Examined, Stickered, And 9-Second Legal

A digital CWG-2 ultrasonic gauge is used to measure the thickness of the rollcage tubing and will instantly determine whether or not you’re legal. The minimum wall thickness allowed for mild-steel (MS) tubing is 0.118 inch, while chrome moly (CM) must meet a 0.083-inch minimum thickness. The main difference between MS and CM is cost and weight. A chrome-moly rollcage can shave off 60 to 80 pounds of weight compared to mild steel, but costs nearly twice as much.

The NHRA’s Division 7 tech guy, who goes only by the name “Kiwi,” made the trek out to Los Angeles County Raceway for a nominal service fee consisting of mileage plus $75 for the serialized certification sticker. We rounded up a couple of other guys who also needed certification to split the cost. Here Kiwi places an ultrasonic probe throughout the entire ’cage to check for proper wall thickness.

Kiwi lifted the carpet to make sure the mounting plates met the required 6x6x0.125-inch dimensions. It’s important to note here that the rollcage must be welded directly onto the frame if one exists. On vehicles with unibody construction such as ours, a plate will suffice so long as it is welded to the floorpan. If you decide to bolt the plate in, you’ll also have to put a duplicate plate on the opposite side of the under carriage to reinforce the floorpan.

Another key visual inspection point is the quality of the welds. They must be free of excessive welding slag (otherwise known as crappy welding) and no portion of the welds may be filed down to smooth out the weld itself.

While the NHRA requires a window net on cars running 9.99 or faster than 135 mph, it’s your local track that will enforce this rule. So if you’re looking to certify your car and don’t have one installed yet, don’t fret about it too much. As long as you have the seat, pedals, and steering wheel in place, you shouldn’t experience any problems. This means you can get the ’cage certified while the car is still under construction.

We passed! All the welds looked great, tubing thickness never went below 0.121 inch, and we had all the required 6x6x0.125-inch plates.

With our serialized NHRA certification sticker in place, we’re good for three years...assuming we don’t crash or go faster than 7.50s. That’s another issue altogether.

The back-pinning, big-time adrenaline-pumping, white-knuckle antics of drag racing are fun, but they can get dangerous, too. Trying to control a car that can go from 0 to 135-plus mph in the quarter-mile in just a hair over 10 seconds is a challenge. At this rate of volatile speed you have to wonder who’s really in control—you, the car, or fate? It’s this kind of performance that has made the National Hot Rod Association (NHRA) mandate strict guidelines about who is and who isn’t allowed to “legally” operate a vehicle at these extreme levels.