Continuously Variable Transmission (CVT) Problems

A car engine is an integral car part that provides the energy needed for driving the vehicle. The engine output refers to the torque or the twisting force which is produced as a result of the combustion of the fuel in the internal combustion engine. The rotational speed of a car engine is very high and it is essential to alter the speed ratio between the car's engine and its wheels. It is the car transmission system that helps in facilitating torque adaptation which allows one to drive the car at variable speeds. A continuously variable transmission (CVT) is a type of automatic car transmission system that has been incorporated in cars manufactured by established automakers such as Audi, Nissan, Ford and Honda. Unlike an automatic transmission which has a set number of gear ratios, cars with CVT use a pulley and belt system to provide an unlimited range of gear ratios. Though improved gas mileage and fuel efficiency are some of the strong points of this transmission system, car owners have encountered certain problems. Here's some information on how a CVT works and what are the most common continuously variable transmission (CVT) problems.

How Does a Continuously Variable Transmission Work

How does the CVT system differ from the traditional car transmission system? First of all, the gear set provides only a set number of gear ratios in vehicles that are equipped with a conventional transmission system. When you are driving a vehicle with a manual transmission, you would have to operate the clutch and shift gears to get the ratio required for driving the vehicle in a particular situation. While you use the lowest gear for starting up, you need to shift to higher gear for fuel-efficient driving. The gears basically help to use the torque effectively and keep the car's engine running at the right speed. In a car with automatic transmission, the speed and the engine load is measured by the computerized system and the needed gear shifts are automatically made as and when the system delivers an electronic signal.

Cars with a continuously variable transmission system make use of pulleys and belts to provide varied gear ratios. This system consists of a pair of variable-diameter pulleys. While the input pulley is the one connected to the engine, the output pulley is connected to the drive wheels. A metal belt runs between the two pulleys. When the pulley halves come closer to each other, the metal belt or chain goes higher on the pulley thereby increasing the diameter of the pulley. It is the change in the diameter of the pulley that brings about the varied transmission ratios. A low ratio would be achieved when the diameter of the input pulley is smaller than the output pulley. Thus, the change in the diameter of pulleys plays a great role in changing the ratio of engine speed to car speed. Unlike the traditional transmission where the ratio changes in stages when you shift gears, the ratio changes continuously when one drives a car with a CVT system.

While pulley-based system is commonly used by automobile companies, you will also find cars that are equipped with hydrostatic or toroidal CVT systems. In case of a toroidal CVT system, the objective of getting varied gear ratios is achieved by using power rollers and discs. On the other hand, hydrostatic CVT mechanism involves the use hydrostatic pumps and motors for the same purpose. Unlike the automatic transmission where you feel a change in the engine speed while shifting gears, people who drive cars with CVT system don't feel such gear shifts.

Problems Associated with Continuously Variable Transmission

The CVT mechanism has its advantages and disadvantages. While improved acceleration and enhanced fuel economy are believed to be its strong points, some people have voiced their concern regarding CVT reliability. The fact that the CVT system is more expensive may affect the user acceptance in an adverse manner. Though car owners who drive cars with automatic transmission would also have faced certain problems, they might still find it difficult to adjust if they switch to a car with a CVT system. Cars with CVT do produce some noise when you try to accelerate. The car noise is produced as a result of CVT trying to adjust the engine speed. Though CVT mechanism allows the engine to rev at any speed, those who have driven such cars would have to get used to hearing sounds that seem like noise made by a slipping clutch. Those who are accustomed to driving cars with automatic transmission might find that slightly bothersome.

While a CVT system is supposed to provide a smooth transition while accessing maximum power, there have been complaints about jerky movement during initial acceleration or rattling during slow speeds. Problems could even be caused due to the use of incorrect transmission fluid. Using the wrong fluid can prove to be problematic in the long run, so check if you are using the appropriate fluid. Failure of the electrical sensors or the computer that controls the transmission can also cause malfunctioning of the transmission. CVT reviews have been somewhat mixed which is why automakers are trying to incorporate improved CVT parts to solve transmission problems. Established automakers such as Toyota, Ford and Lexus have incorporated electronic CVT in their hybrid vehicles. An electric motor-generator is used to continuously alter the ratio of the wheel speed to engine speed. Long-term reliability is still an aspect that needs to be looked into. Since CVT system is very different from conventional transmission, prospective buyers should prepare themselves to adjust to the dynamics. So go for a test drive to check whether you are comfortable driving a car with CVT.

While automobile enthusiasts may be tempted to go for cars with a CVT system due to the superior fuel economy and better acceleration it offers, they should go for a test drive and buy a CVT-equipped vehicle only if they get a smooth driving experience.