Automakers have always been in pursuit of creating the best vehicles possible, whether it be in the field of engine power or aesthetics.
And from the many innovations engineers were able to come up with over the years, the continuously variable transmission remains to be one of the most efficient inventions to date.
Unlike manual and automatic transmissions, continuously variable transmissions work a bit differently, and some drivers might even argue that the feel of driving a vehicle with this type of transmission is different as well.
A Thing or Two About CVTs
A continuously variable transmission (CVT) is a type of setup found in many front-wheel-drive (FWD) vehicles that use a transaxle.
Unlike hybrid vehicles that use two electric motors, the Internal Combustion Engine, and a single planetary gearset as a CVT, a standard CVT uses two variable width pulleys or variators to change the gear ratio instead of using three or four gears.
Why Use a CVT?
Using a continuously variable transmission offers a lot of benefits. First, this type of transmission lets the engine operate in a speed range where it is most efficient.
A CVT helps the engine maintain a constant speed as the pulleys change to increase vehicle speed, resulting in improved fuel economy and reduced exhaust emissions.
That being said, the pulleys are electronically controlled to provide different gear ranges rather than working like a go-cart, which uses centrifugal force on one pulley and spring force on the other.
CVT Operation
In a continuously variable transmission, the two variators move at the same time.
The variators have different diameters with one being smaller than the other. The difference in diameter is necessary to let the drive chain move and change the ratio between the input and output pulleys.
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Pro Tip: CVTs with a chain type belt may seem peculiar, because the metal CVT belt that travels around the pulleys actually pushes rather than pulling, as you’d expect from a belt.
Using variable width pulleys and a special chain, a CVT can provide an infinite number of speed ratios.
A CV transmission has a total of four parallel shafts. These include:
- Input shaft
- Drive pulley shaft
- Driven pulley shaft
- Secondary gear shaft
The secondary driven gear and final drive gear make up the secondary gear shaft. The final drive gear is meshed with the final driven gear in a conventional open differential assembly.
When the transmission is placed in park, the parking prowl interlocks with the park gear, holding the secondary drive gear stationary.
Known Problems With Popular CVT Transmissions
A wide range of makes and models are offered with a continuously variable transmission nowadays, with some being more popular than others.
Nissan, Honda, and Toyota are some of the most popular brands offering CVTs across their models, but that doesn’t mean these vehicles come without issues.
Check out some of the most common CVT problems found in various models from these automakers.
Nissan CVT Transmission Problems
Shuddering Transmission
The infamous “judder” is arguably the most notable issue most Nissan CVTs have.
The “judder” occurs when the belt and pulleys begin to wear. Over time, the belt can slip and produce a shaking or shuddering sensation throughout the vehicle.
To resolve this issue, Nissan issued a software update that reprogrammed the transmission control module (TCM) to recognize the judder and log two possible diagnostic trouble codes:
- P17F0: CVT assembly replacement
- P17F1: CVT belt inspection
Abnormal Noises
Grinding and whining noises might be heard from certain Nissan models with a CVT due to worn-out bearings or gears in the transmission. In most cases, such noises could be heard upon acceleration and deceleration.
Overheating Transmission
A lot of Nissan owners with a CVT have reported about an overheating transmission that triggered their vehicles to go into limp mode.
This problem occurs because the belt and pulley inside the transmission generate more heat than the engineers anticipated, and it’s simply too much for the cooling system to handle.
Nissan has issued a technical service bulletin to address the issue, which involves installing an external transmission cooler in the affected units.
In some cases, however, the entire CVT assembly is subject to replacement.
Honda CVT Transmission Problems
Jerking Transmission
Many Honda owners with a CVT have complained about their vehicles jerking during initial acceleration.
Transmissions, in general, can jerk when gears begin to slip. For a CVT, the problem could be traced to a slipping belt.
Fluid Leaks
Leaking transmission fluid is never a good sign for any type of transmission, including a CVT.
Generally, transmission fluid leaks occur when the torque converter seal and fluid lines get damaged. The drain plug could also be leaking or the transmission fluid has been contaminated.
Hesitating Transmission
Some Honda owners have complained about their vehicles hesitating when shifting to drive or reverse, which could be attributed to low transmission fluid levels, a loose belt, or a malfunctioning clutch pack, among others.
Acceleration Issues
Hearing a loud acceleration noise is a normal thing for Honda CVTs, but a lot of drivers couldn’t seem to get used to it. This issue is typically caused by the engine running continuously at a high RPM.
Also, similar to some Nissan CVTs, certain Honda models have also been reported to lose acceleration and go into limp mode.
Toyota CVT Transmission Problems
Overheating
The constant change in gear ratios can cause most CVTs to overheat, including some models from Toyota.
A burning smell and an illuminated check engine light are common symptoms of an overheating transmission. Some of the reasons why this could happen include low transmission fluid levels, a faulty cooling system, and a damaged oil pump.
Clutch Issues
Problems with the CVT clutch can result in a jumpy start, rolling motion, and delayed engagement. A common solution is reprogramming the CVT clutch after changing the transmission fluid.
Slipping Gears
A slight jerking motion is normal for CVTs at low speeds, but a slipping or excessively jerking transmission usually calls for a trip to the nearest auto repair shop.
Low transmission fluid levels can disrupt the operation of the belt and pulleys, causing the transmission to jump.
Delayed Motion
Failing to replace contaminated transmission fluid or using the wrong variant can create a delayed response from the transmission.
Fluid leaks are also another thing to look out for, as they can cause similar or even worse problems for your vehicle.
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I own a Mitsubishi with a CVT, and have had no problems with it. Does Mitsubishi use the same CVT as Nissan?