All Corvette models (base and Z06) customers will have the option to choose a manual transmission or a 8 speed transmission. This GM developed 8AT (code name: 8L90) is different than the 8AT that is currently used in the Cadillac CTS 3.6 (which is sourced from Aisin).
The 8L90 transmission used in Corvette has different packaging requirements than other traditional 8AT units. Unlike other rear wheel drive cars, the Corvette’s transmission is installed in the rear side of the car, after the occupant cabin, which is suitable to optimize the front/rear weight distribution of the sports car. Traditional 8AT units which are installed in the engine bay (which is a typical layout for most of the RWD cars), cannot fit Corvette’s layout schema. Therefore a dedicated design is required.
Key points of this GM transmission:
– Has 4 planetary gear sets and 5 shifting elements (which is the same as the ZF 8HP);
– Maximum torque handling: 738 lb-ft;
– 7.7 lb lighter than the 6sp transmission (6L80) used in the current Corvette;
– Transmission case is made of aluminum, clutch piston housing and control system cover plate are made with magnesium;
– Build in Toledo, OH;
– Upshift can be up to 8/100 second quicker than PDK transmission used in the current Porsche 911.
Since GM claims superior performance than the Porsche PDK, here is some more info regarding the Porsche transmission for your comparison: the common 911 PDK shifting speed is around 150ms, 911 GT3’s PDK-S can do it within 100ms. If the 8L90 can beat 911 GT3 shifting speed by 8/100 second then it means it can do the upshift within 20ms, sounds like a very revolutionary performance.
Below is the GM press release:
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2015 Corvette Stingray to Offer Eight-Speed Automatic
Paddle-shift gearbox rivals dual-clutch performance, enhances efficiency
DETROIT – An eight-speed paddle-shift automatic transmission will be offered in the Chevrolet Corvette Stingray for 2015, enhancing the performance and efficiency of the 2014 North American Car of the Year. Designed and built by GM, the new transmission delivers world-class shift times that rival the best dual-clutch designs.
The all-new, GM-designed 8L90 eight-speed is expected to contribute up to 5-percent greater efficiency, when compared to the previous six-speed automatic. EPA fuel economy test results are pending and will be announced later. It also makes the Corvette Stingray one of the few sports cars to offer the choice of a conventional manual transmission or an eight-speed automatic.
“Corvette Stingray’s new eight-speed automatic delivers the comfort and drivability of a true automatic transmission, as well as lightning-fast shifts and the manual control that enhance the performance-driving experience,” said Bill Goodrich, assistant chief engineer for eight-speed automatic transmissions. “It was designed to enhance the Stingray’s driving experience, with performance on par with dual-clutch designs, but without sacrificing refinement.”
The available 8L90 transmission is based on the same eight-speed automatic that will be offered on the supercharged 2015 Corvette Z06, but with unique clutch and torque converter specifications matched to the torque capacity of the Stingray’s LT1 6.2L naturally aspirated engine.
For performance driving, the transmission offers full manual control via steering wheel paddles. A new transmission-control system and unique algorithms deliver shift performance that rivals the dual-clutch/semi-automatic transmissions found in many supercars – but with the smoothness and refinement that comes with a conventional automatic fitted with a torque converter.
The transmission controller analyzes and executes commands 160 times per second. Wide-open throttle upshifts are executed up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911.
Smaller steps between gears, compared to the previous six-speed automatic, keep the engine within the sweet spot of the rpm band, making the most of its horsepower and torque to optimize performance and efficiency.
With four gearsets and five clutches, creative packaging enables the new eight-speed automatic to fit the same space as the previous six-speed automatic. Extensive use of aluminum and magnesium make it more than eight pounds, or 4 kg, lighter than the six-speed. Design features that reduce friction contribute to the expected 5-percent greater efficiency.
The 8L90 is built at GM’s Toledo, Ohio, transmission facility.
Founded in 1911 in Detroit, Chevrolet is now one of the world’s largest car brands, doing business in more than 140 countries and selling more than 4.9 million cars and trucks a year. Chevrolet provides customers with fuel-efficient vehicles that feature spirited performance, expressive design, and high quality. More information on Chevrolet models can be found at www.chevrolet.com.
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