Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Lack of Locking Wires in Automobiles

How come automobiles don’t use locking wires on fasteners? It would seem to me that several of the fasteners are safety critical. If the nut or bolt comes loose as a result of vibrations, then it could put the driver’s life at risk or destroy the car. Why are locking wires not use as a risk mitigation of this issue?

John , you worry way too much .


I’ve wondered the same thing too, as an airplane owner.
Oil filters, fasteners which hold propellers on, oil filler tubes, control cable turnbuckles, etc. are all wired "we call them “safety wires”.
The safety wires have to be taught, and to do this one uses a safety wire “twister”, which twists the wires and creates tension.

Many critical automotive fasteners, such as for suspension and steering components, used to use castellated nuts with cotter pins for retention. Maybe many still do, or they use the prevailing torque-type nuts (the ones that are slightly squished to provide a tight thread fit). It seems many aftermarket replacement parts nowadays just use the cheap nylock nuts instead. I always use threadlocker on critical fasteners.

Such failures almost never happen when fasteners are torqued properly. Also, thread locker is used on some of them.

Online or do they have to attend classes? :upside_down_face:


Given the almost complete lack of problems related to properly-torqued fasteners, this would be a huge waste of money and time.

1 Like

My 1999 Honda has castle nuts and cotter pins at the ball joint. The nut at the end of the front axles is brought up to torque and then staked. There may be other such - those are ones I recall right away, from DIY work.

Because they are an added expense and a labor intensive perfect solution to a problem that does not exist.

It’s the same reason why I don’t apply elephant repellent around my car’s parking spot.
:palm_tree: :sunglasses: :palm_tree:


When something falls off an airplane, it usually falls out of the sky.

Not so with a vehicle.


1 Like

Because they are MASSIVELY time consuming and expensive to build cars like this. $50,000 car… $500,000 aircraft. Get it?

Many suspension parts that used to have cotter pins no longer do. Why? Because there are a ton of fasteners that can prevent loosening in a variety of ways that can be hammered on with electric torque measuring drivers and sent on their way.

Nyloc nuts, for example. Prevailing torque nuts with the last couple of thread distorted to grip the stud. Flange nuts that bite into the mating part so they won’t loosen. Grippy washers that do the biting. And the many, many variations of Loctite (and other brand) chemical threadlockers that are applied dry on nuts and bolts so they activate when installed.

There is no need for safety wire. That is very old technology as are many things in the aviation world.

1 Like

Because the problem it addresses is a non-issue.

Also because there are much more effective, efficient, and economical ways to accomplish what the locking wire does.

I do recall seeing (and using) locking wires on certain British cars from the 50’s and 60’s. If 60 year old British automotive technology is something to aspire to today, then we need to examine priorities…


Are you saying I have been wasting money ?


I don’t think so, elephant repellent has kept them off my car. But the neighborhood cats seem to be attracted to it.


The cat’s are attracted to it becauset they don’t have to fight the elephant’s off.



Would you want a dumb safety wire.? Really?

I don’t think I could PAY a pilot to fly my Piper Seneca if the safety wires were removed from the oil filters on its engines.
On the 727’s I used to fly, the Pneumatic brake handles (used in event of hydraulic failure )in front of the Captain had to be safety wired,to prevent the handle from accidentally getting moved in flight.
I’ve read at least one post here about someone’s oil filter possibly coming loose. That wouldn’t happen on an aviation filter.

As far as the person who claims that aviation practices are outdated, I sure hope he doesn’t work in the field.

1 Like

That’s where I got the idea from. I know they are used in airplanes all the time. Although I’ve never heard of them called safety wires before. It was just an interesting question I had, as far as why are they not used in automobiles, and I figured I would ask. I get that it’s a $500,000 plane vs like a $20,000 car, but it seems like in both cases people’s life’s are in hands. It would make sense that non-safety critical fasteners wouldn’t need them. But I guess it’s just not an issue for automobiles. I guess they don’t vibrate as much.

That, and the consequences are so much less.

The reason I say that aviation technology, not practices, are outdated is the amount of certification required to get FAA approval means that new techology is too expensive for many manufacturers to get approved for private aviation. It will be up to the military to push that technology ball forward and pay for the qualification testing.

As for flying without safety wire… the FAA would pull his license if he knew they were missing and he flew anyway.

Edit: Your Piper Seneca was designed in the late 60s and was first sold in 1971. How old is the car you are driving? How much do you think has technology advanced in the years between when your aircraft was built and your car was built?

1 Like

Yeah used on space shuttles, missile launchers, air craft, etc. Cost and consequences. It’s a car, not a fighter jet, and I have yet to have a factory fastener come loose. (I’ve had my own fastener come loose once, but nothing the factory did.)