During shifting into a reverse gear a grinding sound is heard coming from the transmission.

Transmission Troubleshooting
When shifting into gear the transmission is disconnected from the engine upon stepping on the clutch pedal. The same with shifting into reverse gear. Now, during shifting if the clutch is not fully release when the clutch pedal is depress the gears inside the transmission will clash this clashing of gears produce grinding sound. However, not all grinding sound that is heard during shifting is because of nit fully depress clutch pedal, there may be other cause of grinding sound that because of the complexity of transmission it can only be determined through a thorough inspection by a qualified professionals.