Switching from a traditional...
Switching from a traditional five-point belt system to a six-point system with two leg straps does not complicate the buckling system. The leg straps thread onto the shoulder belt buckles before they are locked into position. If a fast exit is necessary, simply releasing the buckle frees all six belts.
VanGilder says the key component of the harness system for protecting the driver-even against head and neck injuries-is the hip (or lap) belt. This is because when you are in a seated position, the pelvis is the center of mass in your body. It is also capable of handling the greatest amount of pressure without injury. VanGilder says that by properly restraining the hips and pelvis, it is much easier to maintain control of the rest of the body in an accident.
"When your pelvis is locked in place, your body produces less momentum and it is easier to control your head," he explains. "Again, the belt should run straight across your hips without any curves or bunching up. Where you've mounted your lap belts to the seat hoop is also important. Once the belts exit the seat, they should come just about straight down. Ideally, you want the lap belts to mount at the same width as your hips. Consider how you would tie down a box in the center of the bed of your pickup truck. If you could, you would anchor the straps as close to the sides of the box as possible because if the straps were anchored way out wide, the box can slide around underneath the strap.
"Also, you want the lap belt anchors behind the tail bone laterally. This helps pull you down into the seat. Combine that with a slight angle to the bottom of the seat, and this really helps lock you in place. Now, in the event of a frontal hit, you would have to rise up before you could come out of your seat."
The crotch strap is also referred to as the antisubmarine belt. Its purpose is to keep you from sliding underneath your lap belt, but it is also useful to help make sure your lap belt stays properly positioned. Often, male drivers are uncomfortable if the crotch strap is too tight, but it must be at the proper length so that the lap belt cannot ride up over the hips and onto the stomach.
"You've got to make sure the lap belt stays on your hips because your hips can take over 4,000 pounds of force without you getting injured," VanGilder explains. "But just at 800 pounds of load across your stomach, you are going to get hurt. That's a big difference in terms of what we can do to protect you on the racetrack. Right now, I have systems that can take a 72g hit and still properly protect the body so that you should be able to walk away from the car. But it's all about seatbelts and angles. If the angles and the position of the belts aren't right, then nothing will protect you."
You may also want to consider switching out the standard five-point harness system with a crotch strap to a six-point system that ditches the single crotch strap in favor of two leg straps. The leg straps wrap across the inside and top of the legs before securing at the buckle. They are an improvement over the crotch-strap system because they assist the lap belt in anchoring the pelvis. Also, male racers are often more comfortable with the two leg straps and are willing to cinch them down tighter. VanGilder says that the six-point belt systems are quickly gaining popularity because they are both safer and more comfortable, and he estimates that 90 percent of the seats he is currently selling are configured for the six-point system. The leg belts (and sometimes the crotch strap) are the only portions of the harness that do not attach directly to the rollcage. Instead, most seat builders mount these belts to a steel plate that is located underneath the aluminum racing seat.