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SSDiv6 · 05-18-2013, 02:40 PM

[QUOTE=Greenlight;381934]Sammy, the OEM seat belts (~1.8" -2.0" wide) have a minimum break requirement of 6000 lbs. and must retain at least 60% of that strength (3600 lbs.) after long term exposure to radiation (i.e. 20 years), etc. (see FMVSS # 209). For a 220 lb. driver (95% percentile), the 20 year old seat belt can withstand about 17g (maybe a 60 mph crash in a modern car).

The attachments (metal portions) each must withstand at least 2500 lbs. (during a crash the seat belt takes the entire load, while the load is distributed to several hardware points.
Generally speaking, the hardware maintains its strength for more than 20 years. That's why you could pick up the 20 year old car by the seat belt.

Racing seat belts are wider and the racer is exposed to more seat belt area (3" wide, 5 pt.), which is very good in distributing the load to the driver during an impact (maybe a 60g impact). The problem, as I see it, is the SFI spec. indicates that the common material used in "racing" seat belts (Dupont Nylon 6-6) maintains only 60% of its strength after 1 years exposure to radiation, and may only retain 10% of their strength after only 2 years of exposure to the elements. This is what I find unbelievable.

http://www.sfifoundation.com/seatbelt.html

If the SFI spec. required manufacturers to use OEM type material (probably slightly more expensive) the seat belt recertification time could be extended, but the manufacturers would make less $$$ (you always have to follow the $$ trail).QUOTE]

About 10 years ago, I had a discussion with SFI on this subject with enough criteria for extending the expiration requirements for Sportsman racers. I provided actual testing results on seat belts performed under the DOT standards with additional analysis that was extrapolated to expected motorsports and racing forces during a crash and additional studies based on published SAE papers. Guess what? They did not care.

If SFI changed the belt material specifications, it will not increase the cost of the belts. You can procure 660 feet of belt webbing that exceeds both the DOT and SFI requirements for around $150.00. The cost of the belt is in the fabrication and manufacturing.

05-18-2013, 02:40 PM	#10
SSDiv6 VIP Member Join Date: Feb 2003 Location: Glendale, Arizona Posts: 3,044 Likes: 712 Liked 1,580 Times in 582 Posts	Re: Racer Suspension [QUOTE=Greenlight;381934]Sammy, the OEM seat belts (~1.8" -2.0" wide) have a minimum break requirement of 6000 lbs. and must retain at least 60% of that strength (3600 lbs.) after long term exposure to radiation (i.e. 20 years), etc. (see FMVSS # 209). For a 220 lb. driver (95% percentile), the 20 year old seat belt can withstand about 17g (maybe a 60 mph crash in a modern car). The attachments (metal portions) each must withstand at least 2500 lbs. (during a crash the seat belt takes the entire load, while the load is distributed to several hardware points. Generally speaking, the hardware maintains its strength for more than 20 years. That's why you could pick up the 20 year old car by the seat belt. Racing seat belts are wider and the racer is exposed to more seat belt area (3" wide, 5 pt.), which is very good in distributing the load to the driver during an impact (maybe a 60g impact). The problem, as I see it, is the SFI spec. indicates that the common material used in "racing" seat belts (Dupont Nylon 6-6) maintains only 60% of its strength after 1 years exposure to radiation, and may only retain 10% of their strength after only 2 years of exposure to the elements. This is what I find unbelievable. http://www.sfifoundation.com/seatbelt.html If the SFI spec. required manufacturers to use OEM type material (probably slightly more expensive) the seat belt recertification time could be extended, but the manufacturers would make less $$$ (you always have to follow the $$ trail).QUOTE] About 10 years ago, I had a discussion with SFI on this subject with enough criteria for extending the expiration requirements for Sportsman racers. I provided actual testing results on seat belts performed under the DOT standards with additional analysis that was extrapolated to expected motorsports and racing forces during a crash and additional studies based on published SAE papers. Guess what? They did not care. If SFI changed the belt material specifications, it will not increase the cost of the belts. You can procure 660 feet of belt webbing that exceeds both the DOT and SFI requirements for around $150.00. The cost of the belt is in the fabrication and manufacturing.