CVT gearbox explained: how it works, what is normal and what points to a fault

A CVT gearbox is an automatic gearbox without fixed gears. A steel push belt or chain runs between two adjustable pulleys, so the ratio changes steplessly. The car drives without any gear changes and the engine stays at an efficient speed. CVT stands for continuously variable transmission, and “stepless automatic” means the same thing.

Even so, the CVT has a mixed reputation. You read about whining, slipping and expensive overhauls, and you cannot tell whether that applies to your car. That depends on the type of CVT, the maintenance and how the car has been used. A Nissan with Xtronic, an Audi with Multitronic and a Toyota hybrid with an e-CVT are three technically very different gearboxes.

On this page you will learn how a CVT works, which versions exist, how to tell normal CVT behaviour from an early fault and what to do if something is wrong. ATR Transmissies in Montfoort, in the Dutch province of Utrecht, is a transmission specialist that works on CVTs as well as other automatics. Our starting point: first find out what is going on, only then replace parts.

What is a CVT gearbox?

A CVT gearbox has no first, second or third gear. At every moment it picks the ratio that suits your speed and how far you press the accelerator, and it slides between ratios without steps. So yes, a CVT is an automatic: there is no clutch pedal and you do not change gear yourself.

A conventional automatic jumps from gear to gear, and you feel that as a gear change. A CVT glides through all its ratios. People and carmakers use many names for it: CVT transmission, CVT automatic, stepless automatic, or a brand name such as Xtronic, Multitronic or Lineartronic. The principle is always the same.

Not sure whether your car has a CVT or another kind of automatic? Read how to tell which automatic gearbox you have, or see our overview of all types of gearbox.

How does a CVT gearbox work?

A CVT gearbox works with two pulleys: one on the engine side and one on the wheel side. Each pulley consists of two cone-shaped discs that can slide towards and away from each other. A steel push belt or chain runs between them. When the discs move together, the belt rides further out and the working diameter grows. When they move apart, the belt drops inwards.

When you pull away, the belt runs on a small diameter on the engine pulley and a large diameter on the wheel pulley. That works like a low gear. As your speed rises, the ratio gradually shifts the other way. The electronics control this with hydraulic pressure, based on inputs such as road speed, accelerator position and engine speed.

Push belt or chain

Most CVTs use a push belt. According to Bosch, which makes these belts, a push belt consists of hundreds of steel elements threaded onto two packs of thin steel rings. The elements push each other forward and the rings hold them together. Torque passes through friction between the elements and the pulleys. That is why the quality of the fluid in a CVT matters so much: it has to provide exactly the right friction.

Some manufacturers chose a chain instead. The Audi Multitronic and the Subaru Lineartronic use a steel link chain that transmits the power by pulling rather than pushing. The principle with the adjustable pulleys stays the same.

Pulling away: torque converter or multi-plate clutch

Like every automatic, a CVT needs something to disconnect the engine when you are standing still. That differs per type. CVTs from Jatco (including the Nissan Xtronic) and the Mercedes-Benz Autotronic use a torque converter with a lock-up clutch. The Audi Multitronic has no torque converter but wet multi-plate clutches for forward and reverse. Honda’s Multimatic also works without a torque converter.

That difference matters when there is a complaint. Shuddering when you pull away gently can come from the torque converter lock-up in one CVT and from a worn starting clutch in another. If you do not know which design you are dealing with, it is easy to replace the wrong part.

From Variomatic to push belt: a Dutch invention

The CVT in passenger cars started in the Netherlands. Hub van Doorne designed the Variomatic for DAF, and it was presented in the DAF 600 at the Amsterdam motor show in 1958. That first version used rubber V-belts. Volvo later used the Variomatic in the 66 and the 340.

The steel push belt was developed afterwards at Van Doorne. The 1970 patent is in the names of Hub van Doorne and DAF engineer Hemmo Ludoph. The company Van Doorne’s Transmissie in Tilburg became part of Bosch in 1995. So the push belt you find in many CVTs today descends directly from a Dutch invention.

CVT vs automatic: what is the difference?

The difference lies in how the gearbox changes the ratio. A conventional torque converter automatic changes between fixed gears using planetary gear sets. A CVT has no fixed gears and changes the ratio steplessly. A dual-clutch gearbox (DSG or DCT) does have fixed gears again, but swaps between them with two clutches.

More about the conventional automatic is in how an automatic gearbox works. The technology behind DSG and DCT is in our article on the dual-clutch transmission (DCT).

Is an e-CVT the same as a CVT?

No. The e-CVT in hybrids from Toyota and Ford, among others, has no push belt and no pulleys. A planetary gear set divides the power between the petrol engine, a generator and the electric motor. By controlling the speed of the electric motors, the system creates a stepless ratio. It feels like a CVT to drive, but the wear points are completely different. How such a system works is explained on our page about the Ford HF35 e-CVT.

There is variation within ordinary CVTs too. In 2018 Toyota presented the Direct Shift-CVT: a CVT with a fixed launch gear for pulling away, after which the gearbox switches over to the belt. Complaints and causes per Toyota gearbox are on Toyota automatic gearbox problems.

Pros and cons of a CVT gearbox

A CVT gearbox is comfortable and can be economical, but it needs proper maintenance and does not suit every driving style. Here is the honest balance.

Advantages

• No gear changes. The car accelerates evenly, without the brief interruption of a gear change.
• The engine stays in a favourable rev range. The gearbox can keep the engine in its most economical or most powerful band, depending on what you ask of it.
• Calm in town and in traffic jams. Creeping along and pulling away at traffic lights feels fluid.
• Compact design. A CVT does not need a set of fixed gears for every ratio.

Disadvantages

• The rubber-band effect. Under hard acceleration the revs shoot up and stay there while the speed only catches up afterwards. It sounds as if the clutch is slipping, but it is part of how a CVT works.
• Sensitive to fluid quality. Because the power passes through friction, the lifespan depends heavily on the correct, clean CVT fluid.
• Limits on torque and towing. Not every CVT is built for heavy trailers or lots of towing. The permitted towing weight differs per version.
• Heat. Long periods of heavy load, such as climbing with a caravan or a long traffic jam, push the fluid temperature up. A CVT can then step in with reduced power or a limp mode.

So why do some people say you should avoid a CVT? Mostly because of the last three points, and because some CVT generations have a clear history of known faults. A well-maintained CVT that is driven within its limits is a different story.

Which cars have a CVT gearbox?

CVT gearboxes are found mainly in Japanese brands, but Audi and Mercedes-Benz have built them too. Almost every brand gives its CVT its own name. These are the gearboxes you come across most often, with the page where we go into the complaints in more depth.

Note that one brand can use several kinds of automatic. A 2019 Nissan Qashqai with the 1.3 DIG-T engine, for example, has a dual-clutch gearbox rather than a CVT. The gearbox type depends on model, engine and year.

CVT gearbox problems: normal behaviour or an early fault?

Most CVT gearbox problems start small: a shudder when pulling away, a soft whine, revs that climb a little too far. The tricky part is that a healthy CVT already sounds different from what you may be used to. Use this table to judge what you are noticing.

Do not keep driving for long with a complaint from the right-hand column. That applies more strongly to a CVT than to many other gearboxes. If the belt slips over the pulleys, it damages the surface of the discs, and fresh fluid will not undo that damage afterwards.

A limp mode or warning light leaves fault codes behind. What those codes can mean is in our overview of transmission fault codes. If your automatic jerks or changes badly in general, also see automatic gearbox not shifting properly.

Known problems by brand

Some CVTs have their own well-documented pattern of complaints. With the Nissan Xtronic it is often judder, whining and overheating; read more on Nissan Qashqai automatic problems and Nissan Note problems. The Audi Multitronic has its own weak points in the clutches and control unit, which we discuss on the Multitronic page. If you drive a Mitsubishi, see Mitsubishi ASX problems.

CVT maintenance in brief

The most important maintenance on a CVT gearbox is the fluid. It does more than lubricate and cool: it decides the grip between belt and pulleys. Dirty or incorrect fluid changes that grip, and then the belt can start to slip.

Two things we want you to take away:

• Only use the specified CVT fluid. CVT fluid is not ordinary automatic transmission fluid (ATF). Nissan, for example, specifies its own CVT fluids (NS-2 or NS-3, depending on the gearbox) and warns that ATF can damage a CVT. The CVT fluids are not interchangeable with each other either.
• “Maintenance-free” does not mean the fluid lasts forever. Some manufacturers describe a fill for the life of the gearbox. With heavy use, lots of short trips, traffic jams, towing or mountains, the fluid has a harder life. That is why we prefer to measure the condition of the fluid rather than assume it is still fine.

Intervals, how a fluid change is done and whether flushing makes sense are covered on our page about CVT maintenance. General information about gearbox oil is on changing gearbox oil.

Driving a CVT: towing, mountains and traffic jams

You can take a CVT on holiday without any problem, as long as you stay within the car’s limits. Heat is the biggest enemy. The main points to watch:

• Caravan or trailer. Check the maximum towing weight of your exact version. In the Netherlands you will find it in the RDW vehicle registration data for your registration number, and it is also in the owner’s manual. It differs per engine and gearbox.
• Mountains. On long descents use the mode the owner’s manual recommends (often L, B, S or the manual mode), so the engine helps with braking and your brakes and gearbox stay cooler.
• Traffic jams and heat. If the warning light comes on or the power drops, stop somewhere safe and let the gearbox cool down. Do not keep driving in limp mode.

More tips for driving in the hills and mountains are in driving an automatic in the mountains.

Are CVT gearboxes reliable, and how long do they last?

A CVT gearbox is as reliable as its type and its maintenance. There is no fixed mileage that every CVT reaches. Three factors make the difference: the design of the gearbox (some generations have clearly more known faults than others), the condition of the fluid and the way the car is driven.

A CVT that has been driven gently all its life and received fresh fluid on time can last a long time. A CVT that ran on worn-out fluid for years, was often heavily loaded or kept driving with a slipping belt will fail sooner. Whether a CVT or a conventional automatic lasts longer therefore depends more on the specific gearbox and its history than on the principle. Buying a used car with a CVT? Ask about the transmission maintenance and, if in doubt, have the gearbox read out and test-driven by someone who recognises CVT complaints.

CVT overhaul or repair: what is really needed?

A failing CVT does not automatically mean a full overhaul. The right job depends on the cause, and you only know the cause after a diagnosis. Broadly, there are four routes:

1. Fluid and settings. Sometimes the complaint comes from old fluid, a low fluid level or adaptation values in the software. A fluid change, a top-up or a relearn can then solve it, provided the mechanical parts are still healthy.
2. Targeted repair. A faulty sensor, a problem in the hydraulic control or a leak can often be fixed in a targeted way, without taking the whole gearbox apart.
3. Overhaul. With wear on the belt or chain, pulleys or bearings, the gearbox comes out of the car and is fully dismantled. Worn parts are replaced, and the gearbox is rebuilt and tested.
4. Remanufactured exchange gearbox. If the damage is extensive or an overhaul does not make sense for your type, a remanufactured gearbox can be an option.

What a CVT overhaul or repair costs depends on the type of CVT, the cause, the extent of the damage, the availability of parts and whether the gearbox has to come out of the car. A fixed figure without a diagnosis therefore says little. The factors are explained on gearbox overhaul cost. Contact us for a price indication based on your registration number and complaint.

How ATR Transmissies handles a CVT complaint

We understand that you want certainty about what is wrong with your car before you spend money on a repair. With a CVT that matters even more, because the same complaint can come from the fluid, the control system, the starting clutch or the belt. That is why we work in three steps:

1. Book your car in. Send us the registration number, the complaint and any fault codes. We review the request and schedule the car.
2. Independent basic diagnosis. Our transmission specialists read out the gearbox, check the condition of the fluid and look for leaks, and take a test drive to experience the complaint themselves. You get substantiated advice on the possible next steps. If the high revs are simply normal CVT behaviour, we tell you that too.
3. Drive with peace of mind. Based on the diagnosis we discuss what is needed. Once you agree, our specialists get to work. Afterwards we test the car and carry out a thorough final check.

Our position is simple: measure first, replace later. We only repair what is actually needed, and often in a targeted way rather than swapping the whole gearbox. We also make some of the parts ourselves and do our own research into materials and tolerances. You can read more about who we are on about ATR (in Dutch).

For garages: stuck on a CVT complaint? You can book the car in with us or have the diagnosis done remotely with ATR Remote. That way you can keep helping your customer, even when the transmission goes beyond what your own workshop can handle.

Frequently asked questions about CVT gearboxes

Does CVT mean automatic?

Yes. A CVT is a type of automatic gearbox: there is no clutch pedal and the car chooses the ratio itself. Unlike a conventional automatic it has no fixed gears, so you feel no gear changes. Some CVTs simulate steps or offer a manual mode with paddles, but underneath the ratio still changes continuously.

Are CVT gearboxes reliable?

That depends mainly on the type of gearbox and the maintenance. Some CVT generations have many known faults, others clearly fewer. A CVT that gets the correct fluid on time, is not routinely overloaded and is checked at the first complaint is, as a rule, a dependable automatic.

How long does a CVT gearbox last?

There is no fixed mileage. The lifespan depends on the design, the condition of the fluid, the load (towing, mountains, traffic jams) and how quickly a complaint is dealt with. Driving on with a slipping belt shortens the life considerably, because the pulleys get damaged as well.

Should I change the fluid in my CVT gearbox?

Yes. Even if the manufacturer calls the gearbox maintenance-free, it is sensible to have the fluid checked and changed when needed. CVT fluid decides the grip between belt and pulleys. Always use the specified CVT fluid, never ordinary ATF. Intervals and method are on CVT maintenance.

Does a CVT gearbox have a clutch?

A CVT has no clutch pedal, but it does have a part that disconnects the engine when you stop. In most CVTs that is a torque converter with a lock-up clutch, as in the Nissan Xtronic. The Audi Multitronic uses wet multi-plate clutches for forward and reverse, and Honda’s Multimatic also works without a torque converter.

Is it normal for a CVT to rev high?

Under hard acceleration, yes. A CVT then holds the engine at high, steady revs while the speed rises evenly; that is the rubber-band effect. Revs that shoot up while the car barely accelerates are not normal. That points to slip and deserves a diagnosis.

Are CVT gearboxes noisy?

A healthy CVT can drone under hard acceleration because the engine holds high revs, and that is normal. A whine or hum that rises and falls with road speed is not. That usually points to bearings, worn pulleys or a worn belt, and sometimes to a wheel bearing outside the gearbox.

Are CVT gearboxes good for towing?

They can tow, within the permitted towing weight of your exact version. In the Netherlands that figure is in the RDW registration data and in the owner’s manual, and it differs per engine and gearbox. Watch out for heat: long climbs with a heavy caravan put a lot of strain on the CVT fluid.

Which is better, CVT or AMT?

A CVT is smoother, with no gear changes you can feel, which makes it pleasant in town and in traffic. An automated manual (AMT) is mechanically simpler and efficient but pauses at every gear change. The CVT asks more of its fluid and maintenance. Which suits you depends on how you drive and how well the car has been looked after.

What is the biggest killer of a CVT?

Heat and old or incorrect fluid. Both change the friction between belt and pulleys, which can make the belt slip, and slip damages the pulley surfaces. Long climbs with a caravan, long traffic jams and fluid that has never been changed all add up. Driving on once a complaint appears makes it worse.

How much does it cost to replace a CVT gearbox?

That depends on the type of CVT, the cause and extent of the damage, the availability of parts and whether the gearbox has to come out. Sometimes a targeted repair is enough and replacement is not needed at all. The factors are explained on gearbox overhaul cost. Contact us for a price indication based on your registration number and complaint.

Know your CVT, and do not wait too long

A CVT gearbox is a stepless automatic that works with pulleys and a push belt or chain. It drives smoothly and can be economical, but it is more sensitive to fluid, heat and driving on with a complaint than many other gearboxes. The rubber-band effect is normal; slip, judder, whining and limp mode are not.

Know which type of CVT you have, have the fluid checked in time and get a complaint looked at before the pulleys are damaged. Not sure whether what you hear is normal? Find out what your symptom could mean, or book your car in with ATR Transmissies. We start with an independent basic diagnosis and tell you honestly what is and is not needed.

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