The transmission is a group of parts that transmits power from a vehicle’s engine to the drive axle, which
in turn makes the wheel go around. If you do not use a clutch to switch gears, your vehicle has an
automatic transmission. If you use a clutch, your transmission is manual. Automatic Transmissions
contain an oil-like fluid to cool and lubricate the mechanism. The level and quality of this fluid should be
checked regularly (see your vehicle owner’s manual) and replaced if needed. If your transmission
performance seems good, the fluid is clear and red, and if you have not had to add fluid, leave your
transmission alone.

Manual Transmission and transaxles have become even more popular today than in the past, for a few
reasons. For one thing, a manual transmission is capable of increased fuel economy. Moreover, many
drivers simply prefer a manual transmission where they can shift the gears.

Manual transmissions work by use of a clutch that connects the engine flywheel to the transmission input
shaft. The input shaft spins on one end of the output shaft and they share the same axis, but are not
connected. The input shaft spins the countershaft which is below or beside the input and output shafts.

The gearshift lever moves the shifter collars, which lock various gears to the output shaft, and then the
input shaft turns the countershaft, which turns the output shaft. The input shaft is also called the input
pinion gear, the countershaft is often referred to as the cluster gear, and the output shaft can be called
the main shaft.

Synchronize rings are most generally brass rings located inside the shifter collars. As the shifter moves
the collar towards the gear, the brass ring in the collar rubs against a steel cone and slips into the one,
which it is being pressed against. This speeds the gear up or slows it down so the collar speed matches
the speed of the gear, which causes the gear lock in smoothly. You can hear the gear spin up by
downshifting at a high speed with the clutch pressed in and then you will hear a distinctive “whirring”
sound.

As long as you keep oil in a manual transmission, it should last a very long time. It is generally only
when seals fail and leak out the transmission oil that a transmission will start to fail. High mileage
transmissions eventually use up the lifespan of either the bearings or the synchronizers. Bad bearings
make a noticeable rumbling sound and bad synchronization rings will make a grinding noise going into
gear or sometimes will even “pop out” of gear while under pull. Of course, severe misuse of a
transmission will result in failure as well.

The transmission axle or transaxle (front wheel drive) input and output seals have a spinning shaft going
through them with a liquid or lubricant on the other side of them. By design they will leak a very small
amount of liquid thus it is normal for there to be a little oil around the crank seal after a few years of
driving.