The function of a car's transmission is fairly straightforward: it makes sure that the appropriate amount of engine power goes to the wheels to drive at any given speed. It's similar to riding a multi-speed bike—if the chain comes off, you're not going anywhere and if you're in a high gear, you'll find it difficult getting started from a stop. It's vital to the engine, and if not properly maintained, you could see a drop in fuel economy and even eventual engine failure. And while they all serve the same purpose, there are a few different types of transmissions.
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One of the most important parts of a vehicle, the car transmission is essentially the "gearbox". Typically, there are five to six gear sets and a series of gear trains, all of which allow the driver to control how much power is transferred to the vehicle itself. The transmission helps determine the rate at which the car engine spins. The absence of a transmission would make it very difficult to both control and safely maneuver the car.
In a car transmission, the gearbox is the second stage of the entire system. It is essentially part of the core building block of modern cars. The gear itself uses interlocking teeth to connect small, fast-moving parts to larger gears that have more teeth. It's that larger cog that rotates to adjust and control the car's speed. The complexity of the gearbox is why it's one of the most critical parts of the car's engine.
Cars are continuously evolving, improving and becoming more efficient. That goes for the car transmission as well. There are three types of transmissions in use:
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Manual transmissions
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Automatic transmissions
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CVT transmissions
Each type of transmission is geared toward specific needs and driving styles. More modern vehicles typically have either manual or automatic transmissions.
The manual transmission is the original type of transmission. It's also called the standard transmission, but there's a good chance you'll know it as the stick shift. This type of transmission has the driver using a clutch pedal to control the torque transfer from the engine to the transmission, manually shifting between gears as necessary.
Mechanically, manual transmissions are the simplest type of transmission and often last longer than other types—simply put, there's less that can go wrong. The only major disadvantage to a manual transmission is the learning curve: These types of vehicles require more concentration and maneuvering than other transmissions.
Yes, manual transmissions are mechanically simpler, but with the caveat of being harder to operate. If a driver doesn't have the time to take on the extra work that comes with driving a stick shift, then they're best suited for choosing to drive an automatic transmission vehicle. This type of transmission automatically changes gears as the vehicle moves, leaving the driver to focus more on the road, rather than shifting the clutch. Once a car is in drive, its computer takes over the transmission, shifting between gears as necessary while the car accelerates and decelerates.
You've probably heard the sound of your engine getting higher, but then the sound drops as you continue to accelerate — that's your car moving from a lower to a higher gear. Most automatic transmissions have between five and ten gears— and the more gears your transmission has, the better it will perform at different speeds. A transmission with more gears means a vehicle has a wider range of speeds where it will perform optimally and lead to better overall fuel economy.
While easier to use, automatic transmissions have more complex parts, and therefore, are more prone to failures. And automatic car transmission repair or replacement can get very expensive.
The more gears a car transmission has, the better it will operate over a wide range of speeds. But what's the limit when it comes to the number of gears a transmission can have? Thanks to the continuous variable transmission (CVT), there is a continuous— or limitless— amount. It's also known as the shiftless car transmission, and unlike other types, the CVT transmission doesn't use gears as a means for producing varying speeds, but instead relies on a belt-driven design of two rubber or metal pulleys. The two pulleys work in sync, mimicking the effect produced when gears of different diameters are engaged. The pulleys' ability to increase and decrease their effective diameters allows the CVT transmission to move fluidly through a limitless range of effective gears.
The CVT transmission isn't new: It's been around for decades, rising in popularity among Japanese and European manufacturers in the mid-2000s. If you're looking for a car with a CVT transmission, you'll need to do some research. Most new cars will state the type of transmission they have on the window sticker. If you're buying a pre-owned car, some online research will help to determine the type of transmission a certain make and model has installed.
Although CVT transmissions offer a limitless range of gears and superior fuel economy, they do have their limits. This type of transmission is not suited for off-road environments, due to its limited torque-handling ability. Another drawback is that CVT transmissions cannot provide engine braking. Because of their complexity, these transmissions routinely require more maintenance and repairs can be costly. Over time, the belts can break down due to excessive wear and stretching. When you're searching for a shop to work on your transmission, be sure to check if they're able to work on CVT transmissions—going to a dealer facility is a good option as well, though it will be expensive.
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Regardless of the car transmission type, all car gearboxes work similarly. There is a gear lever that selects, advances and enables the gears to connect to one another. In a car with a manual transmission, the driver physically operates the lever with the clutch control or clutch pedal. Alternatively, it shifts automatically in an automatic transmission.
When engaged, the gear itself maneuvers clutch plates into place, which in turn connects to larger gears. These larger gears are connected to the vehicle's differential. When in motion, the lever enables different gears to connect at different times. In turn, there are sets of gears that adjust the gear ratio, or the power ratio transmitted from the engine to the wheels of the car.
No matter the type of transmission your car has, it relies on transmission fluid to keep it functioning properly. Routinely checking the transmission fluid is vital to your transmission's overall health and could also be an early indicator of problems.
To check your transmission fluid, first, consult your car's manual to see whether or not your car needs to be running when you check the fluid. This varies from car to car, with many manufacturers requiring the car to be running for an accurate check.
Your transmission fluid dipstick will be under the hood, similar to the oil dipstick—be sure not to mix up the two. If you're unsure which is which, check your manual. Remove the dipstick, clean it and repeat the process. Check the level as indicated on the dipstick. If your fluid level is low you can easily top it off, but be sure not to overfill it: Too much fluid could damage your transmission. A low fluid level is a telltale sign of a leak—look for a puddle of red liquid under the front of your car.
When it comes to changing your car's transmission fluid, manufacturer recommendations can range from every 30,000 to 100,000 miles. Factors like how hard you push your car, if you're frequently in start-and-stop city traffic or pulling a trailer are all good reasons for more frequent transmission fluid changes.
If you're leasing a new car for a few years, chances are you won't ever have to bother with the transmission. On the other hand, if you've just purchased a pre-owned car with 60,000 miles on it, it may be due for a transmission fluid change.
When checking the fluid, inspect the color. It should be light pink or red, and translucent enough to easily see through it. If the fluid is dark or you can see dirt or debris in it, it has either become degraded and needs changing or there are possible transmission problems. If you detect a burned odor, your transmission may be overheating, and the smell of gas, oil, or coolant could indicate a leak in the system.
Changing your transmission fluid isn't a simple process and not something you should do at home. The vehicle needs to be lifted, the pan dropped, and the fluid poured out. Manual transmissions are somewhat simpler, but still require the vehicle to be lifted. Most CVT transmissions require routine fluid changes, and many new cars have transmissions that are nearly sealed shut or require a dealer's service computer to get proper diagnostic readings.
Thankfully, a well-maintained car won't need transmission fluid changes very often, but when it is necessary, you should find a transmission shop where the average cost to change transmission fluid is around $150 to $250. A technician at a transmission shop will also be able to determine if your transmission needs to be flushed. This can be especially important in high-mileage cars: A transmission flush will dislodge buildups of sludge and other contaminants that could otherwise lead to a clog in the system. Normal transmission fluid changes won't remove these buildups.
As one of the most expensive repairs to any vehicle, it's pretty important to catch any issues early on. It's natural for a transmission to experience wear and tear over time and proper maintenance can help with extending the life of a car transmission.
Here are some common signs there may be a problem with your car's transmission:
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Transmission shifting delays
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Transmission slipping, grinding, or jumping acceleration when shifting gears
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Car shaking at any speed
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Burnt smell underneath the car hood
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Fluid visibly leaking from the car
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Clunking, screeching, or whistling sounds coming from the car
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Cloudy, thick, or unpleasant smell of transmission fluid on dipstick
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Manual transmission gear shifter is physically hard to maneuver, or won't get into gear
The easiest way to extend the life of your car's transmission is to keep up with routine maintenance, frequently check your transmission fluid, and have it changed or flushed when necessary. When getting an oil change, be sure to ask your mechanic to check the transmission fluid as well. If neglected, a failed transmission is a very expensive problem to remedy.
The cause of a failed transmission is usually hidden deep within the component, and even though transmission repair is an option, a replacement is often more cost-effective. The process of removing a transmission itself is incredibly complicated and time-consuming.
Car transmission repair or replacement can take anywhere from five to fifteen hours of labor. A refurbished transmission can cost around $2,000, while a new one could set you back $5,000 or more—and that's before factoring in troubleshooting and labor charges.
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Keeping up on regular car maintenance and routinely checking your transmission fluid can save you from the incredible expense and hassle of replacing your transmission. Luckily, managing and paying for your car's maintenance, planned and unplanned, is easy with the Synchrony Car CareTM credit card for all your automotive expenses. Learn more here.