True SStreet with a totally new front suspension courtesy of TRZ Motorsports and Chris Alston's Chassisworks, along with a beautiful set of front wheels from Billet Specialties wrapped in Mickey Thompson rubber. With our G-body getting close to what resembles a complete roller, it was time to install the 10-point roll cage and finish the required steps out back to install our Chris Alston's Chassisworks anti-roll bar and coil-over conversion kit.
According to the 2008 NHRA Rulebook, a roll cage is mandatory in any vehicle running 9.99-seconds or quicker in the quarter-mile. Cars requiring a roll cage must be inspected every three years by NHRA and have a serialized sticker affixed to the cage before participation. Most sanctioning bodies generally follow NHRA rules, however it is always good to check out your local track or sanctioning body's rule requirements first.
The NHRA also specifies that all cage structures must be designed in an attempt to protect the driver from any angle-360 degrees. All chromoly tube welding must be done by approved TIG heliarc process; mild steel tube may be done by either the TIG or MIG wire feed process. Taking it a step further, a ribbon-type or SFI Spec 27.1 mesh-type window net is also mandatory on any full-bodied car requiring a roll cage.
Building a car that will break the 10-second barrier in the quarter-mile brings on an entire new set of rules and regulations when it comes to safety. Besides the aforementioned roll cage and window net, a quick-release, 3-inch driver restraint system with a 2-inch crotch strap is also mandatory, and must meet SFI Spec 16.1. Additionally, restraints are required to be recertified in two-year intervals. When breaking into the 9s, the driver must also obtain a special NHRA competition license, as well as additional driver safety equipment including a fire jacket, fire pants, fire shoes, neck collar, gloves and an approved helmet. Licensing and driver apparel will be covered in a future issue.
While many chassis shops can bend a custom cage from raw material, we chose to call the professionals at S&W Race Cars in Spring City, Pennsylvania, for a little direction in the matter. S&W suggested that we utilize its 10-point roll cage (PN 11-1516CM), which comes pre-bent per application and shipped to your door. Despite some minor trimming and notching, the cage is pretty much hold and weld. We opted for the chromoly unit, as it is lighter and stronger than mild steel. The reason for the weight savings utilizing chromoly in a roll cage application is attributed its strength. A 1 5/8-inch chromoly tube with a .083-inch wall thickness is mandatory for use, while a 1 5/8-inch mild steel tube with a .134-inch wall is mandatory causing excess weight. S&W also provided us with a window net mounting kit.
Here, all-purpose man Donald Singer sets in our aluminum Kirkey Race seat for measurements. The main hoop of the cage needs to be within 6-inches of the driver/seat. Once the proper locations are marked Donald begins to open up the floor via a hole-saw. Any vehicle with a full frame must have the cage welded to it and not the floor, as per NHRA rules. All metals to be welded to must be cleaned thoroughly via a grinding disc of some sort.