Shoulder Bolts 101: Getting To Know These Unique Fasteners

Fastening bolts can be designed very differently from one another depending on their intended purpose, and shoulder bolts are one of the more unique types. Here is a look at just a few of the things you should know about these interesting bolts, their design, and their purposes.

What exactly are shoulder bolts?

Shoulder bolts are fasteners that have a threaded end and unthreaded stem between the end of the bolt and the head of the bolt. If you are looking at one of these bolts, you will see a ridged, threaded tip, a smooth center, and a bolt head at the top. While the basic formation is pretty much always the same, there can be variances in how much of the bolt is threaded, how much is smooth, and of course the diameter of the bolt. 

How should shoulder bolts be used?

Shoulder bolts have the unique design to allow another component to rotate around the bolt itself even though the bolt is secured in place. Therefore, these bolts are really good for applications that require a piece to retain the ability to move for adjustment or function. You may find shoulder bolts fastened to things like: 

  • Cam rollers
  • Pivoting joints 
  • Levers 
  • Links 
  • Doors 

Are titanium shoulder bolts better than alloy steel?

You can find shoulder bolts created out of everything from alloy steel and titanium to stainless steel and nylon, and all of these bolts have value for different applications. While titanium is known to be more durable than alloy steel, these bolts are more expensive. And, they do not always provide a good return on investment unless you have a specific application that calls for such a durable bolt frame. For example, a shoulder bolt made out of titanium would probably be best for use in an automotive flywheel, but it would be a bit overkill for use on a door hinge. 

What does it mean if a shoulder bolt has a nylon patch?

You will see these bolts advertised with various types of patches, and these implements do serve a valuable purpose. For instance, the shoulder-style bolt with a nylon patch is designed specifically to provide you with prevailing torque. In layman's terms, this means the bolt threads will lock into place all on their own without the addition of another additive to create a tight bond in a threaded hole once the bolt is inserted.