The benefits of CVT have been repeated many and many times over – simple design, better fuel efficiency, smooth gear shifts, and infinite gear ratios. So much so, that city cars by Nissan, Honda, and Toyota mainly use CVTs.
Common fears regarding CVT are overheating CVTs and snapped CVT belts. But how much truth is there to these fears?
CVT overheating is real. It damages the CVT fluid and consequently everything else. Overheating could also break the CVT belt.
There are two causes of overheating CVTs
car is designed for colder climate (usually recond cars)
lack of care/knowledge of car owner
Recond cars in Malaysia usually face this issue since they were originally designed for colder climates. The problem can be easily fixed by installing an oversized aftermarket CVT oil cooler.
Another cause of overheating is the lack of maintenance. When not serviced for extended periods, the fluid becomes less effective in dispersing heat. There have even been cases of owners putting regular ATF inside a CVT. This is pretty much a death sentence to your CVT, since it has its own grade of fluid.
CVT belts can snap and there is usually no warning beforehand. The CVT belt connects the driver pulley and driven pulley in the gearbox. When the belt snaps, the engine is unable to drive the wheels.
A CVT belt is made of elements and ring packs. More ring packs make the belt stronger.
The belt is made of a few hundred components so you can imagine the mess in the gearbox when it snaps. Your need to get the car towed and a typical solution is a total gearbox replacement - very expensive.
The main cause of snapped belts is aggressive driving or too much power. CVTs are not exactly heavy duty. That’s why they are equipped on city cars and not high-performance cars.
You’re not supposed to "launch" CVTs, neither should you tune the engine beyond the CVT's limit.
So, there you go. The reliability issues of CVTs are very much avoidable. Only some makes have terrible CVTs and we'll get to that later.
Q: Why are CVTs becoming more common?
A: CVTs are becoming more common since they have less moving parts, are generally smaller, cost less to make, and are more fuel efficient. Plus, the average driver couldn't be bothered about "driving engagement".
Many reliable Japanese makes have chosen to fit their cars with CVTs, and the technology has become more reliable over the years. There is no denying its benefit of simple design, better fuel efficiency, and smooth drive.
Q: If CVT is so good, why did Proton revert to the conventional 4AT?
Proton's Punch-sourced CVT utilises a start-up clutch instead of a torque converter. That is one of the reasons why the ride was not as smooth as other CVTs. Hence, the swap to conventional 4AT with a torque converter made sense.
The "wet-clutch CVT" required drivers to adapt to the CVT's unique behaviour. Apparently, many found that to be a hassle. Driving an automatic should be easy, right?
The design of the conventional 4AT itself is also much more durable and reliable than the wet-clutch Punch CVT.
The Honda City temporarily reverted to conventional automatic before returning to CVT.
Besides Proton, the GD8 Honda City also used a CVT with a start-up clutch. That's why the GM2 reverted to a 5-speed conventional auto gearbox. From the GM6 onward, the Honda City returned to CVT.
Summary
CVTs are reliable transmissions provided you use them the right way - drive like a normal person, conduct regular maintenance, use the right fluids. They are not meant for abuse.
Common fears of overheating CVTs and snapped CVT belts can be avoided with the right measures. Not all CVTs are made the same and some are better than others.
Previously an engineer in an automotive manufacturing company and a highway concessionaire. A part-time research student on biofuels and diesel engines. Obsessed with vehicle electrification and the future of transportation.