01-21-2006, 11:54 PM
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Join Date: Mar 2005
Location: Sugarland (Houston) Texas
Posts: 774
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No, SMG from what I've read is one clutch.
http://forums.e60.net/index.php?act=...e=post&id=6406
http://www.bmwcca.org/Roundel/2004/10/Article_1.shtml
Quote:
The new Sequential Manual Gearbox (SMG) III transmission matches the refinement of the engine: a seven-speed manual gearbox with Drivelogic functions developed and built by Getrag exclusively for the M5. It is not an adaptation of a regular transmission with SGM add-ons, it is a whole new concept, including the multidisc clutch activated by a hydraulic transmission control system whose actuators and control unit are built into the gearbox housing. As hydraulic fluid (pressurized to 1,300 psi) moves a piston in the clutch master cylinder, sophisticated sensors on both sides of the piston monitor its travel. The computer actually starts pulling one gear out of engagement at the same time it begins to push another one in; this procedure allows the new SMG III to shift 20% faster than its SMG II predecessor. Those who found previous SMG boxes "too slow" should have no worries; shifting speed has been reduced to 65 milliseconds. ("We could cut another twenty," says one transmission engineer, "but it would seriously increase wear on the synchros.") The transmission, designed for a 550-Nm torque limit, can easily handle 8,500 rpm.
The use of seven speeds is not to keep the engine in a narrow torque band, but rather to allow more frequent shifts with less of a jump between gears----to eliminate the jerkiness of a normal off-the-gas, inwith- the-clutch, out-with-the-clutch-andgo- again shifting procedure. Sixth gear is direct at 1:1, and seventh is an overdrive.
To increase the shifting speed, as well as strengthen the gearbox, the gears are mounted on two shafts, with the lowest gears mounted closest to the bearing housings. The gear arrangement is ideal for computerized "overlap" shifting, but it completely eliminates any possibility of using the seven-speed as a "left-leg" manual; the shifting gates in the console would have no logical sequence to follow. BMW, of course, sees the SMG gearbox as a technical advance, and is somewhat perplexed at the American demand for a footoperated clutch. (In conversations with BMW AG product director Dr. Burkhard Göschel, Roundel editor Carlson suggested that perhaps Americans see the SMG as being too much of an automatic transmission. "Maybe," sighed Göschel, "we never should have given them the ‘automatic' options.")
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Of the PDF, start on page 8 and you can see the tranny. If you look through the details, it doesn't mention a second clutch anywhere nor anything to work the second clutch. That's what I've inferred from those links.
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