If you’ve ever taken a close-up look at a race bike, you may have seen coils of twisted wire wrapping around a lot of the fasteners, especially around the brakes, suspension, and axles. That stuff is called safety wire, and it’s not just for racers – it’s for any rider! In this article, we’ll tell you what it does, why it’s there, and then give you a quick how-to on installing it on your own bike.
What’s The Point Of Using Safety Wire?
Safety wire is installed as an additional measure of protection to keep critical fasteners in place when being punished by hard use from vibration. Vibration from engines and from the road is constantly at work to slowly loosen your fasteners until they back out and eventually fall off your bike, and at high RPMS and speeds – like those seen in racing or track duty – this actually happens a lot more often than you think! Almost every motorcycle racing organization, and even some track day organizations, require some level of safety wiring in order to participate.
But you’re probably thinking “I don’t race or own a race bike, so why should I care?” Well, if you think about it, safety wiring can be just as important on the street as on the track. Fasteners can vibrate loose anywhere, and a caliper bolt or oil drain plug coming out would be just as bad on a canyon or mountain road as it would be on a race track. (Actually, it would be worse, because the streets are a lot more dangerous, and there is nobody around to help you if you crash!)
And safety wiring is not just a racing thing either – it’s used a lot anywhere it is absolutely critical for fasteners to stay in place, so it’s a practice you see a lot in aviation, heavy industry, and marine applications. Anywhere you can think of where a bolt really needs to stay put under stress, safety wire can be used to make sure it does.
Safety wiring isn’t just used in motorsports racing – it’s used in any application where it’s absolutely critical for fasteners to stay put, such as aviation, marine, and heavy industry. Here, a Navy sailor installs safety wire on the landing gear of an aircraft.
So you don’t need to be a racer to benefit from safety wiring at all. While safety wiring every bolt on your street bike might be overkill, it’s not unheard of at all to safety wire a few critical fasteners, even on bikes that never see track duty. It’s pretty easy to do, and gives you additional peace of mind that your bike will hold together where you need it to. (Plus it just looks cool!)
How Does Safety Wiring Work?
Safety wire is used to put tension on a fastener to make it impossible for it to back out, and it is used on any fastener that would adversely affect safe handling or operation of a motorcycle if it were to come loose. Any fastener can vibrate loose (and if you’ve been riding long enough, you’ve seen a few go missing on a ride!) But if a fairing screw falls out, it’s no big deal; on the other hand, if your oil drain plug falls out, it will be very bad news for you (and anyone riding behind you.) For this reason, any fastener with fluids behind them are typically safety wired (like oil and coolant drain plugs), along with caliper bolts, axle pinch bolts, and axle nuts.
In addition, safety wire creates a visual indicator for everyone to see that a fastener has been torqued to spec and is good to go. During a tech inspection before a race, inspectors can easily recognize which bolts are fastened in place if they are safety wired, whereas at track days, where little or no safety wiring is required, a bike can go on track with a loose fastener that the operator may have forgotten to tighten.
Here you can see safety wire installed on a motorcycle’s caliper bolts.
The same logic can apply to your garage; if you have certain fasteners safety wired, you’ll be able to double check that everything is torqued to spec during the safety wiring process. This may sound like overkill, but almost everyone has forgotten to tighten some nut or bolt at some point in time (I know I have) and this eliminates that risk.
How to Safety Wire Fasteners
The logic behind safety wiring is to do it in a way that creates tension that prevents the fastener from being able to back out. If it is a single fastener, the safety wire can be run to an anchor point of your choosing. If two fasteners are being safety wired, they should be wired in a way that if one comes loose, it would tighten the other one, and vice versa (see illustrations.)
This illustration shows how proper safety wire is installed – in a manner that, if one bolt were to come loose, it would tighten the other, and vice versa.
There is a trick to twisting the wire and using safety wire pliers (which you can see in our Garage Video, How To Safety Wire a Motorcycle) but that’s actually not the hard part; the hard part is drilling the holes in fasteners for the wire to go through! Most fasteners are made of hardened steel, and the holes you will be making are very small and at challenging angles, so it can be a frustrating process.
If possible, the best way to safety wire is to replace your fasteners with ones that are pre-drilled for safety wire. Otherwise, if you will be drilling them yourself, get a hold of a drilling jig in order to hold the fastener in place, and guide the drill bit into it at the right angle. In addition, you’ll want to do this with good quality titanium or cobalt drill bits – drilling through hardened steel will wreck normal drill bits in a hurry, and make this project become very frustrating!
Once you’ve gotten past the hard part of drilling your fasteners, the process of actually safety wiring is relatively easy. Safety wire is typically 0.025-0.032″ (the former being more pliable and easier to work with, the latter being stronger) and all you need to do is thread it through the hole in the fastener, and twist it tight as seen in the diagrams. You can do this with needlenose pliers, but a pair of dedicated safety wire pliers will get the job done a lot faster because they actually twist the wire for you.
Check out this video for a quick visual explanation of how safety wire is installed!
For your reference, here are the steps in order:
- Drill fasteners, or install ones with drilled heads
- Loop through the fastener in a direction that pulling on wire would tighten the fastener
- Twist with safety wire pliers (or needlenose pliers – more labor intensive, but it works)
- Stop a little short of next bolt or anchor point, and make last twist by hand to get it to the perfect length
- Go into the opposite side of other fastener
- Tighten up second fastener with several twists
- Snip off end of pigtail and tuck in (snipped ends are needle sharp, and if you don’t tuck them in they will snag or puncture your skin or gear!)
- Collect snipped part and throw in trash (if not, it essentially becomes a needle waiting to pierce a tire if left on the ground!)
That’s basically all there is to it! Safety wiring is tedious, but not difficult at all, and it’s the kind of thing you’ll get the hang of after just doing two or three fasteners. Give it a try!