Ford Repair: 93 ford explorer starting system problems, check voltage, harmonic balance

Question
with out any previous problems my explorer would only click when ignition switch was activated. i tried to jump start the car with two different cars and same click from the starter relay. i replaced the relay and have the same click from the relay. i then replced the stater solenoid on the top of the starter. again the same click fron the relay. i then checked the battery and have 12.4 volts when i energise the ignition it drops to 11.5 volts. i then had someone turn the ignition on and i got under the car and measured the voltage at the starter main lug it measures 11.3 volts. also i turned the engine over by hand with a socket on the harmonic balance. it turns fine not seized. helpppppp

Answer
Ok here are some things I want you to check. You mentioned checking voltage at the starter at 11.5 volts with key on, is that at the large starter terminal, and the key in crank positon? And also check the small terminal on the solenoid for power when key is turned to crank position. Make sure all the connections are clean and tight. A dirty or loose connection at the battery will allow the relay to click, but may not allow enough amperage to turn the starter. If you have voltage at both terminals on the solenoid, check voltage at the starter terminal while someone turns the key to crank position. If you have voltage there then the starter is bad.