Engineering New Transmissions

by Ann Job, a writer for T&A Ink.

Automakers are re-engineering transmissions to boost performance and fuel economy, and reduce emission. Even with all the new transmission developments going on, automakers today don't make the transmission a prominent element in advertising as it was in this Ford ad from 1951.

More shift-it-yourself "manumatic" automatic transmissions are offered in vehicles today. This is the gearshift lever for the SporTronic in Mitsubishi's Endeavor sport-utility vehicle.

Ford begins offering a continuously variable transmission (CVT) in 2004. CVTs operate via pulleys or bands that allow an infinite variability between highest and lowest gears with no discrete steps or shifts.

Most car shoppers aren't clamoring for them, but newfangled transmissions—with more gears, more electronic controls and new features—are popping up in showrooms in ever-increasing numbers.

They're going into every kind of vehicle, from lower-priced, entry-level cars like the Saturn Ion with a 5-speed automatic transmission to Nissan's first full-size pickup, the Titan, with an automatic that lets truckers shift it themselves without depressing a clutch pedal. Already, BMW's flagship sedan, the 7-Series, is sold with a 6-speed automatic.

Automaker officials say that after decades of working to improve fuel economy and efficiency as well as performance of engines, they're now turning their attention to transmissions and seeking improved fuel economy, efficiency and performance there, too.

In fact, to hear transmission engineers tell it, the auto industry around the world is in the midst of an unusually busy time for transmission development. Activity "is definitely on the upswing, and there's a lot of focus now on new transmission technology," said Veronica L. Mirabitur-Sptiz, chief engineer of General Motors Corp.'s family of 6-speed, rear-wheel-drive transmissions.

Craig Renneker, executive engineer for Ford's automatic transmission operation, agreed, saying in his 16 years in the transmission arena, "I've never, never seen the technologies being developed at this rate."

Basically, the major areas of transmission changes involve adding more gears, the rising use of continuously variable transmissions (CVTs) and the addition of new features such as shift-yourself manumatic automatics and steering wheel-mounted shift controls.

Why Now?

Just 10 years ago, automatic transmissions in cars, vans and trucks "were mainly 4 speeds," said Christian Bock, development manager for automatic transmissions at BMW AG in Germany.

He, Renneker and Mirabitur-Spitz attribute the new transmission activity to the fact that auto engineers' experience with electronics and electronic controls has matured and now is spreading beyond engine management systems and airbag systems.

The durability and sophistication of automotive electronics also has advanced to the point where automakers see great potential in engine control modules and transmission electronics working together.

Bock admitted that generally, car shoppers aren't asking for the new transmissions. "Basically, the customer is more interested in the car, and he just wants an automatic (for example), he doesn't want to think too much about the technology," he said.

Automakers also are juggling regulatory demands for better fuel economy and continued emission concerns worldwide. Indeed, competition to stay abreast of transmission trends is so keen that traditional domestic competitors GM and Ford have agreed to team up to develop a new automatic transmission with six forward gears, rather than the conventional four or even five.

This effort combined with other Ford development work means "fifty percent of our transmission lineup in North America will be all new by 2008," said Phil Yuhasz, chief engineer for automatic transmissions.

More Gears

If the last time you shopped for a new car was 1994, when the low-priced Dodge Neon debuted with a 3-speed automatic gearbox, you are in for a surprise.

Today, the Neon has an automatic with four forward gears. The same holds true for a myriad of other low-priced cars, including the lowest-priced small car in America, the 2003 Kia Rio.

When Saturn's Ion small car bowed in fall 2003, its automatic was fitted with five forward gears. Meantime, when BMW redesigned its 7-Series for the 2002 model year, it replaced the former 5-speed automatic with a six speed, and Audi's TT was fitted with a 6-speed automatic for the first time in the 2003 model year.

Recall that a transmission manages how engine power is delivered to a vehicle's wheels. Auto engineers say a greater gear spread or wider gear ratio span provided by a 6-speed automatic is advantageous because engineers can increase the gear ratio of the first gear, raising engine speed or rpm, to improve a vehicle's launch. This makes drivers feel they're behind the wheel of a more responsive, spirited vehicle.

Then, engineers can reduce the top gear ratio in the 6 speed, thereby lowering engine speed or rpm during highway driving and improving fuel economy.

"You can't do that with a 3-speed or a 4-speed where there's a narrow gear ratio span," Renneker said. "In that case, you have to choose one (priority) or the other (either the spirited driving or fuel economy)."

He added the change is substantial. For example, a 4-speed automatic may have a ratio span of 4:1, but adding more gears can move that to 6:1, for a 50 percent increase.

BMW made other changes beyond adding a sixth gear in its automatic. Bock said the electronics for the new transmission are put into the gearbox because, among other things, it helps give smoother, better quality shifts that drivers notice.

All Sorts of Gears

CVTs have been around for years -- remember the Subaru Justy from the late 1980s?

Only recently have designs and electronics made CVTs more advanced.

As a result, more CVTs are being offered on an increasing number of vehicles. For example, Saturn's Vue sport utility is offered with a CVT, while Audi has several cars, including the A4 and A6 that use Audi's multitronic CVT.

CVTs operate like automatics in that drivers don't have to manually shift gears. In fact, some drivers don't notice that they're using a non-traditional transmission.

CVTs differ because they don't have a set number of gears. Rather, they operate via pulleys or bands that allow an infinite variability between highest and lowest gears with no discrete steps or shifts as there are in typical automatics.

This helps a vehicle's engine to operate at its most efficient speed more frequently than in a conventional vehicle, thereby improving fuel economy.

Ford plans a new family of Ecotronic CVTs on U.S. vehicles starting in 2004. They include the Ford Freestyle crossover vehicle and the Five Hundred sedan.

"While this fundamental technology is not new, we do expect to lead the industry in the volume of CVT-equipped vehicles," Renneker said. "Our design is more advanced than previous CVT designs."

New Transmission Features

A few years back, only luxury and sports cars had automatic transmissions that let drivers shift forward gears, sans clutch pedal, for sporty performance.

Today, however, the feature—made possible by electronic transmission controls—is available in a wide range of vehicles. For example, drivers can manually shift the 4-speed automatic in Kia's Optima sedan without using a clutch pedal. Starting with the 2003 model, drivers of the Range Rover have a Streptronic transmission for the first time. Mitsubishi's Outlander crossover vehicle as well as Endeavor SUV have a 4-speed automatic with a similar system called Sportronic. Transmission electronics allow other innovations, too.

BMW's M3 coupe and convertible offer a Sequential Manual Gearbox (SMG) with steering wheel-mounted shift buttons, like those in race cars. The system goes beyond the location of the buttons, though. BMW boasts SMG's electrohydraulic mechanism that does the actual shifting and clutch actuation makes for faster gear shifts.

Meantime, Toyota's current 4Runner with first-ever V8 includes a 5-speed automatic that changes gear-shift patterns according to driving conditions and what its artificial intelligence unit deducts is "driver intent." Hold on to your gearshift levers. More innovations are on the way!

Examples of the latest transmission developments.

More Gears

The Saturn Ion sedan has a 5-speed automatic transmission. The Ion replaced the 2002 Saturn S-Series, which had a 4-speed automatic. Starting in 2003, the Honda Accord offered a 6-speed manual transmission for the first time. Mated to a V6, the model is the "ultimate sport Accord," according to Honda. BMW's redesigned and re-engineered 7-Series bowed in the 2002 model year with standard 6-speed automatic transmission. Its predecessor had a 5-speed automatic. The 2004 Lexus RX 330 pairs its revised V6 with a new, 5-speed automatic transmission. The 330 replaced the 2003 RX 300, which had a 4-speed automatic. In 2003, Ford replaces its 4-speed automatic transmission with a new, 5 speed on F-Series Super Duty pickups and the Excursion sport utility.

Shift-It-Yourself Automatics

The 2003 Chrysler PT Cruiser GT was the first PT with available AutoStick. Mazda's 6 sedan with V6 offers a 5-speed automatic with manual shift mode. It replaced the Mazda 626 sedan that had a 4-speed automatic without manual shift mode. Nissan's 2004 Titan will be the first full-size, passenger pickup truck with manual shift mode on its automatic transmission. The transmission also has 5 gears.

Continuously Variable Transmissions (CVTs) A CVT was among the transmission offerings when the 2002 Saturn Vue sport utility debuted. It was the first Saturn with a CVT. Ford plans to offer CVTs on its Freestyle family vehicle and Five Hundred sedan in 2004.

Steering Wheel-Mounted Shift Controls

The 2003 Mercedes-Benz SL55 AMG has a 5-speed automatic transmission with SpeedShift buttons on the steering wheel that make gear changes quicker.

BMW's 2002 M3 bowed with an "automated" 6-speed manual with Sequential Manual Gearbox that offers faster shifting. Porsche's sport utility vehicle, the 2004 Cayenne, has a new, 6-speed automatic transmission with Tiptronic S that allows gear shifting via thumb switches on the steering wheel.

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