Kia announced its all-new eight-speed automatic transmission, designed for front-drive, transverse-engine applications, when it debuted the 2017 Cadenza sedan. However, the transmission was only mentioned in passing—the focus, of course, was on the Cadenza’s overall newness—but we now know more as Kia has offered a deeper look at the eight-speed.
Set to replace the old Cadenza’s six-speed first, the eight-speed is entirely Kia’s. That tidbit is worth a mention given that most manufacturers are turning to eight-plus-speed transmissions designed by ZF, Aisin, and the like. In any case—pun intended—the eight-speed gearbox occupies roughly the same space as the six-speed it replaces, and it’s also 7.7 pounds lighter.
Per Kia, the new transmission has an additional clutch and a fourth planetary gearset (bringing it in line with the number of gearsets used by the ubiquitous ZF nine-speed auto), and benefits from a 34-percent-broader ratio spread between first and top gear as compared with the six-speed. It also uses what Kia describes as the smallest oil pump in its production-transmission class to reduce parasitic losses on the engine, improving fuel economy. A reduced number of control valves and a direct control valve body with solenoid control over the clutches are claimed to return quicker shifts and a “more direct mechanical link to the engine,” which we assume means a more positive feel to the engine–transmission combination. Ditto the eight-speed’s torque converter, which uses a multi-disc design (the six-speed had a single disc) and features an expanded lock-up range, also for a more direct feel and improved fuel economy.
It isn’t yet clear whether the transmission can support a driveshaft to a rear axle for all-wheel-drive applications, but given how Kia says the eight-speed will supplant its old six-speed in “a number of mid-sized and larger front-wheel drive models,” one would expect so.
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