That whirring sound you hear is Henry Ford and Louis Chevrolet revving up in their graves. Why? Because Chevy and Ford are collaborating on automatic-transmission design and development. This has been going on for more than a decade, with the first fruits of this cooperation appearing as the six-speed automatic transmissions currently in wide use throughout Ford and General Motors.
Based on that trial’s success, the Detroit rivals agreed to an additional program in 2013 covering new nine- and 10-speed automatics. Ford already is producing the jointly developed 10-speed for F-series trucks; the Mustang is expected to get it soon, too. Chevrolet’s Camaro ZL1 arrives soon with GM’s version, followed by eight additional 2018 models. The nine-speed is for front-drive applications. GM Powertrain engineers led the design of that gearbox for both companies, and Chevrolet has just introduced the Hydra-Matic 9T50 for the 2017 Cruze diesel, the 2017 Malibu, and the all-new 2018 Equinox, with additional applications to follow.
Competitors enter these sorts of agreements from time to time because designing new transmissions is a labor- and resource-intensive process, and few customers know or care where their transmissions come from. In spending the same time and investment dollars required to engineer one transmission, Ford and GM reaped two new state-of-the-art designs. The same parts used by both companies are identified with different Ford and GM part numbers. Even though the hardware is common, each company writes its own software code to achieve distinctive operating characteristics.
Every maker is adding gear ratios to improve drivability and fuel efficiency. A sufficiently low gear is needed to launch the vehicle smartly from a stoplight. Extra gears facilitate snappy acceleration through the full speed range. Then, when the driver lifts off to cruise the interstate, an overdrive gear reduces rpm to hold the engine at a quiet and efficient operating point. Narrowing the space between ratios with more gears minimizes commotion. The new nine-speed has an overall ratio spread of 7.6:1 versus the outgoing six-speed’s 6.0:1.
The 9-speed automatic will also be found in the redesigned 2018 Chevrolet Equinox SUV.
Computer-aided design and a few clever touches helped GM Powertrain engineers pack five planetary gearsets, four stationary clutches, and three rotating clutches into the existing six-speed’s space. The new transmission weighs an additional 22 pounds, a fair price to pay for the expected 2 percent gain in fuel efficiency.
More than 60 patents filed by GM cover innovations such as replacing the two clutches previously used to control reverse and first gears with a single, more compact device called a selectable one-way clutch. Computer-controlled solenoids manage all shifting functions. A large hydraulic pressure accumulator supports the essential engine stop/start function. The new elliptical-cross-section torque converter is more compact and provides three operating modes: full slippage, partial slippage, and full lockup. Gears are skipped in certain accelerating and coasting conditions to improve smoothness. Automatic downshifts provide engine braking on downgrades.
In manual mode (what GM calls range select), the driver can hold a gear with engine rpm at or near the redline. Final-drive ratios ranging between 2.89:1 and 3.81:1 are available, and this nine-speed is engineered for four-cylinder, V-6, front-, and all-wheel-drive applications.
The Hydra-Matic 9T50 will be available in 10 models throughout GM by the end of 2017. While Ford hasn’t yet revealed its plans to implement the nine-speed automatic, rest assured that it’s not about to lag behind in the ratio race.
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