Racer Suspension

[Greenlight]

Originally Posted by sammy pizzolato

evan you missed my point. my point is that if a 20 year stock seat belt half the width half the thickness will hold up a car. a two year old race belt can't be bad in two years.the two year rule on seat belts should be every five years at the least.there is no way that a racing belt should go bad in two years.my good friend owns a wire rope co he has a tester.we tested a ten year old racing belt and the metal hardware broke and the belt never broke. and jeff teuton had him test it.

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).

Of course, none of us throw our seat belts out in the sun between races (unless we find out that David Rampy is doing it to gain a competitive advantage, then you would see Sun-dried seat belts for sale for $1000s on Racing Junk), so the 3" wide webbing will likely be stronger than the metal components even after 10 years. Hence the hardware breaking in your 10 year old seat belt test.

As I recall, the webbing failed (or the sewing) in Lee Shephard's crash in 1985, which prompted the seat belt rules being what they are today.