Screaming down a drag strip is one of the most exhilarating rushes you can experience, but to enjoy it properly, having the right safety equipment is a must. At specific e.t.’s, the NHRA requires you to have a roll bar or roll cage, and there are a lot of options out there to add one of these to your vehicle. We sat down with S&W Race Cars, one of drag racing’s most recognized names, to talk about what to look for in a pre-made roll bar or roll cage.
Roll bars and roll cages are available in many different styles and configurations, but they all have to meet the basic requirements set forth by those who create the rules. As a racer, you can have a chassis shop fabricate a custom roll bar or roll cage that will be legal for your desired e.t., but you can also order a pre-made unit for your specific make and model of vehicle that will fit the rules. Racers will go the pre-made route to save money on fabrication, or so they can install the safety gear at their home shop.
The Bar Basics
Most of the requirements for safety gear in drag racing are based on guidance from the SFI Foundation. This organization provides the specifications for how safety gear needs to function. In the case of roll bars and roll cages, they have laid out what size of tubing needs to be used, the wall thickness, how each bar is arranged, and where they’re placed inside the vehicle. This breaks down into how many “points” a roll bar or cage needs to make contact with the vehicle. These points are how you distinguish an 8-point, 10-point, 12-point roll bar or roll cage.
How a roll bar or roll cage is made should be something you look into when purchasing a pre-made product. John Burke is an engineer at S&W Race Cars and he explained what’s important in the production process of these parts.
“The best way to cut the tube is with a plasma cutter — a programmable unit like the one we use is perfect for batch jobs. All of the tubes will be cut exactly the same, and the machine can be programmed to put notches in the tubing. That way it doesn’t require the use of another machine to notch the tube that could vary between pieces of tubing.”
The tubes will also need to be bent; this is another job that’s best handled by a hydraulic bender that can be programmed by an operator. One of these machines has a program uploaded for each part and follows the design instructions for that part to the letter. This means that each roll bar or roll cage created will be the same and won’t have any variation from the design. Having bends this precise will make the installation much smoother, and prevent the person welding the parts from having to make adjustments.
If you’re looking to go faster than 8.50, you need to get a funny car conversion and start looking at the SFI requirements. – John Burke, S&W Race Cars
What if you already have a roll bar or roll cage installed in your racecar, can you upgrade it with a premade kit? Absolutely, but you need to ensure that you know exactly what you’re getting into. Burke recommends these types of roll cage conversions be used if you’re going from a 10.00 e.t. roll bar to an 8.50 e.t. certified roll cage. These kits will include the roof hoop, A-pillar bars, and the dash bar, depending on what your base roll bar is.
“If you’re looking to go faster than 8.50, you need to get a funny car conversion and start looking at the SFI requirements. For that, you need to really consult a professional chassis builder to make sure the conversion will be what you need. It’s really important to look at the rules to be sure you are doing the conversion correctly.”
Burke continues, “All of our conversions are 1-5/8-inch tubing and it will work with the 1-3/4 tubing. We suggest people don’t mix chrome-moly and mild steel when they’re doing an upgrade — the reason is you’re going to have to spec the car based on the weakest material, which is the mild steel. If you’re wanting to build an SFI cage you really don’t want to mix materials.”
Roll Cage Styles And Materials
So you know you need to add some bars to your racecar, you know what to look for, but what style should you get and what does it need to be made of? These are the types of questions you need to have in mind before you start tearing the interior out of your car or drop it off at the chassis shop.
There are three basic styles for roll cages: through the dash, around the dash, and the runner style. Knowing which one to get in a pre-made kit is something you have to do a little bit of research on so you get the right one for your vehicle and application. The easiest one to understand is the through the dash…the name is self-explanatory because the A-pillar bars go through the dash and connect to the dash bar behind the dashboard.
The around the dash is designed so the dash itself doesn’t need to be touched when the A-pillar tube and dash bar are installed. Burke explains what goes into creating one of these roll cages.
“The bar goes down along the A-pillar and bends so it won’t touch the dash, and then bends forward so it will hit the floor panel. The reason we bend the bars forward is because if you just ran them straight down after the dash it would make it really hard to get in and out of that car. With newer cars that have the cab-forward design, it really restricts your ability to get in and out of the car. Racers like to use these because they don’t want to put a hole in the dash that could damage electronics, but that tube could come down in front of a vent or some control instead. It’s a compromise you have to consider if you don’t want to put a hole in your dash,”
A runner-style roll cage is different than the through the dash or around the dash — it uses a bar that goes from the floor up to the A-pillar and runs along the window and connects to the main hoop. The runner-style is used instead of the roof halo hoop for vehicles where the roof halo won’t fit. This style of roll cage can be a challenge to make and install.
“For a DIY person, it’s harder to install a runner-style and it’s harder for us to manufacture, so we tend to stay away from these when possible. The roof tube will have at least two bends in it and there’s a rotation that’s required in that process to make it fit so it will follow the door line. We don’t recommend getting an A-pillar bar that has more than one bend because each one creates another point where there’s no support,” Burke says.
The EWS tube is strong enough and saves our customers some money so it’s a good overall choice. – John Burke, S&W Race Cars
Careful consideration needs to be used when you’re selecting the material of your roll bar or roll cage. S&W offers its products in standard mild steel EWS (electric welded seam), mild steel DOM, and chrome-moly steel. Each of these materials provides advantages and disadvantages,…they also need to be welded into the vehicle differently.
The two most popular materials for a drag racing roll cage are the mild steel EWS and chrome-moly. Which material you use will depend on what certification you’re looking for in your roll cage and how much money you want to spend on materials.
“For someone who’s building a roll bar or roll cage for 8.50 or slower e.t.’s, we go with EWS and use a .134-inch wall tube. This tube is way over the minimum sized required. What we learned is that if the material came out of the mill at the minimum spec and you put it through a bender, that material will get stretched. What that means is you’re going to have material that’s now below the minimum thickness requirement for the rules. By going to .134-inch, we’ve never had that issue,” Burke says.
Now, chrome-moly steel may have the same density as EWS, but it is slightly stronger so that means the wall thickness can be reduced. This is why a chrome-moly roll cage will weigh less than your standard steel roll cage.
“Chrome-moly is the best choice if you’re trying to save weight. We bend our .083-inch chrome-moly with a mandrel tube bender so that helps keep its thickness intact on the tight side and the long side. We’ve never had trouble with that being too thin. That .083 allows us to cut the overall weight of the roll cage by at least 30-percent, Burke explains.
There are numerous factors that go into selecting the proper pre-made roll bar or roll cage. The best course of action as a racer is to really do your research and see which will best work for your application and vehicle. You can reach out to companies like S&W Race Cars to learn exactly what you need to look for before you decide to begin work on your safety upgrades.