Manual Transmission

Manual transmissions and transaxles have become more popular today than in past years for a few reasons. One obvious reason is the increased fuel economy that a manual transmission is capable of. Then there are a growing number of drivers that prefer a manual transmission where they can shift the gears when they decide it is efficent to do so.

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 and the countershaft is often referred to as the cluster gear and the output shaft can be called the main shaft.

Synchronise 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 cone 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 fairly 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 synchronisation 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 catastrophic failure as well.

The transmission/rear 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.

At National Transmission we are the experts in all transmission and drive train repairs. We take complicated processes as shown above and with experienced technicians get your car or truck back on the road again.