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Bill Baer · 03-21-2011, 11:35 AM

The seat belt expration is based in some air force testing the shows a significant drop in the strength of nylon webbing when exposed tu UV light for a period of time (say 2 years or so).
While UV affects the neoprene in tires it's not as significant as it's affect on belts.

Per the S.F.I. :

"The rate at which the breaking strength of the webbing decreases with outdoor exposure is illustrated in the graph below. The webbing used in motorsports restraints is typically made with DuPont Nylon 6-6 or a similar product. According to the data, the webbing loses about half of its strength in one year. "

The Graph (not shown here) indicated ~20% stength after 24 months.

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

03-21-2011, 11:35 AM	#2
Bill Baer Senior Member Join Date: Jul 2007 Location: Nothern IL Posts: 596 Likes: 1 Liked 1 Time in 1 Post	Re: Why? The seat belt expration is based in some air force testing the shows a significant drop in the strength of nylon webbing when exposed tu UV light for a period of time (say 2 years or so). While UV affects the neoprene in tires it's not as significant as it's affect on belts. Per the S.F.I. : "The rate at which the breaking strength of the webbing decreases with outdoor exposure is illustrated in the graph below. The webbing used in motorsports restraints is typically made with DuPont Nylon 6-6 or a similar product. According to the data, the webbing loses about half of its strength in one year. " The Graph (not shown here) indicated ~20% stength after 24 months. Reference: http://www.sfifoundation.com/seatbelt.html __________________ Bill Baer 3391 SC, 339B SC, QR Last edited by Bill Baer; 03-21-2011 at 03:33 PM.