Servo Savers/Servo Horns

How to Differentiate and Choose Between Inserts

The servo saver/servo horn insert is a source of confusion for many. I often hear the suggestion to, "just use the insert that fits tight". In reality they all can fit fairly tight, so that's not really an accurate way to determine the correct insert. Using the wrong insert will cause you problem after problem with whatever that servo is controlling. For instance, with the steering servo, you might notice the wheels never straighten back up after a turn or a jump. You may even notice that your truck never turns at all. These are symptoms of using the wrong insert in the servo saver.

It's important to know that while all servos are not the same when it comes to the output shaft that the servo saver, or servo horn, fits on. These different types of output shafts can be classified into three categories: Airtronics, Hitec, and Futaba. Each of these have a different number of splines on the output shaft. Splines are the ridges that are similar to the teeth on a gear. You may notice that the brand of servo you use might not be one of these three categories. However the servo output shaft will be the same as one of the ones mentioned.

When you use a servo saver, or servo horn, that requires inserts it will usually include several of them. These inserts will be marked, but it's often not very obvious. For example, look at the picture below. These inserts are from a stock Traxxas servo saver. The identifying number is molded onto the insert. In this picture for clarity purposes, I have taken a permanent marker and marked the number so it shows up in the picture. If you were looking for the number yourself it would be white and blend into the insert.

Other servo savers, or servo horns, may have a different method to mark the inserts. For instance Kimbrough uses the letters A, H, and F. These letters are also found on the plastic tree that you pull the insert off of. So if you separate the inserts from the tree without marking them, the only way you can tell the difference is to count the splines inside the insert. If this becomes necessary, mark one of the splines with a fine point marker as a starting point and then count each one until you arrive back at the starting point. This method can come in handy for any servo saver insert that is not marked.

Now that you know how to tell the difference between inserts, you probably want to know how they relate to the markings or spline count.

Kimbrough Servo Savers

Traxxas Servo Savers