Troubleshooting Your Servo Problems

The following questions relate to common problems that arise with your servo.

  • Q. My servo does not center properly.
    • A. There can be several reasons why a servo will not appear to center well, here are some common ones:
    • Wrong servo horn

      Hitec servo output shafts are unique and unlike any other brand of servos. Do not use any horn not specifically  
      designed for the Hitec spline or it may "skip" on the splines and cause a catastrophic failure.

    • Slop or binding in the linkage
      Try removing the control linkage from the servo and make sure the steering or control surface moves freely
      without binding or too much "slop".
    • Slop or wear in the geartrain
      Metal geartrains will wear at a greater rate than resin or plastic gear sets. Normal use will result in increased gear
      lash or "slop" over an extended period of time.
    • Sloppy servo saver
      Servo savers, like the Kimbrogh products and others that use a spring to absorb shock through the steering
      system of R/C cars, trucks and buggies can cause a "double center" condition that will drive you crazy as you
      chase the center with your radios steering trim.
  • Q. How do I check Servo Centering?
    • A. Remove the servo from the plane or vehicle. With the arm still attached to the servo, place an ink dot towards the end of the wheel and another one on the case, these should be lined up for a reference point. Plug the servo into the receiver and move the corresponding transmitter gimbal stick or wheel from stop to stop. After each movement, check the reference points for alignment.
  • Q. How do I fix the grinding noise or erratic behavior of my Servo?

    • A. Open the case and remove the gears. Examine them for broken teeth. If broken, replace with a new gear set.

  • Q. What do I do if my Servo jitters while idling at center or through its travel?

    • A. This may be a dirty potentiometer. Open the case and remove the gears. Spray a zero-residue tuner cleaner into and around the "pot" and work it in. Once the cleaner has dried, re-install the gears and close up the case.

  • Q. What do I do if my Servo is locked in place?
    • A. Open the case and make sure the gears are properly aligned. Next check the case top for wear, if wear is evident, replace the case.
  • Q. What do I do if my Servo hums under load?
    • A. This can be normal, the servo is trying to hold position against the force of a load. If it hums when no load is applied, try loosening the servo case screws a quarter turn.
  • Q. What do I do if my Servo gets hot?
    • A. Turn it off! Check the servo wiring, it should match the receiver being used. The motor could also be stalled due to a failed geartrain or a binding linkage. If non of these issues appear present, you may want to let our team of service professionals take a look at it.
  • Q. My servo gears broke, how do I change them?

    • A. Hitec offers gear sets for all our servos and these are available from your local hobby shop or from a mail order retailer.
    To replace the gears on any servo, carefully lay out the new gears on a clean work surface to have them available for re-assembly. You will also need a supply of servo gear lubricant, we suggest the Hitec lube part # 58450. Loosen or remove the screws located on the bottom of the servo case enough to pop the upper case off and expose the gears. If any gears or shafts are stuck in the upper case, remove them and plug them back into position on the lower case.
    Now carefully remove the gears while placing them in approximate order on your work surface in front of you. This is done so you can refer back to their positioning as you assemble the new set into the lower servo case. Clean all the old lubricant from the servo case in both the lower and upper case components. Be aware of small chunks of gear material that may be lodged in the lubricant and get it all cleaned out. Apply servo gear lube to the shafts and assemble the geartrain applying lube to all gear components. When complete, pop the case top back on and tighten up the case screws.
    CAUTION: Do not force the case top back on. If it will not fit back on smoothly, chances are the gears were installed incorrectly.

  • Q. What is servo grease?
    • A. Use only silicon based servo grease when replacing servo gears. Using other type of grease not intended for servo gears may produce a gas when used in sealed cases which may coat a nasty film on the motor brush that could stop the servos operation. Hitec recommends our product #58450, servo grease.

    Servos