• Developed in-house for front-wheel drive models.
• Lighter weight and similar dimensions as conventional six-speed auto
• 143 new patents filed during its development.
Kia Motors has revealed details of the FWD-8AT – its new eight-speed automatic transmission – engineered for use in front-wheel drive vehicles.
The new transmission has been developed in-house by the Korean automaker, engineered to offer a high level of mechanical efficiency and smooth gear transference. Crucially, as is the norm these days, the new 8AT is the same size as a conventional six-speed automatic transmission, but weighs 3.5kg less.
Kia’s engineers already have experience of developing eight-speed transmissions for rear-wheel drive vehicles, mounting the transmission longitudinally and sending power to the rear axle. However, incorporating the same number of gears into a front-wheel drive car is incredibly challenging, due to packaging constraints and the need to mount the transmission transversely, competing for under-bonnet space with the engine, suspension and auxiliary components.
In development since 2012, the development program for the breakthrough transmission led Kia to patent 143 new technologies to ensure a high level of performance and efficiency in a compact structure. This new transmission enables smooth acceleration from standstill, as well as greater fuel efficiency, improved NVH (noise, vibration and harshness) characteristics and more decisive acceleration at high speeds than an automatic transmission with fewer gears.
To improve the 8AT’s fuel economy, the automaker’s engineers significantly reduced the size of the oil pump (the main source of power loss in an automatic transmission) and simplified the structure of the valve body. Boasting the smallest oil pump of any production transmission in its class, the 8AT is able to use hydraulic oil more efficiently, distributing it evenly throughout the unit at all times.
Development teams also incorporated a direct control valve body to allow solenoid control of the clutch directly, rather than via several control valves. This enabled Kia to reduce the number of control valves from 20 to 12, resulting in quicker gear shifts, a more direct mechanical link to the engine and improved packaging.
Incorporating an additional clutch and gear over the existing 6AT, the ratio between the top gear and the lowest gear in the new transmission has been increased by 34 per cent over the 6AT, resulting in greater fuel economy and improved NVH in higher gears and faster acceleration and climbing performance in low gears.