DETROIT -- When the 2018 redesigned and re-engineered Honda Odyssey minivan arrives this spring, two models will be available with the industry’s first 10-speed automatic transmission in a front-wheel-drive vehicle.
The lightweight, compact gearbox, on display this week at WCX17, SAE International’s annual conference, is expected to propel Honda to the front of the pack in fuel economy in the segment, said Tom Sladek, Honda’s powertrain development leader.
During a presentation Tuesday at the conference, Sladek explained how, during six years of development, Honda engineers in Japan reduced the size of the 10-speed so it fits between the frame rails of the Odyssey -- no easy feat of engineering. Automatic transmissions tend to take up a lot of space under the hood, and adding more gears complicates matters further.
Sladek explained that engineers focused on two key elements of the transmission’s internal parts -- the clutches and the output gear -- to help create the compact transmission.
“First, we were able to take the typical wet clutch and one-way clutch and put them in one component. And that saved about 25mm of packaging space,” Sladek said. “The other is a combination internal/external gear -- which internally we call gear-on-gear -- essentially what it is the output gear, and internal to that we have a ring gear from one of the planetary sets. That alone is able to save 45 mm of packaging space.”
A cutaway on display at SAE attracted engineers from other companies, including three from General Motors. “It’s extremely compact,” said Dave Varda, a senior project engineer at GM. Chi Teck Lee, a GM transmission specialist, wondered if the shifting would feel busy.
Sladek revealed some performance figures of the transmission, such as when driving at 70 mph, the engine will run at 1560 rpm, which will help boost fuel economy and reduce engine noise. He also said the transmission is capable of skipping gears on downshifts.
For instance, the transmission could shift from ninth gear to fifth gear on a hard acceleration, such as when merging on the highway. The number of gears it skips depends on driver input, he said.
Honda will continue to offer a nine-speed automatic transmission from ZF in the Odyssey on lower trim levels.
Several other automakers have launched 10-speed automatic transmissions, but those are used in rear-wheel drive cars and trucks. GM, Ford, Land Rover, Acura and others have nine-speed automatics available in front-wheel drive cars.