Definition of Transmission...
The gearbox that multiplies engine torque via gear reduction and/or torque conversion. A typical manual transmission has four or five speeds, with the final or highest gear being either a direct 1:1 drive ratio or an "overdrive" ratio (less than 1:1).
An automatic transmission first multiplies engine torque as it passes through the fluid coupling known as the "torque converter" (appropriate name, huh?) and then through three or four separate gear ratios. A manual transmission usually gives slightly better fuel economy than an automatic because there is a certain amount of slippage that occurs in the automatic's torque converter. A manual transmission is normally trouble-free-except for the clutch, which can be very troublesome if adjusted incorrectly or abused. With automatics, the leading problem is fluid breakdown from overheating. Fluid and filter changes every 24,000 miles can avoid premature transmission failure but few people heed such advice. Consequently, automatics often call it quits long before they realize their potential design life.
