Servo Savers/Servo Horns

What Are They, and Do I Need One???

A servo saver is a device, with a inner spring, that connects your steering rods to the servo output shaft. Most of the time a servo saver is made of plastic, and is installed directly on the servo itself. However in some applications it will be built into a car or truck, and look more like a shaft with a spring on it. It absorbs driveline shock during normal driving and also provides protection in the event of a crash.

The job of a servo saver is to protect the servo and so, in the event of a bad collision, it will provide stress relief if the need arises. In some cases, stress relief is the servo saver breaking, but it's much cheaper to replace a servo saver than a servo. Below are two examples of a servo saver. The first one is a standard plastic servo saver, while the second is from Schumacher Nitro Menance. It resembles the servo savers that can often be found on some off-road trucks and many touring cars.

A metal gear servo is a good upgrade. However often people think that when they make this upgrade, the servo saver isn't necessary anymore due to the increased strength of the metal gear servo. This couldn't be further from the truth. First of all, metal gear servos are quite a bit more expensive than their plastic brethren, and nowhere is a metal gear servo deemed indestructible. This is due to the fact that even the best metal gear servos still have a potential weak point in them, it's commonly referred to as the "first gear". Let's examine the insides of a Hitec servo, which is one of the most commonly recommended replacement metal gear servos.

Notice what Hitec calls the "MP gear". This is the first gear I referred to. Hitec has developed a way to surround a metal gear with plastic to make a stronger first gear. It does increase the strength of the first gear when compared to other metal gear servos that run a solid plastic first gear, however it can still fail. In any metal gear servo the first gear would not be very likely to break as it would have the least amount of force acting against it. With Hitec's setup it is even less likely due to the fact that the internal set of teeth are metal. This gives the servo only one place to fail, the outside teeth of the first gear. However, failure is still possible.

As I mentioned before, all metal gear servos will have some form of weaker or "different" first gear, even if they claim "all metal gears" as Hitec does with some of their servos. While in some cases all metal gears may be true, I find this very somewhat misleading, and I'm sure many people have bought into this marketing approach. The first gear must be fashioned in a way to prevent radio interference. If all of the gears were exactly the same, severe radio glitching could be a problem. At that point how strong the servo was would mean absolutely nothing, as it would be next to impossible to drive.

This brings me back around full circle to the original topic, should you run a servo saver? The answer is yes, and it should be used even with a metal gear servo. The servo saver will help protect the metal gear servo from failure just as it would a plastic gear servo. So even though a metal gear servo is quite a bit beefier than a plastic servo, and overall will accept much more abuse, it is not indestructible. So it should still be offered some protection from serious shocks.

What Are Servo Horns, And Can I Use Them Instead?

Servo horns are often made of plastic, but their similarity with servo savers ends there. They are usually a single part, and do not offer any protection to the servo. Since they offer no protection, they should not normally be used with a steering servo. However some trucks, such as the Traxxas Revo, employ servo horns in addition to a servo saver for steering. This does provide adaquate protection as the horn is used in conjunction with a servo saver. The most common place to see an example of a servo horn is on the throttle servo on a nitro-powered vehicle. Below is an example of a servo horn on a T-Maxx's throttle servo.