--Part 2: a closer look at the gears -    • How an Evinrude gearbox works part 2 ...  

-update: I recently replaced the control cables on both of my motors, thus having to tune them. I noticed that if you have a very tough, or loud sounding connection when changing gears, this may be due to overly high rpm at idle. To fix this turn the control cable adjustment so that at idle, when switching forward / reverse its smoother. You do not want the motor switching at too high speed as it can the damage gears. You will need to find the exact balance, if idle is too slow the engine may die when shifting into gear.

This gearbox is from a 1967 Johnson 33HP Seahorse motor. That may seem old, however this part of the engine has pretty much not changed since; at least in medium to small HP motors.

General information on how outboard motor gearboxes work

--The lower unit houses the gearcase / gearbox / transmission / propeller on most engines.