The first question a tall Miata driver gets is, “How do you fit in it?”
Well, a carefully constructed cage and a well-chosen seat and mounting system are paramount. If you’re just tossing in a seat without a full-containment halo, it’s not difficult to get a tall driver into a caged Miata. However, for racing, a containment seat is a must, and that’s where things can get a little tricky.
For fabrication and expertise, I turned to Tony Colicchio, co-owner of TC Design, a leading racecar fabrication shop in Campbell, Calif. Colicchio estimates that he has fabricated more than 400 cages for Miata racecars, and nearly a thousand roll cages in all. Colicchio first learned about proper cage construction back in the 1990s by reading about the factory-built racecars in trade publications like Racecar Engineering and Autosport.
To give the driver the most room in a Miata racecar, Colicchio lands the main hoop on a plate on the package shelf just forward of the seat belt towers, one of the stiffest areas on the car. It works on other two-seater convertibles such as the Honda S2000. Air-cooled 911s also had a similar pad up and away from the floor, which allows more freedom in mounting the driver’s seat.
“That’s a huge box section in those cars,” Colicchio said. “And the other thing, too, is, especially in a Spec Miata car with the seatbelt tower still in there, that seatbelt tower, each of those weighs about 10 pounds. There is a significant amount of metal in that structure, and that is all contributing to stiffness in that area.”
The landing plate extends down the front of the rear bulkhead and serves as the mounting point for the door bars. Because the Spec Miata rules prohibit notching or cutting the production sheet metal, the door bars take an S bend to land on the plate. That’s not as strong as a single-bend bar that fastens to a main hoop, but with as many Miata cages as Colicchio has built, he hasn’t seen any failures using this design.
“We just need to properly attach them to a good structure. We had a lot of feedback as far as how they were holding up to crashes in Spec Miata,” Colicchio said. “Again, it’s making sure that you’ve got a good mounting plate, you’ve got good support for it. But for the most part, we literally have seen zero issues with it.”
For larger cars, coupes and sedans with greater interior dimensions, a pyramid X bar tied to the main hoops is stronger, and has less of an effect on how much room the driver has. To add strength to the Miata’s cage structure, Colicchio builds the main hoop, windshield bars, down bars and door bars from .120” thick tubing, .030” thicker than the .095” thick tubing required in the CCR for cars under 2,500 pounds.
A rule change in Spec Miata that took effect a few years ago was allowing a dropped floor, which creates more headroom for taller drivers and lowers the center of gravity, although the second benefit is difficult to quantify. Companies such as East Street Racing and Advanced Autosports offer prefabricated drop floors, which weld in place. For the utmost safety, it’s a job best left to professionals.
“With a lowered seat pan, I can get a taller driver to fit better in the car and provide more space. Often that space equals more safety,” Colicchio said. “Unfortunately we have also seen a large number of poorly installed and/or fabricated lower seat pans. This is an item that should be installed with a high level of skill. All of the safety items in the car need to work together as a system.”
With the cage constructed in this way, it’s possible to get a number of different kinds of full-containment seats into a Miata. I used a 15-inch-wide Kirkey Series 71, but Colicchio also has fitted large composite seats.
Another part of creating more room for the driver is where Colicchio locates the bar for the forward hoop, which follows the contours of the A pillar. It welds to a plinth box at the rocker panel a bit farther aft and outboard of the usual locations. That allows the two foot-protection bars that tie the forward hoop to the firewall to be tucked farther outward.
“So not only are we picking up some more strength, but we’re also getting that bar system away from the driver’s feet more,” Colicchio said. “Everything is moved toward the outside of the car, about 2 inches, so that just really helps get everyone some more room and some more safety because of the room. And those foot-protection bars have definitely been tested over the years in Miatas quite a bit.”
Once the cage is installed, there are a couple of other tricks, which have nothing to do with how the cage is built, that make things better for the driver.
One is the use of a mesh-style window net. The 1-inch-wide ribbon nets are plenty strong, but they can block a lot of the driver’s visibility to the outside rearview mirror. To comply with the CCR, you must have an SFI-tested net, and there are a number of good ones on the market. The SFI test procedure is shown here.
The other trick lies in how the cage is painted. Vibrant colors are dramatic and cool, but I’ve always preferred a matte black finish on the cage, the A and B pillars, and the rear package tray. By using black, the cage essentially “disappears” when you install the factory hardtop. By using a matte finish paint, you remove the chance of creating a glare that can create a distraction.
Social science research has taught us that distraction disrupts the dominant cognitive response. There is great deal of research on distracted driving, so suffice it to say that minimizing distraction while behind the wheel of a racecar is essential.
“That’s something I picked up reading Racecar Engineering,” Colicchio said. “You see these rally cars, and it’s like, well, why is the why is the front cage bar all black down to the dash line? That’s why.
“We had a customer in one of our ST4/ST3 E46 M3’s that we build — we do custom dashes in those — and we use a matte black paint,” Colicchio said. “Then over the winter, the customer decided it would be cool to powder coat it gloss black, and first session out, he’s trying to figure out how he’s going to race the rest of the weekend, because it’s right in his eyes. So we ended up using gaffer’s tape for the weekend.”