Conditions when the car trouble occurs.
Noise is heard when shifting into one particular gear, the noise do not occur on other gears when shifting.
Possible reasons of car trouble
1. The teeth of the involve gear is damage
2. The bearings of the involve gear is damage
Troubleshooting noise problem when moving in one particular gear
When there is noise problem that occurs when shifting in one particular gear it means that there is a problem on the gear specifically the involve gear when shifting. This kind of problem is commonly cause by a problem of damage gear teeth of the involve gear or a problem of damage bearings for that particular gear.
One way to determine which of the possible causes is the culprit drive the car on uphill road or on an inclined road using the affected gear. Observe on what road condition is the noise getting worse. If the noise on the affected gear is getting worse when driving the car uphill or in an inclined road as the level of noise when driving the car on level road at same gear then the problem is the damage bearings of that particular gear. However if the noise is the same when driving on uphill or inclined road as compare with the noise while driving on a level road then the problem is the damage gear teeth of the affected gear.
How to correct the problem of transmission noise when moving in one particular gear
Problems that involves a transmission is very difficult to determine unless the transmission is opened up and inspected by a professional, in this case the above reason is only a possible cause of the problem you need to bring the car to a shop that specialized in transmission repair and ask the mechanic to inspect the transmission according to the above possible cause that stated above.