Safety Lock Wire - Safety Wiring: It Ain't Rocket Science

Safety wiring bolts came into use about 50 years ago. Mechanics wired bolts together so propellers wouldn't fall off airplanes. The same principle holds true today. We don't want parts to fall off race cars, some of which are going faster than the planes did long ago.

The teams on the top rungs of our sport safety-wire everything. It is a quick way to visually inspect the car before a race. If the wire is there, everything is tight. When installed correctly, the safety wire limits the ability of the bolt to rotate and loosen. What parts do you safety-wire? Everything that does not have to be removed quickly in a pit stop. Safety-wire anything that is not removed after every race. A partial list would include header bolts, fan-attachment bolts, drain plugs, starter bolts, and all brake-component retaining bolts for the calipers and rotors. Other components that require safety wiring are the differential bolts, driveline bolts, suspension bolts, and all hardware for the steering.

Hole In The Head
There must be a hole in the head of the bolt in which to attach the wire. Most aircraft hardware already has the hole drilled in the head. If there is no hole, you can drill it yourself. Several companies make jigs for drilling holes in bolts. The jig can handle different-size bolts. It holds the bolt steady and guides the drill to the proper place on the bolt head to drill. The hole should be about 3/32 inch. Drill at a slow speed with a cobalt drill bit, lubricating constantly. When you finish drilling through the head, deburr and chamfer the sides of the hole. Sharp edges will notch the wire and cause it to fail.

Start Here
The first step is to tighten the bolt to its proper torque. Next, cut the wire long enough so that it can connect the bolt to a fixed point. It can be another bolt or a fixed point on the race car. Safety wire is cheap-don't be stingy with it.

Put the wire through the hole and loop it around the bolt head in the direction that tightens the bolt. Do not lay it over the head of the bolt. Pull the wire tight with locking safety-wire pliers. The pliers will spin, twisting the wire. Do not twist the wire so tight that it breaks. About 10 turns per inch is enough. Twist the wire to within a quarter inch of the second bolt or the point used to tie down the end of the wire. Insert the wire through the hole in the same direction as before, and twist the wire again. Leave about 1/2 inch past the termination point, and cut the wire. Bend the sharp edge of the wire in, onto itself. This way, you will not scrape your hand while working on the car.

Safety-wiring your car is something you know you should do, but don't. It is the same as knowing you should torque every bolt, but don't. It takes a little extra time, but it saves time when you nut and bolt the car before the race. It also gives you peace of mind knowing that parts are not going to fall off the car.

What You'll Need
Safety wire pliers, the bolt jig, and safety wire are available from many suppliers. There is no substitute for safety-wire pliers. They cut the installation time by 90 percent. Use MILSPEC 20995, type 302, stainless steel wire that is 0.032-inch diameter. It is softer and more malleable than carbon or alloy steel.