No matter what type of vehicle...
No matter what type of vehicle you are driving, you should inspect your seatbelts after each race weekend to look for cuts and frayed ends on the belts. If you find either, you should replace your belts immediately. Photo by John Gibson
Simpson Race Products has also tested and uses polyester. As a result of their testing, they have published some rather amazing stats. One of the most impressive is that at 2,500 pounds of force, nylon belts will elongate (stretch) 15-17 percent their normal length. The elongation on polyester at the same amount of force is only 7-9 percent. Further, the nylon webbing has a tendency to absorb water, and when it gets wet it loses some of its strength, approximately 12 percent. However, Simpson's testing concluded that belts made primarily of polyester webbing lost no strength when exposed to water. This is the reason that Simpson is currently manufacturing two different sets of polyester belts, the most popular being the platinum-style safety belt.
Polyester's strength and durability is the primary reason German harness maker Schroth Racing Harnesses have always used it in their harnesses. Schroth harnesses offer a unique "memory effect" designed into their webbing. Special mono filaments laterally woven in perform like small leaf springs and keep the webbing flat. This results in better load spreading over the full width of the webbing. Another benefit of the Schroth webbing, the special weaving technology forms round edges for additional comfort.
These are Simpson's Platinum...
These are Simpson's Platinum series seatbelts. These belts (like other manufacturers) are made out of polyester webbing. Polyester is stronger and more durable then the older nylon belts. Photo by Jeff Huneycutt
Of course, all of the design and safety ratings of the seatbelts are useless if the belts are not properly installed on the chassis. We won't go completely into every step on how to mount your seatbelts correctly here, because that would be another article entirely (see "Anchor In," December 2007). But I do want to highlight just a few areas. Never mount any seatbelt bracket to the sheetmetal floorboard, and always use Grade 8 bolts when attaching the seatbelts to the chassis. Make certain that the lap belt is not too high; it should be mounted so that it latches where your belt buckle would normally rest.
Teams tend to forget that the main purpose of the seatbelts is to keep your body from moving forward during an accident. But one of their other main purposes is to keep your body from moving down during a hard collision. This is why it is hard to find anyone running a simple four-point harness anymore. A five- or six-point harness is now the way to go. If you really want to take the next step, several companies, such as G-Force Racing Gear, actually manufacture a seven-point harness as well.
This might sound like a bit of overkill, but you should be inspecting your belts after every race weekend. Chances are you're going to be cleaning out the inside of your car, so why not do a quick safety check of the belts at the same time? This is especially true if you were involved in an accident. The first thing you should check for is any tears or cuts in the seatbelts. Like we stated earlier, your belts will actually stretch during an accident, so make certain that there are no nicks or cuts in those belts.
Here is Schroth's six-point...
Here is Schroth's six-point harness, notice the webbing detail on the belt. Seatbelts are woven in a way that increases their strength. NASCAR rulebooks say that the belts must be able to hold an incredible 15,000 pounds of dead weight. Photo by John Gibson
You should also check for any type of fraying that might be occurring on the belt. This will significantly reduce the strength of the belt. The woven pattern of the seatbelts will help prevent this fraying but it can still happen. Usually, it will start out as a small cut and then it will fray the edges over time. If they start to become frayed, then it's time to replace the belts.
One of the other things you need to inspect is your mounting brackets. You can avoid doing this every week, but after any type of accident always pull the Grade 8 bolt out and inspect it for any bends and look at the bracket itself to ensure it has no bends or warps in it. If either has been compromised, then you should replace them before the next race. It all comes back to not settling for faulty equipment.
I will admit that I have been guilty of running aged belts as well, but most sanctioning bodies are now cracking down on teams doing this. You should replace your belts every two years and definitely sooner if you discover any type of cuts or fraying. The SFI safety rating makes it extremely difficult to even get around the safety inspection at your local racetrack anymore.