BMW E46 Racecar
A couple months ago we introduced you to professional skateboarder Rune Glifberg and his 2003 BMW M3, which he wanted to turn into a competition-ready club racer. We left off with Glifberg ripping out the interior-headliner, seats, carpet, door panels-and turning the car over to Evosport in Huntington Beach, Calif., for chassis prep in the form of a six-point chromoly rollcage.
Every bit of fabric, trim, and most other interior amenities were removed, laying bare the underlying metal surfaces, mechanical assemblies, and lengths of wiring strung along the floorpan like so much multicolored spaghetti. About the only bits to remain were the steering wheel-necessary to be able to still move the car-and a Sparco bucket seat bolted into the pan to give anyone driving it a comfortable place to sit while doing so. The sunroof-endowed roof section was also removed to make way for a carbon-fiber panel which will be installed later on.
Smooth, pretty weld seams are not only indicative of an experienced welder; they more often than not also indicate the basic quality of cage fabrication. Evosport fabricators put a lot of effort into making the cage structure both effective and aesthetically pleasing.
Smooth, pretty weld seams are not only indicative of an experienced welder; they more ofte
The factory sound deadening material was also left in place. According to Evosport's Brad Otoupalik, unless a customer is absolutely set on shaving every last ounce of unnecessary weight, most of the cars they prep retain sound deadening. In the case of the E46 M3, it represents only about 40 pounds and it's all applied to the floor sections, the most beneficial place to retain weight. Taking it all out would constitute a minimum two-day job, and depending on the complexity, it'd cost around $1,500 to $2,500-not worth the money in most cases.
With the inside stripped, it was on to cage fabrication. A rollcage is one of the most important safety components in any racecar and Evosport is adamant that this be the first upgrade in any sort of racing build. There are a couple ways you can go about it, depending on the type of track time you and your car will be seeing. Glifberg's is at the more serious end of the spectrum. "We consult with customers and see what they want to use the car for," Otoupalik says. "Rune is a professional athlete, a competitor-we knew he wanted to really go racing."
Mocking up the rear portion of the cage structure prior to welding.
Your basic four-point rollbar is really nothing more than a place to hang racing harnesses from. It doesn't do a whole lot to stiffen the chassis and offers no great degree of rollover protection since there's no reinforcement at the front of the cabin. And it doesn't offer any sort of shielding for your legs or from a side impact, which both become pretty important considerations if you're planning to go on-track with other like-minded competitors. For anyone truly serious about racing, Evosport recommends a six-point cage at the minimum, one that ties into all four suspension points and that includes lateral structures across the door thresholds to prevent cockpit intrusion. A basic six-point, TIG-welded race series-legal chromoly cage will run you $3,900.
Different viewing angles of the rear X structure.
Glifberg's has been taken a couple steps further to increase both chassis rigidity and overall safety. His cage is a six-point assembly, incorporating a second diagonal cross member at the rear that forms an X-shaped brace between the two shock towers. Glifberg's cage also incorporates a more robust structure across the driver-side door. Basic door bars would consist of two tubes that cross in the middle, forming another X and preventing outside objects-other cars, say-from entering the cockpit in case of a smash-up. Evosport offers an upgrade that does you one better, what they call a "pyramid bar." This incorporates both an X-shaped cross structure as well as what's known as NASCAR bars, essentially a setup that angles the bars outward, toward the door and away from the cockpit. This creates a larger cushion of dead space between the potential point of impact and the car's inhabitants. In this case, the NASCAR bars and the X-brace form a rigid pyramid structure, hence the name.