the event of an accident. |
Before welding this in place, the driver should be in driving position to ensure this bar passes midway between the driver's shoulder and elbow. | 
Once all the bars are tack-welded in place, we used our Lincoln Electric mig welder to finish weld all of the joints. We aren't welding experts, but by using the reference guide inside our welder to set amperage and wire feed speeds, we ended up doing a decent job. | 
Remember, pretty welds aren't always good, and good welds aren't always pretty. The key is to get enough heat in the weld to fully penetrate the base metal. Our welds aren't the prettiest, but they have good penetration, which is more important than looking pretty. Weld short beads at intervals, moving around the car, so that you don't heat warp one area. This is similar to stitch welding sheetmetal body panels to avoid heat warpage. |
Even if your welds don't look pretty, don't grind them. The NHRA won't let you through tech if your welds are ground off. If you really screw one up, the correct way to repair it is to completely grind out the weld and weld it again. | 
Since the rollcage is made from untreated, raw, mild steel, it begins rusting very quickly, especially after it's been touched as the oil in human skin accelerates the process. After we had our cage installed and welded, we sanded and treated the cage and floors with rust inhibitor to prep them for paint. | 
Once painted, the cage looks great, way better than the rest of our car at this point. Follow along in future issues as we finish the interior of our project, wire and plumb the car, install a bulletproof drivetrain, replace the glass with polycarbonate windows, and head to the track for some testing. It's a lot of work, but project B3 will be at the track before you know it! |