Wise to replace slightly frayed seatbelt with used one from junkyard?
December 4, 2013 5:28 PM   Subscribe

2002 saab with 100,000 miles in generally good condition has a frayed driver's seat belt. To prevent further degradation, I covered the edge of the belt with duct tape. Frayed section conforms roughly in size to the concavity visible on the duct tape. Trusty mechanic quotes $175 + around $75 to install a junk yard replacement. This includes the entire assembly; trusty mechanic says they generally don't work well if you just replace the belt. A new belt and assembly is $475+ installation. I will have the opportunity to inspect the junk yard part before giving the go-ahead. Here's the question: assuming that it looks ok, am I better off from a safety stand-point with the used one of unknown history that in theory could be almost twenty years old or should I stick with my slightly frayed belt of known history (I bought the car new)? I know you are not my safety engineer! Thanks
posted by Kevin S to Home & Garden (9 answers total)
Obviously I-Am-Not-Your-Engineer, but this looks fine to me. The nylon is sewn so that each longitudinal strip is its own rope. It's like having lots of mini ropes that happen to be sewn to each other.

Here's an example of climbing harnesses being cut and tested: Black Diamond Belay Loop Test

I don't have time right now to find a seatbelt specific test but I'll continue looking later.
posted by just.good.enough at 5:42 PM on December 4, 2013

I wouldn't even bother to change it, I don't think it's dangerous as-is. I can't ever remember hearing of a car accident in which a seatbelt snapped, and I'm sure yours is far from the only worn one on the road.
posted by tylerkaraszewski at 5:46 PM on December 4, 2013

I would stick with the known-history belt. The prevention of fraying will last a long time.

An amazing thing I learned; Hondas have a lifetime warranty on seat belts and retractors. All you have to do is ask.

Saab's inability to provide parts or service is just one of the long list of reasons I scrapped my 2002 model 9-3 last summer. Every time I bought a we-promise-it's-a-genuine-part it turned out to be counterfeit.
posted by Kakkerlak at 5:48 PM on December 4, 2013

I'm an FAA certificated parachute rigger, so I have a fair amount of training and experience with webbing in safety-critical settings. If a parachute harness came to me with the same damage, I would ground it until it could be properly repaired. Damage to the edge can result in an instant 50% strength loss. If it was my car, I would replace the belt.

I should also note that in the parachute industry we strongly discourage using tape on webbing. The adhesive tends to collect grit from the environment, which is then ground into the webbing as it flexes and moves. Rather than protecting the webbing, it actually accelerates wear.
posted by indyz at 6:25 PM on December 4, 2013 [7 favorites]

Assuming that the new-to-you seatbelt is installed correctly, this is a great example of Looks Better; Is Better.
posted by oceanjesse at 7:17 PM on December 4, 2013

I very much doubt a seatbelt would be designed where edge fraying would cause very much strength failure.
posted by gjc at 12:28 AM on December 5, 2013

I have seen a lot of crashes, and a lot of them with cars with full safety harnesses. I have got in arguments with people that have told me "the belts are FINE" when they are frayed. It seems like the most ridiculous and stupid thing to shortcut and 'fudge-factor' over.

It's a seat belt. The only way you know for sure is that it will only fail and be an issue when it will be the deciding factor in whether your life is saved in an accident or not. If you (and the people in this thread) opining that it is fine are wrong, you probably won't be around to give feedback to that effect.

A frayed belt is a compromised belt, and that one has a fair sized chunk out of it. It is a purely safety item and so should be respected accordingly.

assuming that it looks ok, am I better off from a safety stand-point with the used one of unknown history that in theory could be almost twenty years old or should I stick with my slightly frayed belt of known history (I bought the car new)

You are always better with a non-frayed belt that looks to have no defects and not damaged by something else (fluids, burns etc). If the belt from the junkyard looks in better condition and has NO frays it is likely a better bet.

Is it worth saving $300 over by not buying a new one? Not in my opinion, no. Lose the frayed belt immediately and put a new one in.
posted by Brockles at 5:14 AM on December 5, 2013

the consensus seems to be to replace the thing.

i came in to say that if you do that, DEFINITELY replace the whole assembly. i had a car where we just replaced the belt and it stopped working just like the original belt. had we replaced the assembly, probably would have been fine (that was likely the problem to start with).

go with the junk yard one, but definitely take a look at it before it's installed.
posted by misanthropicsarah at 7:58 AM on December 5, 2013

Response by poster: Thanks very much everyone for your various responses. Unfortunately the two opposing views reflect rather accurately the within the brain battle I've been having about this. Being somewhat of a safety freak, my conclusion is to use the junk yard belt assuming that it is pristine, and otherwise to purchase a new one. Also, a little additional googling since I posted the question reveals that a frayed belt is an automatic failure in the annual vehicle inspection (though they haven't noticed it thus far).

Kakkrlak - Expect I'm also headed toward a replacement car, but would feel imprudent giving it up with a mere 100,000 miles - so maybe another year or so to go.

just.good.enough - interesting tests but with static loads. You've prob thought of this, but even the 5000 lb test could easily be briefly exceeded by high g's in a crash.

misanthropicssarah - definitely I'll look at it before installation. I confirmed with Truty Mechanic that he could return it without penalty.

Thanks again.
posted by Kevin S at 11:27 AM on December 5, 2013

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