Seven Points are Better than Five

Racing harnesses meld the driver to the machine so the two can become one. The driver can use his or her arms and legs to give precise inputs into the vehicle as opposed to using those arms and legs to stay in the seat. A racing seat also can help with this process. Many NASA drivers in the Time Trial and HPDE ranks may not have racing seats, but would like the additional safety features of a harness system, as well as the melding component of those harnesses to help them drive the car. The problem is stock seats, designed for comfort and a three-point lap and shoulder belt, don’t always allow for the proper placement of a harness system.

Understanding occupant kinematics and collision forces helps you appreciate the importance of a well-designed harness system and how important that system’s installation is. With a racing seat, you have large holes for shoulder belts to pass through without any interference from a headrest. Racing seats have a hole in the proper position of the base of the seat for a submarine belt, so the occupant will not move forward during a frontal collision. Stock seats generally don’t have these holes and so it is difficult to properly install a harness system. I have seen many people install a five-point system — two lap belts, two shoulder belts, one submarine belt — with a stock seat and the submarine belt is routed in front of the seat, far from the crotch of the driver. This placement of the submarine belt is incorrect per the instructions that come with the harnesses. Other drivers have chosen to use a six-point system — two lap belts, two shoulder belts, two submarine belts — which connects the two-point sub belt behind the seat. This type of submarine belt is good for a formula car where the driver is in a laid back position but it doesn’t work well for an upright stock seat. When the shoulder harnesses are tightened, the lap belt moves up to an improper position. With a lap belt too high up, a driver can be injured in a collision if the lap belt is running across the stomach, as opposed to the top of the thighs near the pelvic bone, a strong part of the body.

Using a seven-point harness system allows the single forward belt keep the harness system correctly positioned on the lap while the shoulder harnesses are tightened. The second purpose is that the two rear attachment points of the three-point submarine belt will keep the driver from moving forward in a frontal collision. This is a great system to employ with any seat, racing or stock, but it pays bigger dividends with a stock seat, which doesn’t have holes for the correct positioning of a submarine belt.

A solution for this problem, especially with a stock seat, is a seven-point system — two lap belts, two shoulder belts, three submarine belts. The three-point submarine belt has a single forward connection, like a five-point, and two rear connections, like a six-point, for combination that allows the best of both worlds. The forward belt ensures the lap belt is the correct position when the shoulder harnesses are tightened and the two rear belts keep the driver from moving forward in a frontal collision.

Autopower makes almost unlimited combinations of belt systems, giving racers the choice to pick and choose what sort of harness system they want, HANS shoulders, clip-in or bolt-in lap belts, three-point submarine belts, you name it. Autopower also will custom-build systems for specific applications. All Krider Racing vehicles use the seven-point harness system, even racecars that have full containment seats, based on the advantages of the three-point submarine belt. Most connecting systems are universal and you can upgrade your submarine belt without purchasing a whole new belt system.

If you have a harness system in your vehicle, especially one with a stock seat, take a good look at how your submarine belt connects to your lap belt and be honest with yourself: Is it the proper installation? Will it hold you in place in a crash? If the answer is “I’m not sure” then upgrade to a three-point submarine belt. Call Autopower and tell them you want the Krider Racing Special.

Pro-tip: When you are installing a set of lap belts in a production sedan, before you drill yet another hole through your floor pan, consider mounting the eye-bolt into the O.E.M. stock seatbelt mounting location. The threads on the eye-bolts from Autopower are the same as most seatbelt bolts. Using the O.E.M. bolt hole is a strong and tested location designed for the load.
When installing clip-in seatbelts the first mistake made by racers is the failure to put a cotter pin in the clip-in mount. The cotter pin ensures the clip-in mount cannot fall off of the eye-bolt. NASA tech inspection officials find this oversight all the time while inspecting racecars.
Here you can see we have installed our two rear position eyebolts for the placement of our three-point submarine belt. It is crucial to measure inside the interior and transversely also underneath the car to ensure a good location with room to install the washers and nuts before drilling through the floor pan.
Without a submarine belt, it is easy for the lap belt to move upward when the shoulder harnesses are tightened. This is a big problem because a belt in this position can cause serious injuries to the driver in a frontal collision. Anyone who has installed a harness system without using a submarine belt is at risk for making this mistake.
This photograph is not what you think. We are not measuring the manhood of this driver. What we are showing here is that using a single sub belt with a stock seat means that your body can move 7 inches forward in a frontal impact before the submarine belt will do its job and smack you in the family jewels.
Autopower is known for its massive catalogue of bolt-in and weld-in roll cages, but its safety equipment doesn’t stop there. Autopower offers numerous configurations of harnesses, including a seven-point system with HANS shoulder belts as seen here. Autopower also will do custom orders, like this system, with red flaps to easily loosen belts and a three-point sub belt.
These large washers help spread the load of a bolt through a floor pan. It is crucial that the washer lies flat. When a mounting hole is close to an obstacle you can use a grinder to take off some of the material to shorten the radius of the washer so you get a solid flat fit. Remember to use a lock washer or a Nylock nut to keep it from getting loose. We can cut off the excess thread to save weight.


Image courtesy of Rob Krider


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