I found a neat product marketed by ServoCity. It is a Servo Stretcher. This electronic device increases the throw of a servo to almost 180 degrees. I tested this on My Robbe F14 radio using a Futaba micro servo. First the servo hooked was hooked straight to the receiver and powered up. Rotation was approximately 90 degrees, about right. Next I inserted the Servo Stretcher into the circuit between the receiver and the servo.
There are three adjustment screws on one end od the Stretcher and with those adjusted the servo gave me approximately 160-170 degree rotation.
Now the unit, it is composed of a heat shrink wrapped circuit board 2 1/4 inches long by 7/8 inch wide, and 1/2 inch thick. From one end extend two pigtails, one to the receiver and one to the servo. On the oher end of the board are found three adjustment pots. The center pot adjusts the centering position of the servo, and the outer pots adjust the range of rotation, right and left.
For $19.95, this is a neat device that increases the throw of your servo, adjusts the end points and the center resting position.It can be seen at