Racing is a dangerous sport . . . no kidding, right? But over the past decade or so it seems that advancements in safety equipment have made leaps and bounds. And these advancements have benefited one arena of oval track racing particularly well-Sprint Cars.
The power-to-weight ratio coupled with a high center of gravity make the Sprint Car a candidate for spectacular events when things go wrong. Their violent flips and tumbles consistently make sports highlight reels around the country. We have even heard local Dirt Late Model drivers espouse the fact that if they ever got into a Sprint Car they'd surely wear a head-and-neck restraint, even though they don't wear one in their own cars. To be truly safe in one of these cars takes diligence and a philosophy that safety begins not with a single component but a comprehensive cockpit safety system.
Everything in the cockpit must work in concert to protect the driver and not surprisingly, it begins with that car's foundation, the chassis. The goal is to combine predictable performance and driver safety into a complicated maze of aircraft-grade chrome-moly tubing, suspension, and drivetrain mounting points, a daunting challenge to say the least.
This picture shows the 2010...
This picture shows the 2010 chassis under construction. Veteran chassis builder Doug Shaw made several improvements to his tried and true design that yield a better, faster, and safer Sprint Car.
Doug Shaw has been building championship-winning Sprint Cars and open wheel racers for more than 30 years. His cars, like many other chassis builders', have been built around a standard design that goes back at least 40 years. As decades passed, new tweaks and changes to the design have made this "old school" race car platform perform even better. But Shaw upped the ante with his 2010 chassis by focusing on the ideology that all of the components of a cockpit safety system have to work together as one to be effective. Recently, he invited us along to take a look.
Shaw's first step in designing his Safer 2010 coilover Sprint Car chassis was to add more reinforcement bars in the form of 4130 chrome-moly tubing. He focused his improvements to the chassis' design on the seat frame and lap belt anchor area. New additions to the A-frame lateral bar reinforcement sets this design apart from conventional ones and, according to Shaw, these upgrades made a great difference in overall stability and safety for the driver without compromising performance and adjustability of the suspension.
He also added a lateral mid bar to the A-frame to reinforce the chassis against the torsional twisting forces when the car is under power. While the A-frame is a common part in all Sprint Car chassis and is the main rear support for the seat and structural rear cockpit uprights, Shaw's mid bar is a new addition.
The A-frame and seat supports...
The A-frame and seat supports are just two areas that received added attention from Shaw.
Based on previous experience, Shaw felt that this was an area that could use additional support in the event of an accident. To complement improvements in this area, inner seat rails were added to the lower seat frame. Newly designed lap belt anchors were welded to these rails. These changes form the foundation for a more comprehensive Sprint Car chassis cockpit safety system.
With the foundation design completed, attention could be turned to the seat. Weight of the seat has always been an issue with Sprint Car racers and previously, many lightweight Sprint Car racing seats were mass produced with little or no custom design, strength, or performance requirements. Full containment seats were naturally a great option but raised several questions from racers around the country including limited visibility out the right side of the race car, driver extrication in the event the car is upside down or against the wall, and their compatibility with head-and-neck restraints.
These potentially serious conditions led many track safety crews to lobby safety officials and equipment manufacturers to produce removable racing seats to make it easier to extricate the driver in the event of a serious injury. While conceptually interesting, removable seats are contrary to the design goals of a racing seat. In order for the seat to do its job, it must be securely mounted in the vehicle. Many believe that installing quick disconnect pins or mounts that can be easily accessed by the track safety crew is unrealistic due to the impact loads on the mechanism, the chassis, rollcage, seat, and driver compartment in a serious wreck. In addition, the driver still needs to be separated from the damaged seat for proper immobilization on a backboard and stretcher once he or she is removed from the vehicle-a difficult task sometimes even for experienced rescuers.
Enter Keith Grant and RSI Safety. "While working with ButlerBuilt, I developed a tool called the ZipFlex Wire Rescue Saw," explains Grant. The ZipFlex Wire Rescue Saw was designed to quickly remove the impact foam in the seat head surrounds to allow faster access to the driver by the track safety crew, in this instance without the initial need of powered rescue tools."
To lessen the chance of the...
To lessen the chance of the A-frame becoming damaged in a bad wreck, Shaw strengthened it and the belt mounts by continuing the middle A-frame lateral bar to the outer chassis upright.
The powdercoated chassis nears...
The powdercoated chassis nears completion.
The ZipFlex Wire Rescue Saw...
The ZipFlex Wire Rescue Saw was designed to quickly remove the impact foam in the seat head surrounds to allow faster access to the driver by the track safety crew without the need of powered rescue tools.
The ZipFlex uses a wire that...
The ZipFlex uses a wire that slices through the foam liner of the seat. You can see in this picture where the seat was retrofitted with the wire.
Grant then developed versatile ZipKits that could be pre-installed during new seat assembly or as an aftermarket retrofit. He says that they have been successful in many types of race vehicles and seats.
Grant, who has partnered with Shaw on the 2010 Safer Design Chassis says that the SFI Foundation has acknowledged the ZipFlex Wire Rescue Saw as one of the tools used for track safety crews in its Incident Response Training Program.
Shaw and Grant hooked up with ButlerBuilt to take a stock car-style full-containment seat and adapt it to his new Sprint Car chassis incorporating the ZipFlex system.
Of course, a great seat is only good if it's properly mounted. Shaw says that one of the main goals to mounting a seat properly begins before ever putting the seat in the car. First, you need to make sure the driver fits the seat properly and that the seat is designed for the type of race car it is being mounted in; Street Stock seats don't belong in a Sprint Car, Grant says.
The upper head surround flange...
The upper head surround flange will have to be notched to fit the upper A-frame correctly, especially if the seat is offset or reclined as was the case of this installation.
If you're moving a seat from one car to another, you need to visually inspect the seat for previous mounting holes, stress cracks, damage, or wear that could pose a problem in any potential accident. Plate, reinforce, and weld up any large holes that may tear or be unstable with the new mounting locations. Seats that have suffered serious crash impacts should be examined by the manufacturer for any structural defects needing corrective repairs. Make sure that the seat mounts and fasteners are separate from the seatbelt anchors. You don't want damage from one attachment point to compromise another part of your safety system.
Shaw and Grant developed an eight-point design plan for mounting a seat that, while designed for Sprint Cars, would work well in any chassis. As we have previously published in Circle Track, when mounting a seat you should only ever use properly sized Grade 8 bolts (5/16-inch) and always follow the seat manufacturer's recommendations for proper mounting.
The eight points used to mount the seat securely in this chassis are:
• Two manufacturer-supplied horseshoes around the lower seat bar at the bottom hip panels
• Two bolts through the front of the seat floor and the seat frame (with large washers and/or flat bar/plate support to reduce bolt pull through)
• Two bolts mid shoulder blade into the lower A-frame lateral bar
• Two manufacturer-supplied horseshoes on the head surround flange at the top of the A-frame
Here, you can see the manufacturer-supplied...
Here, you can see the manufacturer-supplied horseshoes on the head surround flange at the top of the A-frame.
The lower seat/pelvis, mid back, and upper head surround must be securely fixed to the chassis to prevent the seat from shifting, flexing, or becoming loose in the cockpit in a serious wreck.
Shaw is quick to point out that their findings show this to be the most secure method to mount a full containment seat in this Sprint Car. However, you need to know that changes or variations in your seat or chassis may prevent you from repeating this procedure exactly as outlined. He says to use common sense when installing a seat. In addition to the Grade 8 bolts, use large-bodied, high-strength flat washers to reduce fastener pull through, especially in aluminum components and contour or radius flat washers to match tubing diameter. Use locknuts whenever possible to reduce the tendencies of fasteners loosening in critical areas. Avoid lightening brackets and supports at all times. They are there for a purpose and your life may depend on the seat performing as designed and should not be modified.
Once the seat was in place, Shaw and crew turned their attention to the harness. For this car, they opted for six-point belts from Hooker Harness. Hooker builds safety harnesses for all types of aircraft, from sport and stunt planes to military applications, as well as all types of race vehicles. Its belts feature a special ratchet tensioner that the company says reduces the likelihood of belts loosening up during a race. Like the seat, a great set of belts won't do you any good unless they are properly mounted. And again this is an area where Shaw's new chassis shines.
For years, most drivers and chassis builders have wrapped their lap belt anchor ends around the outer chassis rail next to their seat mounts. It was the easiest way to connect the lap belt to the strongest part of the chassis and seat mount frame. Few chassis builders provide a chassis mount or tab close enough to the seat for the bolt through lap belt anchors to be effective.
Here you can see the old way...
Here you can see the old way of wrapping the belts around the chassis next to the old-style shear brackets.
For the 2010 design, Shaw...
For the 2010 design, Shaw went to new 30-degree offset brackets that would be more resistant to shear at the chassis. The angle puts the belt loading path directly in the center of the bracket rather than the 90-degree straight up bracket (center) first used in an earlier design.
This angle shows the extra...
This angle shows the extra beefiness of the double shear bracket.
It's critical to that you...
It's critical to that you have the correct lap belt mounts for these new double shear brackets, so check with your belt manufacturer. Shaw TIG welds the brackets in specific locations based upon the mounting of the seat.
Loose lap belts also reduce the ability of the shoulder belts to remain in their respective position to control the upper body motion properly in a wreck. Wraparound belts also have a tendency to slide on the seat rail, sometimes under a load, unless they are secured in place to prevent lateral movement. Serious injuries to the abdomen, groin, and upper thigh area are all a result of improper belt placement and anchoring of the lap belts. The resulting load angle pulls either too low on the hips and thighs or too high on the abdomen.
In addition, certain head-and-neck restraint systems (HNS) depend upon the shoulder belts doing their job and holding the HNS in place. If the belts move, the HNS moves out of its design parameters and consequently, needless injuries occur.
Military tests on fighter pilots have proven that in order to best protect the pilot in an impact or through their g rolls and maneuvers, the aviator's pelvis had to stay put in the seat. Race car drivers are no different.
Keith Grant of RSI Safety...
Keith Grant of RSI Safety stands next to the 2010 Safer Chassis.
Sled tests performed at several top research universities in the areas of motorsports restraint performance, HNS, and full-containment seats delivered the same results as the military tests; the only way to properly keep the driver in the seat is to make sure the pelvis stays put in that seat.
When the pelvis stays locked in the seat, the body is then able to absorb more of the impact load, then control and dissipate that energy. Less bodily injury occurs with the properly mounted full-containment seat, HNS, and driver safety equipment working together as a comprehensive system.
During the construction of the new Shaw Safer Design coilover chassis, Shaw and Grant decided to use double shear brackets instead of wrapping the lap belt anchor point. Double shear brackets utilize a U-shaped steel bracket with two equal legs, through which the belt anchor is bolted. These brackets utilize a Grade 8 bolt and locknut with a sleeve spacer separating each leg of the bracket. This design allows the bracket legs to be tightened against the sleeve, allowing the belt anchor to pivot and self adjust to the load as needed with no restriction. A double shear-style bracket can also prevent belt dumping from occurring. However, they must be properly located to do so.
With the help of A&A Manufacturing, Shaw and Grant designed a new double shear bracket to reflect a 30-degree offset pin location to compensate for the load path the new lap belts and ratchet tensioner would take in their proper mounting place on the chassis.
This picture shows how Shaw...
This picture shows how Shaw used A&A Manufacturing's double shear weld-on brackets to mount the Hooker Harness ratchet tensioner assembly on this Sprint Car chassis. He also added a secondary inner seat-mount rail to the standard seat frame on both sides for the narrower seat. This rail size was increased for more support over the earlier 2009 design.
Shaw's new design puts the lap belts at the proper angle to secure the pelvis in the right points as indicated in crash sled testing. With the pelvis secured, it was now onto the upper body.
For years, shoulder belts have been mounted on the rear lower chassis cross rail for strength and ease of mounting.
Most belt and seat manufacturers suggest that the shoulder belts' anchors should be approximately 10 degrees below the plane of the top of the shoulder or clavicle area. That horizontal anchor point translates to approximately 1 inch below the top of the shoulder or clavicle area where the shoulder belt contacts that area.
In a Sprint Car application, the lateral A-frame bar provides a directional change equivalent to the 1-inch lower anchor mounting point. Initially, Shaw and Grant attempted to mount the shoulder belts directly to the seat bar, but, because of the close proximity to the seat and the awkward mounting angle, the belts could not be wrapped properly to keep the three-bar adjuster from protruding through the shoulder belt holes. This problem could possibly injure the driver's neck or head in an accident or interfere with the HNS, so they chose to use the lower A-frame bar as the alternate anchor mount.
What they did find during their research was; that to lessen the chance of the A-frame becoming damaged in a bad wreck, they strengthened the A-frame and the belt mounts by continuing the middle A-frame lateral bar to the outer chassis upright to provide an increased level of safety. Shaw began implementing this new change in all his new Sprint Car chassis starting in 2010.
Shaw's new safer design has already won four races in Florida Top Gun Sprint Series, proving that a safer Sprint Car chassis can also be a stronger, faster Sprint Car chassis.
Here you can see how the properly...
Here you can see how the properly mounted belts pass over the middle A-frame lateral bar horizontally.
The new 30-degree double shear...
The new 30-degree double shear bracket is shown next to the 2009 version on an older chassis.
Shaw shimmed the bottom of...
Shaw shimmed the bottom of the seat to prevent any abrasion problems from damaging the submarine belt. The driver of this car wanted the seat reclined a bit, which brought the mounting point of the anti-sub beltaa little farther back than Shaw wanted, but he says it's still in a good location for the belts to be effective.