Filed under: BMW
BMW has also a double-clutch transmission
Although installed in a car which merits no mention here (the last iteration of the M3, with a V8 engine by the way), BMW has used a new double-clutch transmission with seven forward gears. As with other double-clutch transmissions, one of the clutches drives the odd gears (Rear, 1, 3, 5, 7), while the second manages even ones (2, 4, 6). Both clutches, in pure racing fashion, are oil-cooled with a specific dedicated oil radiator.
Then the gearbox gets some additional software and hardware called Drivelogic, which allows the driver to use up to eleven driving program choices, including a manual mode.
With all this, BMW claims that not only the car performance gets noticeably improved, but also fuel consumption and CO2 emissions.
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[Source: BMW]
Reader Comments (Page 1 of 1)
amg 5:42PM (1/18/2008)
I love the idea of a DSG, and I would love to see them on more models. Maybe I would miss the clutch, but I bet I wouldn't. They would be so much more efficient than standard automatics, and they would be great for people like me who prefer to shift ourselves and like the idea that the engine doesn't have to slop around oil to get the tires to move.
7 gears does beg the question: how many forward gears are we going to have before it makes more sense to go to CVT. CVT is the only type of automatic I would drive (again, I like the idea of the direct connection, even if through a belt), and I have driven one, and it's a bit weird at first. But would shifting 8 or 9 gears be even more weird?
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MikeW 7:57PM (1/20/2008)
What is the widest ratio CVT for cars?
Nissan's [JATCO] CVT in the Altima V6 is 5.4:1, where normal 6 speed automatics are 6:1 (say a '05 Mazda6 V6) Both have torque converters.
The close ratio 6 speed auto in the Camry is only 5.4:1, narrower than the previous dual range 4 speed automatic, 5.6:1 (underdrive1,2,3,direct drive3,4)
The CVT in the Altima 2.5 is 6:1, and so is the 6 speed automatic in the Malibu (6t40)
The ZF 6 speed auto (first gen. came out in the BMW 7 series) was 6:1, same gears for 2nd gen.
The MB 7g-tronic is only 6:1 ratio spread.
The 6 speed automatic in the LS430 (previous model) was 6.6:1. and that was improved from the 4.5:1 of the 5 speed auto LS430.
The '8' speed auto (it is a compounded 4 speed auto) in the current LS460 is only 6.7:1
The new ZF 8 speed auto is only 7:1
So the Audi Multitronic is the widest CVT, and that started at 6:1, and is only increased to 6.73:1.
and the ZF 7 speed auto (which no one purchased, and wasn't produced, had a 7.28:1 because the torque converter was ditched in favor of a wet clutch)
So if you can make a CVT with a 7.5:1 ratio spread...
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