Are 2-Inch Lap Restraints Safer Than 3-Inch Lap Belts?

Are 2-Inch Lap Restraints Safer Than 3-Inch Lap Belts?

When the mention of restraints enters the conversation, everyone conjures up a different mental picture. Some will envision the artwork from Quiet Riot’s Metal Health album of the 5150 dude in a straight jacket and metal face mask. Others will visualize Mistress Helga in leather thigh highs with a riding crop, handcuffs, and chains. In the case of most dirt track racers, the image of web strap restraints that bind them safely in their racing seat is most often the image which comes to mind.

[Ed note: 5150 is the California law code for the temporary, involuntary psychiatric commitment of individuals who present a danger to themselves or others due to signs of mental illness]

Racing restraints are offered in either 2-inch or the traditional 3-inch widths. Modern technology and manufacturing has shown that 2-inch wide restraints actually do a better job restraining racers in a violent collision. This is due to a better fit to the racer’s anatomy.

For racers, seat restraints are one of the earliest forms of safety in motorsports. The goal of the driver restraint assembly is to keep the driver inside the rollcage where the least amount of injury will occur in a crash. No one can actually say when the first restraint was used in racing, but experts speculate that after WWII surplus aircraft belts were utilized by a few racers trying to protect themselves. That puts racing restraints in the sport for close to 75 years.

You can’t even run a 3-inch in NASCAR’s top classes. Don’t even show up with them! That is how important they feel it is. – Ben O’Connor, Impact Racing

Not only are restraints one of the oldest forms of racing safety, they are also one of the most evolving pieces of safety equipment. The industry is always learning new things – not just about the belts – but the physiology of human bodies, how restraints fit on people, and what happens during a crash. The safety equipment manufacturers take all the information learned and apply it to restraints with the goal of building better containment and restraints. To get a better idea how the companies who make these life-saving devices help protect racers, we reached out to Vice President of Sales Ben O’Connor, at Impact Racing, Inc.

A Word About Restraints

A restraint assembly consists of several components, each with a specific function. The shoulder harness is a belt assembly, one strap for each shoulder, intended to restrain movement of the upper torso and shoulder regions. An optional cross strap across the chest can be used to hold the shoulder harness together. The lap belt restrains movement of the pelvis and the anti-submarine strap prevents the pelvis from slipping forward under the lap belt in the event of an accident.

The Pros and Cons of the Latch and Link buckle system.

The buckle which attaches the belts together should have a quick-and-easy release mechanism in the case of an emergency situation. According to O’Connor, “There are three types of buckles to choose from: latch/lever, turn/push, and cam-lock. All three can be opened in 1 or 2 motions.”

The pros and cons of the Cam-lock buckle system.

“A restraint assembly also utilizes two types of hardware,” O’Connor says. “The adjustment hardware is used to alter the length of the individual straps to fit the driver. Mounting hardware secures each strap to the vehicle.”

Exposure and degeneration of nylon webbing over time.

Restraints must be maintained, inspected, and replaced or re-webbed every two years because they degenerate over time and from exposure to the elements. “Prolonged exposure of seat-belt webbing and thread to sunlight can cause degradation of the fibers and loss of restraint integrity,” he added. With this kind of deterioration, it is obvious why the SFI Foundation (SFI) requires replacing the webbing every two years for driver safety.

“As cars become more advanced and consequently go faster, everything possible must be done to make the racing experience safe as well as fun. Failure to do so can cause serious injury, or worse,” Ben says.

If there is anything to be learned from the sport of racing, it’s that anything is possible, and taking the attitude of “it won’t happen to me” is risky, because it can and does happen.

Lap Belts And Anatomy

Since the five-point harness was adopted from military applications, it was better than what was previously used, which was a standard car seat belt or none at all. “These restraints were always three-inches wide, because back in those days they needed the strength of the webbing to withstand the forces of the pull in an accident. These days, the textile industry has advanced so far and the webbing is so much stronger than what it used to be,” O’Connor explained. 

“Virtually all the testing safety organizations do, SFI and even FIA, support the fact the harness hardware will probably fail before the webbing will. That is just the way it is today, the strength is not an issue anymore if you are using good polyester-based webbing.”

According to O’Connor, “when you are running a 3-inch restraint, there is a void the webbing has to contort to in order to fit down into the hip pocket. With a 2-inch restraint, the width allows the webbing to sit into that pocket easier. This means it sits closer to your body, which means you can get the restraint tighter.” In theory, keeping the driver restrained tighter in the seat is the best way to prevent injuries. 

O’Connor claims there is another size aspect which plays a part as well. “The 3-inch restraints will sit on the top of your hip bone, the iliac crest. This makes it difficult to get the restraints as tight as they need to be. More importantly, these can move up, and in the event of a crash, they can get above the hip bones and into your abdomen causing internal injuries. The idea is to keep the belt low and down in the pocket all the time. Because the 2-inch belt sits in the pocket area better, there is less chance of internal damage due to the belt riding up.”

All three NASCAR divisions mandate 2-inch lap harnesses. “You can’t even run a 3-inch in NASCAR’s top classes. Don’t even show up with them,” said O’Connor. “That is how important they feel it is.”

SFI dating on restraints.

Proper installation of the restraint assembly also means achieving the correct fit to the driver. SFI has published a Seatbelt Installation Guide for motorsports vehicles with upright seating. This guide can be used to help determine the optimum installation angles for lap belts, shoulder belts, and crotch belts. You can download the guide by clicking here: SFI Seatbelt Installation Guide.

SFI dating on lap restraints.

Always follow the installation instructions provided by the seat belt manufacturer, as well as sanctioning body rules. Also, the necessity of replacing or re-webbing seat belts every two years cannot be more important.

For more information on driver safety equipment, please visit Impact Racing Products online at or call them at (317) 852-3067.

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