Safety First: Safety Wire

Click Here to Begin Slideshow In several past issues, we took a detailed look at aircraft fasteners. If you recall, several of the fasteners are designed to be safety wired. Aviation isn’t the only place you’ll find safety wired fasteners. Many road racers safety wire things like fasteners for ball joints, brake hardware and so on. These are important products, but we won’t go into what parts need to be safety-wired. Instead, what follows is the right way to use safety wire: There are good reasons why safety wire is used on aircraft, race cars and race motorcycles. The first is pretty obvious: If a bolt or component is wired into place, you have a pretty good idea that the fastener was tightened in the first place (believe it or not, there are plenty of cases where, in the heat of re-assembly, people forget to tighten stuff). The second reason is equally obvious: Safety wire is used so that a bolt or some other fastener doesn’t fall off. But there’s a catch here. The world’s best job of “safetying” a fastener won’t stop the fastener from loosening. That’s not the job of the safety wire. All a piece of safety wire will do is to limit the amount of rotation available to the fastener, which in turn prevents it from backing off any further. Keep this and the first reason in mind when you safety wire components together. Almost any form of wire can be used to safety parts together. In a pinch, some people have used everything from iron mechanic’s wire to copper wire to get the job done. But there is a better product, and it’s dedicated (for the job) 302 stainless steel safety wire. This product comes in rolls and is available in diameters of 0.020, 0.032 and 0.041-inch. The most widely used is the 0.032-inch diameter material (Mr. Gasket part number 8022G), and for the most part, it’s pretty much the choice for most race mechanics. There are many different ways to twist the wire, but the easiest is by way of safety wire pliers (shown in the accompanying photos). These tools aren’t exactly cheap, but if you safety-wire pieces on a regular basis, you’ll be glad you have a set. Very good examples are available from Mr. Gasket (part number 8023G). To work with the wire, first cut it to length. This is a case where too much is just about right. The worst thing that can happen is to find you’ve run out of wire length right before finishing the job. Simply stated, it’s a whole bunch easier to cut off excess wire than to start the job from scratch. Next, insert the wire through the hole in the fastener and loop it around, not over, the head of the fastener in the direction that tightens the bolt. Remember that some fasteners have left hand threads. The bottom line here is, remember to always install (and then twist) the wire in the direction that tightens the fastener. Otherwise, the safety wire can’t do its job. At this point, pull the wire tight. Figure out how much “twist” length is required for the job and begin twisting it with the safety wire pliers. Twisting alone will not properly tighten the wire. The twisting action is actually used to take up any slack in the wire. If you twist the wire too tightly, you run the risk of breaking the wire. On a similar note, pliers not designed for safetying have a bad habit of marking the surface of the wire. That too can cause the wire to break. Keep in mind that it might break when you least expect it. Generally speaking, the rule of thumb for twisting wire is eight to ten turns per inch. It’s a good idea to get the wire as tight as possible. To accomplish this, try to leave approximately 0.250-inch of untwisted wire before it passes through something like a second bolt head. This will allow you to pull the wire tight as you pass the loose end around the fastener head (in the direction of the fastener tightening). At this point, you can twist the wire while pulling on it. You might have to use a hefty tug to pull it tight. There may be a couple of situations in which you might want to leave the safety wire slightly loose. The reason for leaving the wire a bit on the loose side is that it allows you to visually check the safety wire quickly. If the wire has tightened up, you know that the nut is trying to back off. Once you’ve finished twisting and turning, cut off the excess length (often called the “pigtail” or “tab”). The idea is to leave approximately ½-inch of twisted wire sticking out on the backside of the last bolt or fastener. With a set of pliers, bend this material back onto itself, forming a loop (hence the term “pigtail”). What you want is a situation where the rounded portion of the loop is what comes in contact with your hands, clothing or whatever. A rounded pigtail is far less likely to puncture you or your clothing. When working with safety wire, a magnet is your friend. Reason is, cut-off wire from the pigtail ends has a nasty habit of ending up in places it shouldn’t be – and that can include tires. Those little chunks of wire are sharp!

Safety First: Safety Wire

Click Here to Begin Slideshow

In several past issues, we took a detailed look at aircraft fasteners. If you recall, several of the fasteners are designed to be safety wired. Aviation isn’t the only place you’ll find safety wired fasteners. Many road racers safety wire things like fasteners for ball joints, brake hardware and so on. These are important products, but we won’t go into what parts need to be safety-wired. Instead, what follows is the right way to use safety wire:

There are good reasons why safety wire is used on aircraft, race cars and race motorcycles. The first is pretty obvious: If a bolt or component is wired into place, you have a pretty good idea that the fastener was tightened in the first place (believe it or not, there are plenty of cases where, in the heat of re-assembly, people forget to tighten stuff).

The second reason is equally obvious: Safety wire is used so that a bolt or some other fastener doesn’t fall off. But there’s a catch here. The world’s best job of “safetying” a fastener won’t stop the fastener from loosening. That’s not the job of the safety wire. All a piece of safety wire will do is to limit the amount of rotation available to the fastener, which in turn prevents it from backing off any further. Keep this and the first reason in mind when you safety wire components together.

Almost any form of wire can be used to safety parts together. In a pinch, some people have used everything from iron mechanic’s wire to copper wire to get the job done. But there is a better product, and it’s dedicated (for the job) 302 stainless steel safety wire. This product comes in rolls and is available in diameters of 0.020, 0.032 and 0.041-inch. The most widely used is the 0.032-inch diameter material (Mr. Gasket part number 8022G), and for the most part, it’s pretty much the choice for most race mechanics.

There are many different ways to twist the wire, but the easiest is by way of safety wire pliers (shown in the accompanying photos). These tools aren’t exactly cheap, but if you safety-wire pieces on a regular basis, you’ll be glad you have a set. Very good examples are available from Mr. Gasket (part number 8023G).

To work with the wire, first cut it to length. This is a case where too much is just about right. The worst thing that can happen is to find you’ve run out of wire length right before finishing the job. Simply stated, it’s a whole bunch easier to cut off excess wire than to start the job from scratch.

Next, insert the wire through the hole in the fastener and loop it around, not over, the head of the fastener in the direction that tightens the bolt. Remember that some fasteners have left hand threads. The bottom line here is, remember to always install (and then twist) the wire in the direction that tightens the fastener. Otherwise, the safety wire can’t do its job. At this point, pull the wire tight. Figure out how much “twist” length is required for the job and begin twisting it with the safety wire pliers. Twisting alone will not properly tighten the wire. The twisting action is actually used to take up any slack in the wire. If you twist the wire too tightly, you run the risk of breaking the wire. On a similar note, pliers not designed for safetying have a bad habit of marking the surface of the wire. That too can cause the wire to break. Keep in mind that it might break when you least expect it. Generally speaking, the rule of thumb for twisting wire is eight to ten turns per inch.

It’s a good idea to get the wire as tight as possible. To accomplish this, try to leave approximately 0.250-inch of untwisted wire before it passes through something like a second bolt head. This will allow you to pull the wire tight as you pass the loose end around the fastener head (in the direction of the fastener tightening). At this point, you can twist the wire while pulling on it. You might have to use a hefty tug to pull it tight. There may be a couple of situations in which you might want to leave the safety wire slightly loose. The reason for leaving the wire a bit on the loose side is that it allows you to visually check the safety wire quickly. If the wire has tightened up, you know that the nut is trying to back off.

Once you’ve finished twisting and turning, cut off the excess length (often called the “pigtail” or “tab”). The idea is to leave approximately ½-inch of twisted wire sticking out on the backside of the last bolt or fastener. With a set of pliers, bend this material back onto itself, forming a loop (hence the term “pigtail”). What you want is a situation where the rounded portion of the loop is what comes in contact with your hands, clothing or whatever. A rounded pigtail is far less likely to puncture you or your clothing.

When working with safety wire, a magnet is your friend. Reason is, cut-off wire from the pigtail ends has a nasty habit of ending up in places it shouldn’t be – and that can include tires. Those little chunks of wire are sharp!

Safety First: Safety Wire 1

This is a set of safety wire pliers available from Mr. Gasket. This tool acts as a cutter and a wire twister as well as a heavy-duty pair of pliers. It’s possible to grip, twist and snip safety wire faster and more efficiently with this tool.

Safety First: Safety Wire 2

The first step in using the pliers is as follows: Once you’ve wrapped the safety wire through the fastener or around the object, grip both ends of the wire in the jaws of the safety wire pliers.

Safety First: Safety Wire 3

Slide the sleeve (the plated perforated piece in the center of the pliers) down with your thumb, toward your body, to lock the handles.

Safety First: Safety Wire 4

Grasp the knob located in the center of the pliers and gently pull out. This will cause the plier handles to turn, which obviously twists the safety wire.

Safety First: Safety Wire 5

After the appropriate twists are complete, squeeze the handles of the pliers. This releases the safety wire from the plier jaws.

Safety First: Safety Wire 6

Use the cutters in the jaws to snip the safety wire to the proper length; bend or loop the end of the wire over so that you don't stab yourself the next time you work near the wire.

Safety First: Safety Wire 7

Safety wire is available in two material types and three different diameters. You can buy either brass or stainless steel wire. Wire diameter is available in 0.020, 0.032 and 0.041-inch sizes in both brass and stainless.

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  • Jim Stricklin

    magnets don’t do a very good job on stainless wire.

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