Impact Racing Turns To Science In Shift To 2-Inch Driver Harnesses

Racers across all sectors of motorsport have for decades relied on driver harnesses measuring roughly 3-inches, operating on the belief that a wider strap over the shoulders and waist provide more comfort, durability, and security. And void of science to suggest otherwise, that belief was never really disputed. But modern times call for modern approaches, and as safety equipment manufacturers have poured their efforts into scientifically reimagining helmets and head-and-neck restraint systems in a way they never had previously, the age-old driver harnesses have also been looked at with a fresh perspective.

Impact Racing has played a key role in enhancing driver safety through research and development, and when it turned to driver harnesses, it posed the question, “just because we’ve always done it this way, does that mean it’s truly the best way?”

The answer, according to Impact, is an emphatic ‘no.’

NHRA Top Fuel racer Antron Brown was an early adopter and remains an advocate of the 2-inch Impact belts.

“What we’ve learned about bio-mechanics has changed things a little bit; it’s a progression,” explains Ben O’Connor, VP of Sales at Impact. “We’re really understanding now how the human body works in relationship to the restraints. There is an actual science to it.”

O’Connor goes on to state that “we can definitively say there is no trade-off between 2- and 3-inch belts. There is no reason today to run a 3-inch restraint. The origin of the 3-inch restraint we use today was that someone, at some point, had taken a set of restraints out of a fighter jet and put them in a racecar. They worked great for what they were doing, and the textile industry being what it was back then, the belts weren’t as strong as they are today. So the 3-inch width was really considered a necessity to gain the strength they needed.” 

Advances in the design and manufacture of the webbings in harnesses, however, have led to considerable change.

“In early forms of motorsports, the 3-inch width, the webbing, was definitely required to get the strength that they needed to meet the requirements of foundations like the SFI and FIA. So it’s really strength issue,” O’Connor says. “But as early as the 1990s, the textile industry advanced and the webbings got considerably stronger; the amount of stretch, the overall strength of the webbing increased, and there was no longer an issue. From that standpoint, there was no need to continue with 3-inch belts. There are arguments to be made that wider belts spread out the load, but when it really came down to it, the belts had become plenty strong.”

This illustration from Impact shows how a 3-inch belts rests in the all important iliac bone, compared to a narrower 2-inch.

The case for narrower webbing lies largely in the need to secure the driver as tightly as possible, and by analyzing the architecture of the human body, Impact made an interesting discovery.

“Because of the way that the human body is structured, the strongest part of the body is the hip area. That’s the area that when you want someone restrained in the vehicle, that’s where you want to place all the load. So getting the restraints as tight as possible is the number one criteria. And the way you do that is through brute force — pulling on the adjusters like crazy or even using ratchets — but one thing that makes it a lot easier to do this is decreasing the webbing size.”

Because there was this perception of 2-inches not being strong enough by a lot of sanctioning bodies, it took a big educational process to get them to even allow the 2-inch, let alone mandate them. – Ben O’Connor, Impact Racing

To illustrate this in the simplest of ways, if you cup your hand and take four fingers on your other hand and and lay them across your cupped hand and press down, you have to contort your fingers to get them to lay down in there. But if you remove a finger, your hand falls down into the cup much easier. In effect, you’re getting to a tighter fit, with less force, and you can get the restraints tighter.

To that end, a narrower belt also allows the restraints to get lower in the ilium, or the hip pocket. 

“This is important,” O’Connor says, “because in a forward event, you don’t want the pelvis tilting out from underneath you. You want to prevent this from happening, as this prevents lower back injuries.”

 

Likewise, you also don’t want the webbing coming over the top of the hip bone, known as the iliac crest — in a forward event — the webbing can ride up over the hip bone and get into the abdomen, leading to internal injuries. O’Connor says you never want to be restrained around the stomach; the lap belt should always be as low as possible, and as tight as possible, and a 2-inch belt accomplishes both much better than 3-inch.

O’Conner notes that the narrower belt also meshes (no pun intended) better with head and neck restraint (or frontal head restraint) devices, keeping them closer to the neck as the webbing narrows — this prevents sternum injuries, because the load is placed closer to the center mass of the chest. 

Without distorting the webbing as you tighten the belt, it is simply going to be tighter overall.

“And it turns out, they’re more comfortable. Drivers like that, too, especially in the tight confines of the cockpit they’re in,” O’Connor says.

Don Schumacher Racing’s stable of drivers, which includes Top Fuel’s Tony Schumacher, all rely on Impact’s 2-inch harnesses. The NHRA, at present, does not mandate one over the other in any of its categories.

Shoulder harnesses are less important than the hip area as it pertains to narrower belts, and while some drivers feel that wider webbing in the chest and shoulders will even the load more in a forward crash, O’Connor says “you will not notice a difference at all, and even in a crash event, there is nothing to suggest that one is more advantageous over the other in spreading the load. It just doesn’t play out.”

The SFI has maintained its 16.1 minimum standard for restraints for 40-plus years, so it took Impact and other manufacturers considerable effort to enact change derived from its foray into modern science.

Anybody that studies the science in how restraints work and how the human body works, it’s a no-brainer. – Ben O’Connor, Impact Racing

“Because there was this perception of 2-inches not being strong enough by a lot of sanctioning bodies, it took a big educational process to get them to even allow the 2-inch, let alone mandate them. So as a manufacturer, we felt this was so important to address the concerns of groups like NASCAR and others, that we went to the more stringent SFI 16.5, which pulls even harder on the webbing in testing, and also includes a micro-slip testing (a test for slipping through the adjusters). So NHRA and other sanctioning bodies now mandate that 2-inch belts meet that 16.5 standard — it’s to put everyone at ease that the belts are going to pass an even tougher standard than the 3-inch.”

Impact’s sales of 2-inch belts began to overshadow those of 3-inch over the last year, and O’Connor believes over the next couple of years, as buyers become educated on their benefits, the 3-inch belts will become obsolete. 

“Anybody that studies the science in how restraints work and how the human body works, it’s a no-brainer. You can’t even race in NASCAR now with a 3-inch restraint, and this needs to happen across the board.”

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About the author

Andrew Wolf

Andrew has been involved in motorsports from a very young age. Over the years, he has photographed several major auto racing events, sports, news journalism, portraiture, and everything in between. After working with the Power Automedia staff for some time on a freelance basis, Andrew joined the team in 2010.
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