Tech Center: Servo Gear Blowout

I keep breaking the gears in my steering servo. It doesn’t happen every time I go out, but it’s been enough that I have had to replace the stock gears a few times already. Would buying a servo with metal gears solve the problem?

Although upgrading to a metal-geared servo adds durability, it doesn’t ultimately address why you are stripping the gears to begin with. Before you spend money on a new servo, take the time to look at your vehicle’s “servo saver.” The servo saver is designed to “give” when the steering system takes a blow or its travel is restricted by an obstacle, so strain that might otherwise damage the servo’s gears is absorbed by the servo saver instead. Depending on your model, the servo saver may be mounted on the servo itself, or incorporated into the steering system. In your case, chances are good that your servo saver is part of the steering bellcrank and has locked up (or has been overtightened) and is not doing the job that it was intended to do. If you can see that the servo-saver spring is fully compressed, loosen the adjusting collar to allow the servo saver to operate normally. Power up your car, and try to steer the front wheels with your hands while the servo holds neutral. The servo saver should absorb the steering movement. If it doesn’t, disassemble the servo saver and clean or replace its parts to restore smooth action.

Here’s a typical bellcrank-mounted servo saver. The collar (A) adjusts tension on the spring (B) to set how much force is required to activate the servo saver.

On some models, the servo saver mounts directly to the servo (as on this Traxxas Stampede). If this type of servo saver fails, it will usually disconnect the servo from the steering system, rather than locking up.