Are CVT Transmissions Really That Bad?
Continuously variable transmissions, or CVTs, have been increasing in popularity among manufacturers over the last few decades. Promising improved efficiency and a seamless driving experience, CVTs differ considerably from a traditional gearbox in many ways. In this article, we’ll go over what a continuously variable transmission is, how they operate, and what pros and cons these unique transmissions bring to the table.
What is a CVT?
CVTs forgo the traditional gears of transmissions in favor of a variable belt and pulleys, allowing them to dynamically change the transmission’s gear ratio rather than relying on the hard-set gear ratios of traditional gearboxes.
By allowing for seamless shifts, CVTs are able to change to the optimal gear ratio on the fly. This keeps the vehicle running as efficiently as possible no matter the current speed of the engine and prevents the delay in power delivery caused by the engine disengagement needed for traditional gear shifting.
How Do CVTs Work?
While most transmissions make use of various gears set to specific gear ratios, switching through them as needed, CVTs instead use a relatively simple set of conical pulleys to alter the ratio of the variable belt (v-belt). Though CVTs don’t technically have “gears”, we’ll still be referring to them as high and low gear ratios for the sake of simplicity.
One of these pulleys connects to the engine’s output (driving pulley) while the other transfers power to the vehicle’s wheels (driven pulley). By pushing and pulling these cones apart, CVTs alter the radii of each pulley which in turn changes the gear ratio of the entire assembly.
When one pulley pushes the cones together to increase its radius, the pulley on the opposite side will pull apart and reduce its radius, pulling the belt taut. For example, increasing the radius of the driving pulley and decreasing that of the driven pulley will result in a “higher gear” due to the increased rotational speed of the driven pulley.
With the ability to change each pulley to its desired radius, CVTs effectively have an infinite number of possible gear ratios.
Benefits of a CVT
There are a few reasons that CVTs have become so popular among manufacturers in recent years.
For one, the virtually infinite and variable gear ratio allows the vehicle to run at peak efficiency at any speed, providing optimal MPG that may be lost with a traditional transmission.
The less complex design of CVTs also means that they tend to be easier and cheaper to produce, and some of those cost-savings may be passed onto you, the customer, when purchasing a CVT-powered vehicle.
With fewer components also comes less weight. CVTs are generally significantly lighter than traditional transmissions, bringing both increased performance and efficiency as the vehicle has less mass to move.
Common CVT Issues
Overheating
While the use of belts and pulleys in place of gears brings various benefits, it also introduces a large amount of heat due to the friction of the rotating pulleys and v-belt.
Typically, this heat should be mitigated by the cooling system, however, there have been many reported cases of CVTs overheating despite a healthy cooling system.
Overheating can also be caused by a lack of adequate transmission fluid, which can leave your CVT without proper lubrication to prevent heat buildup.
Transmission Shudder
Also a byproduct of the pulleys and belt, CVTs can develop an odd shuddering or shaking feeling over time. This occurs when the pulleys and belt have worn down, either allowing the pulleys to loosen and shift position or for the v-belt to slip off the intended track. Nissan CVTs have been especially problematic in this regard.
Not only does this issue cause a concerning shudder and unusual noises, but it also means the internals of your CVT are experiencing mechanical issues that could worsen and cause irreparable damage if left untreated.
Whining/Grinding Noises
Similar to transmission shudder, CVTs may start producing worrying grinding or whining noises. This generally occurs for similar reasons to the shuddering condition, such as a loose pulley or other mechanical failures such as worn-out bearings.
Any new noise from your transmission should always be treated with urgency, as continuing to drive could cause these issues to only get worse. In some cases, this could even lead to complete transmission failure.
Jerking Acceleration
When CVTs are low on fluid, they may cause the vehicle to jerk forward during acceleration as the transmission fights against friction.
It should be noted that slight hesitation can be normal at low speeds with a CVT, but an excessively jerking transmission is likely a sign of a larger issue.
Keeping your CVT running with an adequate amount of the correct transmission fluid is vital to maintaining your transmission and preventing mechanical issues like these from affecting your drive or damaging your drivetrain.
Are CVTs Reliable?
With over three decades since their introduction to consumer automobiles, CVTs have had their fair share of time to iron out many of the larger issues. Modern CVTs have solved many of the issues that plagued early CVT models, and in general, new CVT vehicles are very reliable.
This isn’t to say that CVTs won’t experience issues, however. Maintaining and servicing your CVT is crucial to preventing symptoms like these from developing.
Transmission Services at Beachlers Tire & Automotive Center
No matter if your vehicle has a CVT, DCT, or just a regular gearbox, the experienced technicians at Beachlers Tire & Automotive Center in Peoria have the training and equipment to properly service your vehicle’s transmission! Give us a call or schedule online today to speak with our friendly and knowledgeable team.