Seatbelt lifespan? Are 20 y/o belts safe??

E36S50 · 05-12-2018, 12:52 PM

Track harnesses have date codes and lifespans which got me thinking - what happens when I get in an accident with my 20+ year old 911 seat belts? Is anyone aware of any tests or studies showing how old belts perform vs new belts?

Changing to new belts could be $400 very well spent

Trackrash · Trackrash's Garage

Good question. The owner's manual and PCA say that if there is no fading or fraying or accidents they are good.

Once upon a time PCA (Zone 8) would not let you on the track, even to autocross with seat belts over 20 years old. They have backed off on that rule.

The real debate is the 5 year rule on race harnesses. According to the manufactures nylon will loose about half its strength after five years.

mikl911 · 05-13-2018, 02:44 AM

I love that, "according to manufactures". Do you think they have any motivation to say that? Has an independent study ever been done or do we all just nod and an say ok here's my money?!? Not trolling, serious question.

Trackrash · Trackrash's Garage

There was a lot of debate when the five year rule was first put into place.

I think there are a number of factors to take into account. Nylon left unprotected in the sun will deteriorate. I have a surf rack that has totally fallen apart after a few years.

The question is, can't there be some way to protect against the suns rays, like my patio umbrella has?

And it's my understanding that car seat belts are made of polyester, not nylon.

On the other hand it's probably a good idea in a RACE CAR to change out the harnesses on a regular basis.

That still doesn't answer the question on cars seat belt age.

jons911 · jons911's Garage

On the point about nylon, it's not just in racing. The harness I use for rock climbing is a nylon web very similar to seat belts (at least from a visual inspection), and those also have a recommended life span of about 5 years.

rwest · rwest's Garage

This got me curious, so I did a bit of searching and came up pretty much empty handed. I would have though somebody on YouTube would have done a video on seeing what it took to break an old belt versus a new one- found nothing; maybe my search was flawed? Seems like somebody is testing anything for breakage on YouTube.

General google search came up with nothing that had a science type test behind it.

I think it would be a fairly simple thing to test if you had a rig that stressed something to breakage and recorded a number. Although maybe the force of slamming a body into a belt upon rapid deceleration is so great that you would need a lot of force to make a belt fail.

schoward · 05-13-2018, 11:42 AM

No studies but faded, fraying or inertia wheels not operating correctly = replace in my book. I did my dry, fraying fronts for $220 or so each for genuine porsche units if I recall maybe 10-15 years ago, and the peace of mind was money well spent. Garage kept with little sun and they still look and feel new. Did one side then another within a few months to spread the costs a bit. Always feel ok having my wife or daughter belt into the front which is nice. As a plus, when concours judges inspect my belts, I know I have a leg-up on the competition....

safe · safe's Garage

Quote:

Originally Posted by E36S50

Track harnesses have date codes and lifespans which got me thinking - what happens when I get in an accident with my 20+ year old 911 seat belts? Is anyone aware of any tests or studies showing how old belts perform vs new belts?

Changing to new belts could be $400 very well spent

Have you heard of anyone changing their seat belts for any other reason than wear?
Or better heard of any accident where the seat belts has failed? I haven't

The limit on race harnesses are probably there so they could sell more harnesses... I'm not saying that they are lying with the 50% less strength after 5 years, but how much strength is left?
I think the human body is the weak link, not the harness material.

E36S50 · 05-14-2018, 06:02 AM

Quote:

Originally Posted by safe

Have you heard of anyone changing their seat belts for any other reason than wear?
Or better heard of any accident where the seat belts has failed? I haven't

No I haven't but if old belts allow a lot more stretch in an accident vs new belts that could still mean they are a safety concern.

carreradpt · carreradpt's Garage

If the inertia reels fail to lock or release or is slow to, then that is a fairly obvious reason to replace your belts.

My seat belt saved my life in a 911 20 yrs ago. Glad they were in great shape.

Jesse16 · Jesse16's Garage

Seems like the proverbial can of worms that has no answer a manufacturer or race equipment manufacturer cares to ever comment on (lawyers). Simply far too many variables to know. You simply have to do what you feel is best for your peace of mind based on the info. you choose to believe. 5 years for new race harnesses, life-time for OEM belts or someplace in-between.

spedrcr · 05-14-2018, 04:06 PM

It's a great question with a myriad of answers. While you take the time to decide on replacement, consider soaking the belts in a simple green solution. Like dirt on paint, I would imagine that dirt and whatever else you can think of in the webbing of the belt will degrade the belt.

Check out the water after a three day soak of my drivers belt! 8 previous owners, targa and approx 140k miles. The water started out as a clear green. Ewwwww

KNS · 05-14-2018, 06:14 PM

I would think that if they’re kept out of the sun they should be replaced on condition unless they are truly ancient.

I was on an accident investigation of a Cessna 210 Centurian that had crashed in the mountains a while ago. I don’t know if the belts had ever been replaced (the last Cessna 210 was manufactured in the ‘80s) but I was amazed to see that some of the belts were intact but the anchor had ripped out of the aluminum sheet metal.

Superman · 05-14-2018, 06:55 PM

Quote:

Originally Posted by KNS

I would think that if they’re kept out of the sun they should be replaced on condition unless they are truly ancient.

I'd guess so. Considering the webbing, I think a seat belt could hold up a couple of cars rather easily. Not sure what their engineered breaking force is, but I'd guess it's mighty high.

I'm not sure I've ever heard a story of a healthy seat belt strap breaking in a collision.

TheSt|G · 05-15-2018, 03:37 AM

Given that most of our cars are 30+ years old, I would consider it prudent. It was the first thing I did when I got mine. Pretty cheap in the grand scheme of things, and seat belts are the #1 safety feature in accidents.

safe · safe's Garage

I feel an urge to find an ancient seat belt and rig it up in my 20 ton press....

Tippy · 05-15-2018, 04:16 AM

Curious if race belt manufacturers have any real data to backup the 'expiration' dates of said belts?

Bet there isn't....at least in the windows they claim are 'expired'....

If they did, wouldn't you think OEM's would have you change them at given intervals?

RedCoupe · 05-15-2018, 10:08 AM

In the summer of 2014 I was hit by a red light runner (distracted driver) that caused the 98 Chevy Lumina that I was driving to roll and wind up on its roof. This was my dad's old car and had very infrequent maintenance. Yet, the 16 year old belts and airbags worked perfectly and I didn't even get a scratch. Whether climate makes a difference, I don't know. Car had been garaged in a warm, dry climate.