Tuesday, November 5, 2013
CVT Transmission Disadvantages
First used in the U.S. market in 1989, Subaru Justy, the continuously variable transmission (CVT) is a different type of transmission which, instead of using a number of differently sized gears, uses a belt connected to a pair of variable or cone-shaped pulleys. It changes the size of the pulleys to simulate gears, but, instead of having only five or six choices, it can move in a nearly infinite number of steps, since the changes can be done quite smoothly. The idea behind this is that it can always keep the engine in its optimal power band for the best performance or fuel efficiency.
Limited Power Handling
The original CVT transmissions could only handle engines of 1.2 liters or less because the belts that they used would snap under the load of a more powerful engine. Although modern CVTs have stronger metallic belts or chains, they still cannot be used with engines that generate a great deal of torque, or pulling power.
Special Transmission Fluid
To protect their relatively delicate belts, many CVTs require a special transmission fluid which is extremely expensive to replace. It also can require more frequent replacement than the fluid in traditional automatic transmissions.
Unnatural Driving Feel
CVTs constantly change their drive ratio, acting as the equivalent of an automatic transmission with thousands or millions of gears. Because the transmission changes are so smooth, they lack the shift feel that accompanies the process of shifting through the four to six gears on most automatic transmissions. Because of this, many drivers believe that they feel unnatural.
Limited Fuel Economy Benefits
CVTs, theoretically, should deliver significant fuel economy benefits since they can always keep the cars engine at its optimal operating speed for providing the most power with the least fuel. However, many modern engines have a broad range of speeds at which they operate efficiently, allowing even a traditional automatic transmission to keep them within an optimized power band.
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