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The roll pin opening on most coil plungers will have a chamfered (beveled) edge on one side of the opening. This helps "funnel" the roll pin into the opening as it's being installed, and eases installation.
If the plunger you're working with doesn't have a chamfered edge, you can make one by lightly drilling one side of the opening with a drill bit. A 9/64-inch bit works well for most common 1/8-inch roll pin openings.
Don't ever use pliers or vise jaws to hold a coil plunger by it's sides- this will damage the sides of the plunger and can cause premature wear/tear on the coil sleeve, or faulty operation.
We recommend laying the coil plunger on it's side in the groove of slightly-opened vise jaws, as shown here. Optionally, you can put a towel or cloth underneath the plunger to avoid scratches as you work.
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One good way to get a roll pin started into an opening is to use a pair of Vise Grips to squeeze one end of the roll pin so that it fits easier into the opening.
You'll want to adjust your Vise Grips so that they don't crush the roll pin, but give just enough squeeze to close the opening in the side of the roll pin, as shown in the first image at the left.
Click here to watch a short YouTube video on how this is done.
Once the roll pin is in the Vise Grips, you can push it a little way into the opening on the coil plunger to get it started.
Twisting the roll pin as you're pushing it can help make this step easier.
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Once you've got the roll pin started into the plunger, you'll want to tap or press it in a bit farther so it just starts to emerge from the other side of the plunger tip, as shown in the first image at the left.
This will help to position the linkage part that you will be connecting to the plunger via the roll pin. The linkage part can be set inside the plunger, just over the protruding roll pin (as long as you haven't pressed the roll pin in too far). This helps center it in the plunger so that the roll pin will go properly through the opening in the linkage as you continue to tap/press the roll pin in.
The roll pin can be tapped in with a hammer, or pressed in with vise jaws or a dedicated press.
Some plungers may allow a roll pin to be hammered or pressed-in without bending the ends of the plunger, but others may not be as structurally strong.
If you notice any bending of the plunger ends while you are hammering or pressing in the roll pin, or just want to be safe and avoid this possibility altogether, we recommend using a thick washer (or other type of "shim") set just inside the end of the plunger, to help hold the tips apart and prevent them from being bent inward, as shown in the second image at the left.
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Once you've got your linkage part set in the plunger, and it's hole centered over/on the protruding roll pin, you can continue to tap/press the roll pin in.
To further aid in preventing the tips of the plunger from bending inward during this process, you can add another washer/shim under your linkage part to help fill up the gap between the plunger tips, and prevent them from bending during further tapping/pressing, as shown in the second image at the left.
This may not be necessary on most plungers, but if you're concerned about bending or the plunger tips strength, we recommend doing this.
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Continue to tap/press the roll pin through until it is centered in the plunger, as shown at left.
Remove any shim(s) you may have used, and your part is ready to go.
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Roll Pin Installation
Roll Pin Installation
