Everything You Need to Know About the CVT Gearbox
Single-speed, shiftless, and stepless — these are 3 words that we can use to describe the CVT gearbox, but what do they really mean? What do the letters “CVT” even mean? Many popular car models in the world today are fitted with CVT gearboxes, but how much do we even know about what we are buying?
In today’s blog, we are taking a closer look at the CVT gearbox and transmission, what sets it apart, how it works, its advantages and disadvantages, and so on. If you’ve ever wondered about the CVT before, then this is the only blog you’ll need to understand it.
What is a CVT?
A Continuously Variable Transmission, or CVT for short, is a type of gearbox and transmission unit that uses an unending selection of working gear ratios as you’re driving along. As you likely already know, the typical mechanical transmission has a fixed number of gear ratios.
Many modern manual transmissions are 6-speed, for example, and automatics run from 6-speed all the up to 10-speed and sometimes more. Regardless, they work within that fixed number of gear ratios, whereas the CVT is a single-speed unit that works through as few or many ratios as it needs when you’re driving.
While some may perceive CVTs as a relatively new concept, they are not. The very first CVT was actually designed by none other than Leonardo DaVinci back in 1490, and was then patented almost 400 years later by Daimler and Benz in 1886. By 1910, the CVT was used in a Zenith Motorcycles model that was so efficient at uphill riding, it had to be banned from competitions.
In cars, the CVT entered the automotive mainstream, most famously used by Subaru but then by many major OEMs. Just about every major OEM now has at least one model in their range that includes a CVT option. Most often, it’s the more basic level standard trims that are equipped with it.
How Does a CVT Work?
So, what makes the CVT work in that single-shift and stepless way that it does? How is it able to work outside of any gear ratio limit? CVTs use a simple system of pulleys and cones all connected with a chain belt. As the cones move, the belt’s diameter increases or decreases to create a change in gear ratio. Since it doesn’t have to work toward any specific gear ratio, the shifts are smooth and near instant, which brings numerous benefits (see further below).
Inside the CVT, one of those pulleys is connected to the engine and the other shifts drive power to the wheels as needed. There is one other kind of CVT that achieves the same effect but using a system of discs and rollers. While it sounds different in that respect, it’s actually the exact same principle, just using slightly different parts.
Why Do Some Automakers Favour CVT Gearboxes?
We mentioned earlier the idea that many perceive the CVT as being new, and yet it’s centuries old. If that’s the case, why hasn’t it been used sooner? Why was it only in the 1980s and 1990s that we saw the CVT emerge into the mainstream? OEMs have come to favour the CVT for some of their models because it’s an ideal solution when creating a budget-friendly car for the average consumer.
CVT units are smaller and lighter, offer smooth and simple gear shifts, improve fuel consumption efficiency, and more. In other words, it worked as an ideal transmission unit to offer in small-engine cars, which in places like the UK and mainland Europe have always been very popular for their affordability and efficiency. The CVT is a great complement to that type of car.
Pros and Cons of the CVT
Next, let’s look at the advantages and disadvantages of using a CVT. So far it all sounds great and full of benefits, but there are definite limitations to the technology as well. Let’s take a closer look:
Pro: Greater Fuel Economy
The first and most important benefit — especially at the time of writing this blog where petrol and diesel prices are skyrocketing — is that the CVT makes a car more fuel efficient. By offering smooth transitions between gears, and also being lighter in weight, all contributes to this transmission helping to improve fuel economy. It’s the main reason OEMs most often use CVT gearboxes in their hybrid vehicles.
Pro: Uphill Driving Made Easier
Earlier we mentioned a Zenith motorbike that was disqualified from uphill racing because of its CVT. That’s because the CVT doesn’t have to work anywhere near as hard as a regular transmission when travelling uphill. The CVT can find the needed gear ratio almost instantly, whereas a regular automatic can take time and struggle to get to the ideal spot. It’s even harder with manuals if you don’t know what you’re doing.
Pro: Smoother Driving Experience
Not every driver wants the “launch” experience offered by some high-end car brands and their sporty sedans and coupes. If you’re driving a family car where kids are trying to sleep in the back, or after you’ve had a tough day at work, what you really benefit from is a smooth drive. This is what the CVT delivers. There are no jerks from shifting gear ratios, and no abrupt downshifting either. It’s all just smooth and even sailing.
Pro: Smaller and Lighter
Finally, as we mentioned in the earlier point, the CVT is lighter and smaller than a conventional transmission because it doesn’t require all the gears and heavy components that make up a traditional model. This is a big part of what makes it more fuel efficient.
Con: Higher Repair and Replacement Costs
Unfortunately, despite being lighter, smaller, and even relatively simpler in its construction, it is absolutely not cheaper to repair or replace. If your CVT does break down completely, you could be looking at a very hefty repair bill, possibly around £4,000. What’s more, the CVT is not as durable or long-lasting as a traditional transmission either. You could be lucky to get 100,000 miles from a CVT.
For these reasons, regular and proper servicing and maintenance are essential if you’re driving a car with a CVT gearbox.
Con: No Good for High-Specification Cars
Next, we mentioned that many OEMs like to use CVT gearboxes for hybrids, as well as for base-level trim cars. The reason for this is that the CVT is entirely unsuitable for high-specification cars. Those with high horsepower ratings don’t work well at all with the CVT unit. Therefore, if you like the idea of a CVT transmission — which many do — you have to settle for a lower-specification car.
Con: Strange Acceleration Noise
Finally, one complaint people have about the CVT is for the unusual noise it makes when accelerating. It’s an entirely different noise pattern to when you’re driving a car with a more traditional transmission setup. There seems to be a lot of engine work early on which makes noise as the car gets going. It also contributes to the idea that CVT acceleration, while smooth, is also sluggish.