What are the major factors you consider while you choose a car? Purpose, like for family or professional and personal use, budget, aesthetic appeal, powertrain, space, performance and price are some. A very important feature to consider over the last decade and a half, has been the type of transmission available in the cars. According to recent trends in the automobile market, since 2007 there has been a huge surge in the sales for cars with automatic transmission in the US. As a result, the manual or stick-shift cars have been on a decline; according to a CNBC report, manual cars comprise around 2% of all the cars sold in the USA in 2019.
For the purist petrolheads, let’s face it. Few things are as exhilarating as throwing a stick shift car around corners at speed on a tight winding road, at the edge of grip. Will we still be able to do this in future?
Among the most critical of your car’s mechanical components, transmission is basically a box with gear cogs of various sizes, the reason it is called a gearbox. The purpose of transmission is basically to transfer the power from the engine to your wheels and help the car move. The series of gears, work in specific ratios to maintain the speed of the vehicle. The gearbox ensures a balance between the speed of the wheels and the speed at which the engine rotates through these gear ratios. So, the lowest gear is generally the most powerful of all forward moving gears and provides less speed but the higher gears help in achieving higher speeds at lower rpms, due to higher gear ratios.
In this post, we will talk about briefly about the development of automatic transmission, compare to manual transmission (the benefits and downsides), the types of automatic transmissions and how they have become the major type of transmission available, essentially making stick-shift an obscure thing of the past.
Manual transmission or stick-shift transmission systems, as the name suggests is controlled manually. There is a gear lever or stick linked and sitting on the top of the gearbox, just next to the driver’s seat which is used to shift gears as the driver accelerates and decelerates. Along with this, there is a manual clutch pedal that works to engage and disengage the power transfer. To explain better, when the clutch pedal is pressed down, it disengages the gearbox from the powertrain, thus stopping power flow from the engine to wheel. This allows the time to shift gears. As you release the clutch pedal, the transmission again links up and allows power to flow to the wheels.
Talking about their ways of operation, it has remained similar from the early 4-speed manuals to the latest -generation 6-speed slick shifting gearboxes. The transmission is linked to the clutch plate housing in the front of the car while with the engine at the back, for most cars. For some cars like those with FWD designs, the gearbox, along with the engine and drive axles are one single unit. In those designs the transmission also is bolted with the front wheel axles.
The gears in the gearbox shift and regulate the speed of rotation of the wheels against the speed of rotation of the engine. The lower gears provides a lot of torque and helps the engine to generate a lot of power to speed. Quite contrarily, for engines of high-performance cars, like the inline 6-cylinders or V6, V8, V10 and V12 engines , the peak torque is generated in the higher reaches of the powerband i.e. past 9000 rpm. This helps in gaining supreme acceleration and providing peak levels of power at top speeds.
Automatic transmissions were introduced long after any manual ones, the first one in 1921. The first automatic was invented by Alfred Horner Munro in 1921, but never became succesful due to lack of power and use of compressed air. The first type which came into prominence was made by a pair of Brazilian engineers, using hydraulic fluid in place of air. The design was later sold with full rights to General Motors and this was the Hydra-matictransmission, introduced in 1940. This was first used in the 1948 Oldsmobile model. It had several upgrades over the next decade and paved way for the the failed JETAWAY in 1955 and the Turbo- Hydramatic in 1969. Most modern TCV and AMT gearboxes use two major features of this transmission till date, hydraulic pressure and planetary gears, i.e. two gears mounted in such a way, that the center of one revolves around the center of other.
Currently there are four basic major types of automatic transmission:
Torque Converter (TCV)
This is the traditional and most common form of automatic transmission, the hydramatic transmission was a precursor to this. It is basically a type of hydraulic fluid coupling, connecting the engine to the gearbox. The difference between a torque converter and a traditional fluid coupling is the presence of a stator, which regulates the pressure and speed of flow of the hydraulic fluid between the turbine (revolves slowly at the start) and the impeller (revolves very quick). It provides various levels of low-end torque at low rpm(revolutions per minute) aiding in smooth starts and acceleration. This enables the car to transit very quick and efficiently from standstill to motion and with increase in engine speed the stator actually stops and the transmission behaves like a normal fluid coupling. The only disadvantage of TCV is that they have a high chance of slipping gears once past the low rpm or idle range. This makes torque converter gearboxes notchy and less efficient than most manuals. Damaged clutches and contamination of fuel are among other common problems. Although, with time and superior technology like synthetic fluids, “lock-up” systems and better stators, companies have managed to make some excellent torque converter gearboxes, like the 8L90E heavy-duty gearbox featured in the Chevrolet Corvette Z06, car which puts out 650 hp and 650 pound feet of torque.
Automated Manual Transmission (AMT)
Made famous by the venerable Volkswagen Beetle’s 3-speed Autostick transmission or the 1967 Porsche 911’s 4-speed Sportomatic , this is what we also call the semi-automatic or clutchless manual transmission. Here, the driver controls the gear shifts themselves while the clutch is engaged/disengaged electrically, electro-pneumatic or by hydraulic methods. And surprisingly, all of these happens in a matter of milliseconds. Newer and most of today’s AMT gearboxes although, are fully-automatic, where clutch engagement and disengagement, matching of revs, power transfer to wheels and gear shifts are all controlled by the TCU and electronic sensors. A majority of these have the provision of shifting one gear up or down at a time, but few advanced ones feature shifting of multiple gears as well, coming with paddle shifters. The older models, still come with a stick which shifts conventionally, has a shift gate and an electronically controlled clutch. AMTs have added advantages over both TCV and manual gearboxes. They are much more fuel efficient compared to torque converter units while offer a hassle-free and simple driving experience compared to manuals, as there is no need to think of whether your revs are matching or are you nearing the redline. They are also the cheapest automatic transmission types available in the market, although much more tha manuals. They retain an option for manual- loving enthusiasts, so you can actually shift manually and ‘drive’ the car, rather than just ride.
The issue with AMT gearboxes are that they tend to be jerky and are not always slick-shifting. The gear shifts are computer-controlled and thus happen at fixed rpm(s). So, the option of a quick downshift while overtaking or riding up an incline is not the easiest of tasks. Although, mostly AMTs have been developing a lot, but they have been well-replaced by the use of the modern, dual-clutch systems, in developed countries like USA.
Some of the best AMT gearboxes in some famed cars, include Ferrari’s 1989 640 F1 car with a 7-speed clutchless transmission, the 1997 Ferrari F355’s 6-speed gearbox with paddle shifters, BMW’s SMG 6-speed and 7-speed transmission on their performance-packed M-series coupes and Lamborghini’s 6-speed, E-Gear in the Gallardo and Murcielago and ISR in the Aventador and Venono supercars. Due to low costs, AMT has been used by several mass-segment cars like the Honda’s Civic and Jazz, Fiat Punto, Suzuki Celerio and Swift, Toyota Yaris and VW Fox.
Dual-clutch transmission (DCT)
Quite similar to the name, this transmission type has two separate clutches for handling gears (one for the odd pair and another for the even pairs). This is the pinnacle of automatic transmission till date and are a huge upgrade over AMT or torque converters. And as they sound they come with double the benefits. Knowing the functioning of a DCT, it is just like two manual transmissions with separate clutches for odd and even pair of gears in one single gearbox unit. In DCT system’s, if your car is in a particular gear, the clutch for the other is pre-selected when up-shifting or downshifting. So, during shifting, the sensors actually engage one clutch as they disengage the other. This reduces shift time drastically, making DCT systems really slick, and also prevents loss of torque while maintaining higher fuel efficiency figures. Most purists will hate that, but most supercars and high-performance cars are equipped with DCT gearboxes in the current generation, as no manual can match their shift speeds and quick torque restoration. Ferrari shifted to DCT in 2009 with the 458 Italia and stopped making their renowned manual transmission systems. Lamborghini, British manufacturer Mclaren and even the highest spec Porsche cars have taken to DCT. Clutches in DCT are like motorcyle clutches, either wet or dry. The difference is wet clutches are bathed in oil, which act as coolant, in case of cars with high torque outputs like the BMW M8, Nissan GT-R or Ferrari 488 Pista.
DCT was used at first in trucks and tractors. Porsche started working on DCT gearboxes in 1970s and by 1983 had used their first dual-clutch system called the PDK (Porsche Doppelkupplungsgetriebe) in their Porsche 956 model. Three years later, it won the World Sportscar Championship in Le Mans using the transmission. DCTs were made popular in the consumer market by the 2003 VW Golf. Marketed as DSG gearboxes, these were really quick shifting and took the market by storm. ALthough these systems by VW are good and quick, they are still a notch below the extremely aggressive shifting DCT systems used in supercars like McLaren 720s Spyder, Ferrari 488 Pista, Lamborghini’s Huracan Performante.
There are no obvious disadvantages of DCT, except their high price. Also DCT gearboxes are not made by many manufacturers. BorgWarner is the most popular manufacturer of DCT gearboxes, designing them for multiple companies, including VW group’s DSG gearbox and those for the 2009 Nissan GT-R. Gertrag which started in 2008 has been supplying DCT gearboxes to BMW, Dodge, Mitsubishi, Mercedes-Benz and Ford, among the notable one. Bugatti Veyron’s DCT gearbox was made by Ricardo, while ZF makes it for cars from Jeep and Porsche.
Continuously Variable Transmission (CVT)
This is an automatic transmission system, which basically does not use any gears and is fundamentally different from any automatic transmission. Not well-accepted initially, by gearheads, CVT uses a length of chain-linked pulleys, wheels and cones, instead of gear cogs. This allows CVT to have a huge number of gear ratios which can change seamlessly according to the engine’s rpm.
The pulley-based system, the most common CVT type, among the many which are present. There is a belt with a V-cross section running between two pulleys, which are divided into two conical halves. The pulleys adjust themselves continuously to maintain the tension of the belt, as the length of the belt and the distance remains constant. The V-belt needs to really stiff in these cases. In case of vehicles with high torque/high-mass a steel belt is replaced by a chain. This is used by a coating of lubricant thick enough to prevent the pulley and chain from touching each other.
A development of traditional CVT is the hydrostatic CVT which has a variable displacement pump and hydraulic motor, which uses hydraulic pressure to rotate the outer shaft. This CVT system can handle and transfer more torque loads and reduce energy losses from the drivetrain.
The DAF 600 sedan was the first car to be built on a CVT transmission called Variomatic transmission. This was later used till the 1980s by Volvo. CVT has been principally used in passeneger cars like Ford Fiesta, Fiat Uno, Subaru WRX and Justy, Nissan Micra, Toyota Corolla and Nissan Altima.
The major advantage of a CVT are its low-cost manufacturing and outstanding efficiency figures. Due to their continuously variable gear ratios, CVT gearboxes always keep engines running constantly at healthy rpms. The major issues although are for hardcore enthusiasts, as CVTs take time to respond really strong braking and do not add any real feel to driving. Their is not any obvious change of engine sound or a rush of torque after gears are shifted, as their is no gear. So, this transmission really lacks a sense of involvement for the driver.
Shifting changes in the industry: How automatics are the “automatic” choices
As we already talked about, automatics had started becoming more popular with the turn of the century and have taken over the market in the last 15 years. A number of factors have come into play for automatics being the more preferred choice of the majority. The major cause of all this is the nature of the average American consumer and their demands. Americans are generally easy-going, casual people, who love everything convenient. Cars are no different.
Easy to drive
A major reason to choose any automatic is that you can keep driving your car while talking to someone over the phone or munching on a fresh turkey sub, without sparing too much though about your clutch or gears. Automatics might not be as “fun-to-drive” (something, which they are definitely now) but are definitely more comfortable and do not carry the hassles of a manual transmission, especially in bumper to bumper traffic.
Fuelefficiency and performance
In USA, compared to other countries of comparable economical status like Germany or Britain or even middle-income economies like India, the cost of gasoline is very less, nearly half or one-thirds the price. So the fuel-efficiency was never a huge factor in USA, despite early automated transmissions being much less efficient compared to manuals as well as not fast enough. But with growing technological advancements, like development of DCT and CVT transmissions, fuel efficiency has drastically improved and some have superceded manuals too. In terms of performance, manuals were much quicker with shifts as well as restoring torque than any automatic of the earlier era. But even that advantage has been rubbed off by some really good engineering and advancements in technology, automatic cars are faster, have quicker acceleration and a smoother ride today than ever before. The prevalence of technologies like cruise control, increasing number of wide roads suitable for high speed cruising have made automatics the choice of the day.
Ability to drive a manual
Learning to drive a manual car is an art and it takes time. You need to be absolutely in sync with your car’s engine revs, know the ideal RPMs to shift and drive efficiently and also effectively combine the use of brakes, clutch and gear while driving in busy traffic or on hilly inclines. And even that would be different for different cars, thus you need to time to understand the behavior of every car. But, why do you need to do that, when a modern day automatic can handle all that itself? Most Americans have no idea to drive a manual car, learn to drive in automatics, thus buy one. Companies do not produce manual cars because people hardly buy. In this date, it is only some of the muscle car manufacturers like Dodge, Chevrolet, Ford, Porsche and a few BMW’s that make some really fun-to-drive manual cars. Other than these, there are a few old-gen vintage cars, those driven by purists and the older generation, that still carry manual gearboxes.
Huge cost differences between manual and automatics might be a case in other countries, but its not so in USA, as there are hardly any manual cars. Although operational and repair costs are higher, as modern automatics are more complex as well as the parts are very much linked to each other and are not separately available. For example, you need to change the whole setup if your clutch plates are burnt due to excessive use in an automatic, while you just need to replace the clutch plate. But, years of research and millions of dollars are burnt by the companies to make automatic transmissions of the highest quality in terms of performance, efficiency and reliability, thus making modern automatics much more durable.
Feel and involvement while driving
You might get the fuel efficiency figures from a good CVT or AMT or some really aggressive shifts from a modern DCT gearbox, but the feel of pressing the clutch pedal and downshifting the gear to zoom past the car in front when you wish and the kind of involvement it provides, is something else, something no automatic can provide. That is what brings out the “fun-to-drive” factor in manuals. But today, these are things only for the enthusiasts, hardcore gearheads and old-gen purists. The average American is a commuter than a driver and uses the car for the sake of transportation, rather than a thing to enjoy and feel one with. So, for most of them. the ease of use and simplicity of driving matters rather than how good you feel while you hear the engine rev to screaming point as you shift a gear down.
So, despite the concerns of a small section of enthusiasts and hardcore drivers of the muscle car community, automatics are more usable, practical and with better performance have won the hearts of people of USA. Also noteworthy, is that manual transmission has reached its pinnacle of advancement while for computer and actuator controlled automated systems, still a lot remains to be accomplished. All in all, automatics are the ones to choose as manuals fade away to obscurity.