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BMW M6

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Seven-speed SMG transmission conveying M Power to the road

BMW's seven-speed SMG transmission will be the only one offered in the new BMW M6. This gearbox from BMW M is indeed the world's only sequential transmission with seven gears and Drivelogic. With qualities even greater than on a six-speed SMG gearbox, this transmission allows manual selection of gears with extremely short gearshift times as well as comfortable cruising qualities thanks to the automatic gear selection function. And at the same time the additional gear keeps the increments between engine speed and torque even smaller, ensuring an absolutely smooth process of one gear "flowing" into the other.

The driver shifts gears in the SMG transmission either from the selector lever or via paddles in the steering wheel. Compared with the conventional SMG transmission, the new generation of SMG technology performs the entire gearshift process 20 per cent faster, gears merging directly into one another.

As a result, any interruption of the flow of power inevitable when shifting gears now becomes hardly perceptible. The BMW M6 accelerates virtually without the slightest jolt or interruption from a standstill all the way to top speed.

Drivelogic: The driver determines how SMG shifts gears

Featuring its special Drivelogic function, SMG on the BMW M6 offers the driver a total of 11 gearshift options allowing him to individually adjust the gearshift characteristics of the SMG transmission to his personal style of motoring.

Six of these driving programs come in the sequential manual function (S-mode), ranging from smooth but dynamic all the way to race track crisp. Driving in the S-mode, the driver shifts gears manually. But thanks to the launch control function SMG Drivelogic shifts gears automatically shortly before the engine reaches its maximum speed, ensuring an optimum gearshift process with optimum spin control all the way to the top speed of the BMW M6.

In the automatic shift mode (Drive = D-mode), the transmission shifts the seven gears automatically as a function of the driving program currently in use, the driving situation, road speed, and the position of the gas pedal.

SMG for even greater safety and motoring comfort

Seven-speed SMG supports the driver not only in achieving and enjoying the highest standard of performance comparable to genuine motorsport, but it also comes with many safety features opening up the clutch within fractions of a second in a critical situation - for example when shifting down on a slippery surface - in order to keep the car stable and free of excessive engine forces acting on the drive wheels. A further special function is hill detection, which adjusts the gearshift points on uphill and downhill grades. Driving uphill, this avoids the common phenomenon of the gears constantly shifting up and down ("pendulum gearshift"); driving downhill the hill detection mode holds lower gears in mesh longer than usual in order to capitalize on the engine's braking effect.

Last but not least, SMG also enhances the particular sound effect of the V10 power unit: To quote a specialist commenting on this special sound, that "brief, roaring rumble" is simply fantastic when the electronic engine control unit "blips" the throttle between gears when shifting down.

Maximum driving pleasure

Interaction of the V10 power unit and seven-speed SMG gives the driver of the BMW M6 Coupe driving pleasure of the highest caliber: Acceleration from 0-100 km/h (62 mph) comes in 4.6 seconds and the M6 reaches 200 km/h or 124 mph in just about 14 seconds. Then, at a speed of 250 km/h or 155 mph, the electronic speed governor ends the car's irresistible surge of power, while the speedometer gives you an idea where the engine would take you without such electronic speed control: the speedometer goes all the way to 330 km/h or 205 mph.

 

 

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The Seven-Speed SMG Gearbox: Shifting Gears like in Formula 1

To provide perfect results, the high-speed engine concept must be combined with an appropriate transmission. This is the only way to convert the power coming from the engine into optimum momentum on the road by means of the right - short - overall transmission ratio.

BMW's Sequential M Gearbox (SMG) with seven speeds is well suited to conveying the power of the V10 to the drive wheels. BMW M is the first manufacturer to offer such a sequential gearbox with seven gears and Drivelogic, which provides both a manual gearshift with extremely fast shift times as well as an automatic transmission function for cruising comfortably in style.

In technical terms, the gearbox is conceived for torque of up to 405 lb-ft and engine speeds of up to 8,500 rpm. In other words, it offers adequate reserves for consistent reliability throughout the car's complete running life, with additional back-up being provided by a separate oil cooler for the high-performance transmission.

BMW M6 SMG Transmission
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Even smaller gear increments than with BMW's six-speed gearbox

Seven gears keep the gaps between engine speeds and torque levels when shifting gears even smaller than with a six-speed gearbox. And since the power actually conveyed to the wheels depends on high engine speeds, such smaller increments are the best guarantee for truly dynamic acceleration.

SMG transmission for the pure joy of shifting gears

The seven-speed SMG transmission offers all the benefits of the sequential gearbox concept: The driver is able to shift gears either via the selector lever in the center console or from paddles on the steering wheel, without having to press a clutch pedal. Instead, the driver can even keep his foot on the accelerator while shifting gears. And unlike automatic transmission, the Sequential SMG Gearbox does not need a torque converter taking up energy and reducing the car's performance.
The SMG transmission shifts all gears electrohydraulically with all control units operating by wire, that is, without any mechanical connections. Both the SMG hydraulic unit and the gearshift actuators are integrated in the transmission housing. Whenever the driver wishes to shift gears, the control unit activates the appropriate solenoid valves within thousandths of a second, setting the hydraulic system as required. Now the hydraulic fluid under a high level of system pressure of up to 90 bar is able to flow into the clutch master cylinder within fractions of a second, opening the clutch in the process. This, in turn, serves to activate four hydraulic cylinders in the gearshift actuator controlled by solenoid valves in the hydraulic unit. The four hydraulic cylinders then serve ultimately to shift the gears by way of four separate gearshift rods. And when down-shifting, the engine automatically "blips" the throttle between gears.

New SMG 20 per cent faster than before

The third generation of SMG transmission now featured in the BMW M6 speeds up the gearshift process by no less than 20 per cent. Gears are shifted in a "flowing" process much faster than even an experienced driver would be able to. The interruption of power when shifting gears is barely perceptible. The BMW M6 therefore accelerates from standstill to top speed in a virtually ongoing surge of power and torque, as if there were no interruption whatsoever. SMG offers an almost incomparable Formula1 experience.

A further advantage of the SMG gearshift is the increase in traffic safety:
With gears shifting at the same persistent speed and in the same precise, absolutely reproducible process, the driver no longer has to concentrate on the gearshift as such. The result is an even more precise, safer and relaxed style of motoring.

Drivelogic: The driver chooses his particular SMG gearshift

The Drivelogic function gives the driver a total of 11 gearshift options individually adjusting the SMG gearshift to the driver's particular style of motoring. The first and most significant distinction between these driving programs is the pre-determined gearshift speed: The higher the program, the engine speed and load, the quicker the gearshift. Six of these 11 gearshift options come with the sequential manual gearshift function (S-mode) ranging from smooth and dynamic all the way to high-performance. And in the S-mode the driver always shifts gears by hand.

Launch control: Accelerating to top speed with full power all the way

The launch control function in the S-mode supplements the purist and sporting M6 driving program, enabling the less experienced driver to accelerate perfectly from a standstill, using all of the car's power and acceleration in the process. In this case you switch off DSC in advance.

Launch control serves to relieve the driver of the usual chore of shifting gears himself. So with the car at a standstill, all the driver has to do is push forward the selector lever and keep it there. Now, pressing the gas pedal, he automatically sets the engine to its optimum start-off speed. Then letting go of the selector lever, the driver enables his M6 to accelerate with ideal wheel spin management, provided the driver's foot remains fully on the gas pedal. There is subsequently no need to shift gears all the way to the car's top speed, SMG with Drivelogic shifting gears automatically in each case shortly before maximum engine speed and thus moving up smoothly from first to seventh gear.

As in the S and D modes, a display in the cockpit activated during launch control informs the driver of the gear currently engaged.

Automatic transmission straight from the race track

Five of the 11 Drivelogic programs are available in the so-called automated
D-mode in which the transmission shifts the 7 gears automatically. This it does as a function of the driving program currently in use, the respective situation on the road, the speed of the car, and the position of the gas pedal. Driving program D1, for example, sets off in second gear and ensures particularly sensitive operation of the clutch for smooth motoring and acceleration on, say, snowbound roads or quite generally in winter. The driver is able to influence this automatic gearshift by slowly taking back the gas pedal to shift up in the D-mode, too. Conversely, he is able to shift back quickly by pressing the gas pedal all the way down. Both in the S- and D-mode, the transmission automatically shifts back to first gear as soon as the car comes to a standstill. Then, to set off again, all the driver has to do is press the gas pedal.

Special functions for extra safety and comfort

The seven-speed SMG transmission in the BMW M6 supports the driver not only in terms of optimum motorsport performance, but also by way of many safety features. In a critical situation, for example when shifting back on a slippery road, SMG opens up the clutch within fractions of a second to prevent high engine forces being transmitted to the drive wheels and causing them to lose traction.

An intelligent transmission on grades

Hill Detection modifies the gearshift points on uphill and downhill grades: Driving uphill, this avoids a constant shift of gears up and down; driving downhill the function keeps lower gears in mesh for a longer period in order to capitalize on the engine's braking effect. And in the D-mode the Hill Detection function sets the gear chosen to the actual grade encountered at any given point in time.

These functions are only possible thanks to the close link between the SMG control unit and the engine management system communicating directly with one another. This communication is provided by a high-performance CAN data bus connecting the MS S65 engine control unit with the SMG control unit networked to 12 redundant SMG sensors. The SMG control unit therefore receives all relevant data from the MS S65 "brain" on the current position of the gas pedal, wheel and engine speed, temperatures, the steering angle, and Key Memory settings. And last but not least, SMG and DSC also communicate directly with one another.

 

links

 Links

More 6 Series models:

Wallpaper-sized pictures of the BMW M6.

What makes an M6? How about a V-10 engine pumping over 500 horses!

BMW-Williams F1 racing homepage.

The chassis and suspension allows this great car to corner and stop as well as it does.

The exterior design is understated but powerful.

The interior of the M6 is quite luxurious for a muscular car.

The M6 specifications has "the tale of the tape".

Looking for a powerful sedan? The BMW M5 shares the V-10 engine and more with the M6.

 


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