We didn't install a rollbar...
We didn't install a rollbar in our Diplomat to conform to the rules of our class in the Nevada Open Road Challenge, since we didn't need one to comply. Instead, we installed a rollbar to protect the safety of the two yahoos traveling at triple-digit speeds. In order to make our bar compliant, a couple of items would need to be addressed (the diagonal brace would have to be added, as well as an inspection hole). If we run the car in the future in a faster class, we will have to make the changes required in the SSCC rules for conformity.
Finishing any racing event shiny side up should always be the main goal. On rare occasions, things can get dicey and next thing you know, you're upside down. When we entered into this project, we decided no matter what speed class we would participate in during the Nevada Open Road Challenge, we would outfit the Stealth Bomber with a rollbar. It just made good sense, added negligible weight, and provided us with a modicum of security should things go bad at triple-digit speeds.
Since an M-body can safely be referred to as a less-than-mainstream project vehicle, we had to do some measuring to see what application's rollbar would best fit this body style. We decided that we would source Competition Engineering (C.E.) for one of their rollbar kits. Because our project '68 Barracuda is sporting a C.E. rollcage, a quick measuring indicated the width would be perfect for our Diplomat. So we contacted Competition Engineering and carted our rollbar kit over to Sleeper Suspension Development for a custom installation.
Rollbar Rules
The rollbar rules differ slightly between NHRA (National Hot Rod Association) and SSCC (Silver State Classic Challenge) sanctioning bodies, but with the same objective-to keep occupants alive in the unfortunate event of a rollover. The NHRA requires a rollbar in any vehicle running 11.99 or better (13.99 in the case of a convertible), while the SSCC mandates a bar in the Grand Sport division (130- to 150-mph classes with a maximum "tech speed" of 165 mph), and recommends a rollbar in the Grand Touring (115- to 125-mph classes with a maximum "tech speed" of 140 mph) and Touring (95- to 110-mph classes with a maximum "tech speed" of 124 mph) divisions. But the rules differ basically on a couple of fronts. According to the SSCC's rules, a diagonal brace must be added to triangulate the main hoop. The SSCC also recommends that the brace be attached at the top of the driver side of the hoop and to the bottom of the passenger side. Also, the NHRA requires a sidebar on the driver side of the vehicle that must pass the driver at a point between the shoulder and the elbow, whereas the SSCC does not require such a door bar for a rollbar. The SSCC requires an inspection "window" (a hole at least 3/16-inch diameter) be drilled in an area that will not compromise strength (at least 3 inches from any weld or bend) to allow for verification of wall thickness. Rollbar tubing thickness is also regulated by the SSCC based on the weight of the car (any vehicle over 2,700 pounds has to have an 1 3/4-inch bar), whereas the NHRA mandates 1 3/4-inch tubing (mild steel or chromoly) at .118-inch thick (chromoly can be .083-inch thick). There are some other minor differences, but we feel they are negligible. To acquire an NHRA rule book online, log onto www.nhra.com or call (626) 914-4761. The SSCC rules are posted on their web site at www.sscc.us.
Layers of padding/insulation/sound...
Layers of padding/insulation/sound deadener, as well as the heavy rubber floor mats had to be removed in order to weld the rollbar in. This was a chance to remove a fairly significant amount of weight. We even removed the headliner as Sleeper likes to butt the bar's hoop right up against the roof. Yes, the interior is a louder place now that the excess has been removed, but in the end we jettisoned roughly 60-pounds worth of useless weight.
We measured the floor of the...
We measured the floor of the Diplomat in order to center the main hoop, and once the location of the main bar 6-inch plates had been determined, a thorough cleaning of the area to be welded was completed. Wire brushes and sanding wheels aided us in expediting this process. We cannot stress enough the importance of getting the welding area down to bare metal prior to actually welding. Make sure the plate conforms to the contours of the floor. Conformity leads to strength and a solid weld.
Use a level to make sure the...
Use a level to make sure the upright bars of the hoop are straight up and down. Once you tack weld the one side, you can move on to the other side.
We measured the back of the...
We measured the back of the seat to determine where the crossbar needed to be located on the hoop to mount the shoulder harnesses and to brace the seatback properly.
We then took a measurement...
We then took a measurement on the hoop to locate the crossbar, tack welded it in place, remeasured it, and finish welded the bar in place.
The rear down bars had to...
The rear down bars had to be run through the package tray in order to keep the back seat functional. Many times racers eliminate the rear seat entirely to lose the weight and to make room for the rear bars, but since the Stealth Bomber serves double duty as an open-road racer and daily driver, this was not an option. Once we marked the location, we cut it out with a small reciprocating saw.
A sanding disk was used to...
A sanding disk was used to clean the trunk area to prepare the surface for welding where the rear down bars will go.
A chop saw was the weapon...
A chop saw was the weapon of choice to cut the bars to length. Make sure you measure more than once and are accurate with your measurements. You can always cut it again, but you can't put the material back on.
Mocking everything up is important....
Mocking everything up is important. We made absolutely sure that we cut everything to the correct length. From here out it's easy.
When all was said and done,...
When all was said and done, the unenviable task of putting the interior back together ensued. We ditched all of the padding that was underneath and decided to reuse the carpeting. It only required a little bit of cutting to fit around the bars of the main hoop.