New M DCT dual clutch transmission by BMW

[Alwing]

You can't conclude much from the names. Similarities don't automatically mean they actually have something in common (eg. Steptronic, Autotronic). I'm not even sure what's the official name for BMW's new transmission. Some sources say "M DKG" which is dual-clutch transmission in German, others "M DCT" (DCT = Dual-Clutch Transmission). Maybe EnI or Scott can tell us which company developed this transmission. It may have been Getrag or ZF or perhaps even some other transmission specialist (LuK, BorgWarner etc.)
I think we will have to wait until we now for sure if the AMG MCT is indeed a DCT and if it's MB's own transmission or made by an outside company.

I didn't conclude anything, I was just pointing out some similarities and the possibilities whether they could be related.
And concerning BMW's new DCT transmission, according to the sources it's build by Getrag unless they have been misinformed.
I only wasn't sure about the Mercedes MCT supplier whether it was Getrag as well or ZF. Anyway some sources:

BMW to offer new M3 with DSG-like seven-speed gearbox
BMW to introduce dual-clutch gearbox
http://www.caradvice.com.au/2966/2008-bmw-m3-m-dct-gearbox/
M3, meet DSG: BMW M3 gets 7-speed double clutch 'box - Autoblog

 

[bmer]

I didn't conclude anything, I was just pointing out some similarities and the possibilities whether they could be related.
And concerning BMW's new DCT transmission, according to the sources it's build by Getrag unless they have been misinformed.
I only wasn't sure about the Mercedes MCT supplier whether it was Getrag as well or ZF. Anyway some sources:

BMW to offer new M3 with DSG-like seven-speed gearbox
BMW to introduce dual-clutch gearbox
http://www.caradvice.com.au/2966/2008-bmw-m3-m-dct-gearbox/
M3, meet DSG: BMW M3 gets 7-speed double clutch 'box - Autoblog

I'm also leaning towards Getrag as it has been rumored for something like a year now. This transmission has mostly been mentioned in the speculations: GETRAG Corporate Group - 7DCI600 TRANSMISSION But I'm still waiting for the press release from Getrag (or from another company).

 

[Zafiro]

PRICE FOR DCT in USA. OFFICIAL: $2,700.
(Price for SMGII for M3 E46 was $2,400)


BMW just announced that the DCT will be available in the U.S for the coupe beginning with the March production, and for the sedan beginning with the June production.

 

[Merc1]

Press Release

New seven-speed transmission adds performance, even more refinement to BMW M3

Incomparably smooth, silky gearshifts in the blink of an eye, improved fuel economy and reduced emissions are just some of the benefits of the ground-breaking seven-speed M double-clutch transmission with Drivelogic that has been developed by BMW M GmbH for the new BMW M3 Coupé, Sedan and Convertible.

On top of these benefits, the new M double-clutch transmission with Drivelogic is able to produce lightning-fast gearshifts that result in accelerative abilities exceeding those of the six-speed manual transmission version of the new BMW M3.

The BMW M3 Coupé with M double-clutch transmission with Drivelogic is able to accelerate from zero to 100km/h in just 4.6 seconds, or 0.2 of a second faster than the manual six-speed version, while returning an average fuel consumption of 11.9 litres/100 km.

As the world’s first seven-speed double-clutch gearbox developed for a high-torque, high-speed powerplant, the new BMW M double-clutch transmission with Drivelogic simultaneously lifts refinement and efficiency to new levels while providing the driver with a wide range of options that adapt the system to the needs of the moment.

The new transmission offers as many as eleven driver-selectable electronically controlled driving program choices.

These include five shift programs in the fully automatic mode and six in manual mode, and are supplemented by a selectable Launch Control program that provides blistering off-the-line acceleration where the power from the 309 kW, 4.0-litre V8 M3 engine is transferred with maximum effect to the road.

The heart of the new BMW transmission is the double clutch system that acts to smooth out gearshifts to the point that they are often only discernible by watching the rise and fall of engine rpm on the M3’s tachometer.

Each oil-cooled wet clutch activates its own set of ratios - one is used for first, third, fifth and seventh gears, as well as reverse, while the other looks after second, fourth and sixth gears.

Gearshifts are effected by the disengagement of one clutch and the engagement of the other, moving seamlessly from the ratio in use to the next, preselected ratio.

The fact that the next ratio is preselected and engaged merely by activation of the clutch is the secret behind the amazingly smooth and efficient transition from gear to gear.

Combined with the BMW Drivelogic system that, as well as offering the driver a choice of seven specific operational modes, is also able to determine the appropriate mode according to the current driving style, the new transmission’s multi-faceted nature allows it to offer anything from rapid-fire F1-style shifting to smooth, luxurious behaviour suited to relaxed boulevard cruising.

The new M double-clutch transmission with Drivelogic also incorporates a Low Speed Assistant mode that operates when manoeuvring at speeds less than 5 km/h to significantly increase the smoothness and degree of accelerator control available to the driver.

Gradient detection also means that the new M double-clutch transmission with Drivelogic is able to determine the appropriate ratios when travelling up or down hills.

This avoids the "hunting" between gears so often experienced in regular automatics when travelling on undulating roads, while the appropriate selection of lower gears on downhill gradients helps maintain road speed by using the braking power of the engine.

The new M double-clutch transmission with Drivelogic also offers the driver the choice of sequential operation via a sports selector lever in the centre console, or solid aluminium F1-style paddles on the steering wheel - right side for upshifts, left side for downshifts.

The range of shift programs available to the driver means it is possible for the M3 to behave with the grace and aplomb of a luxury car, or with the knife-edge rapidity and precision of a racecar - or anything in between.

In fully automatic D mode, the driver can select from five Drivelogic programmes that regulate both the gearshift speeds and the change points right through to the D5 mode where the engine is stretched close to its maximum rpm - depending on throttle position - on upshifts. In D1 mode, the M3 with M double-clutch transmission with Drivelogic is able to start off in second gear to help avoid wheelspin in slippery conditions.

In manual mode, six different Drivelogic programmes allow a similar range of characteristics, with the added driver control provided by the ability to choose shift points manually. In S6 mode, the drive can also activate launch control by holding the shift lever in the forward position.

In keeping with the overtly dynamic abilities of the new BMW M3, the M double-clutch transmission with Drivelogic, as well as being designed for engine speeds as high as 9,000 rpm, is also able to maintain correct operating temperatures even in the most extreme conditions - including racetrack operation - through its integration with the engine’s cooling system as well as the fact it also incorporates its own oil/air cooler.

The transmission’s interconnection with the engine cooling system also means a quicker temperature rise from startup, which contributes to reduced frictional losses and lower fuel consumption during the warm-up phase.

Faster shifting, smoother, and contributing even more to fuel economy and minimalised exhaust emissions, the new M double-clutch transmission with Drivelogic raises the bar for sophisticated, high-performance motoring to new heights.


New BMW M DKG Transmission


M

 

[klier]

^^^ It's really not easy to read an article on Worldcarfans without getting confused by a million advertisements on the same page.

Thanks for the article Merc. This new transmission sounds so yummy....

 

[S'Pimp]

Bravisimo!
M3 Coupe with M-DCT Drivelogic: + ~20kg
0 - 100kmh : 4,6sec
11 Programs - from comfort till racing
6 manual incl. Launch controll
5 automatic Programs

 

[vedjo01]

Bravisimo!
M3 Coupe with M-DCT Drivelogic: + ~20kg
0 - 100kmh : 4,6sec
11 Programs - from comfort till racing
6 manual incl. Launch controll
5 automatic Programs

Thats it..BMW M3 really shines with this tranny..I hope that real life impressions will be at the same level..

 

[wltsm]

This new transmissions seems very impressive!

Can't wait for the reviews to come out to see how good it is in the real world!

 

[S'Pimp]

interesting comparison

------------------------------------------------------------------M3QP---------------------------------- M3QP with M-DCT

Steering trans ratio: :1 ---------------12.5-------------------------- 12.5
Type of gearbox ------------------------SG 6 ---------------------M DCT Drivelogic


Gear ratios:

I :1 --------------4.055---------------------- 4.780
​

II :1 -------------2.369---------------------- 2.933​

III :1 ------------1.582---------------------- 2.153​

IV :1 -------------1.192---------------------- 1.678​

V :1 --------------1.000---------------------- 1.390​

VI :1------------- 0.872---------------------- 1.203​

VII :1 --------------*------------------------ 1.000​

R :1 --------------3.678---------------------- 4.454​

Final drive :1-----3.846---------------------- 3.154​

 

[Sunny]

That should really help with acceleration. 3rd in DCT is almost as short as 2nd in the manual and 4th, 5th, 6th and 7th is shorter than the previous gear in the manual. Heck, even 7th is not overdrive.

edit: didn't notice the longer final ratio, so the gear are not much shorter.

 

[S'Pimp]

4 visual comprehension

 

[coolraoul]

Sounds very impressive, bit I am a manual man...
But I have a question concerning the way a DCT works. This is a problem I had when trying the DSG in several VWs.

My problem with the Dual Clutch, is that they are not constant.

It is very fast and smooth. However, it sometimes is really very fast, sometimes a tad slower and less supple. Sometimes you don't feel the gearchange at all, sometimes you feel something. No big deal in a Passat, where the DSG really impresses.

However in a sportcar, on a track, I think it can be quite of a disadvantage not to know exactly how the gear will be changed.

All this comes from the second clutch. One is for 1-3-5 (-7?), the other for 2-4-6.
You are in 2nd at full throttle: logicly you soon will call the 3rd, not the 1rd, so the second clutch prepares the 3rd; then you call the 3rd: it is ready, it is super-fast. But if then you brake hard and call the 1st, it is not ready; it will be a bit longer.
This, in the DSG, explains why the gears are not all as fast and smooth.

I don't know if the M3 will solve this problem, that on a track can be annoying. I think, if you are in 2nd at fall throttle, the gearbox will prepare the next gear only when you reach the good regime: if you are at 6000rpm, it will prepare the 3rd, because you are less likely to call the 1st if you are at 6000rpm in 2nd. If then you brake hard the regime will fall, say at 4500rpm, then the gear will disengage the prepared 3rd and prepare the 1st instead...

This way the prepared gear would almost always be the right one, so the gearchange would always be as fast and as brutal or smooth.
This is already what the DSG does, but maybe less finely, less precisely?

However, this would mean that the gearbox would be at all time busy preparing another speed...Always working hard...So more power needed, more consumption...maybe less lifetime, because it would change or prepare millions of gears...

So I don't know. If someone can explain the logic used by this DCT...or maybe correct me if I am wrong with the way a Dual Clutch Transmission works? If BMW found a solution to this problem?

 

[Imhotep Evil]

I was gonna point this too.

 

[EnI]

^

Always a step ahead when shifting gears.

The M double-clutch transmission with Drivelogic combines two gearbox components in one common housing with the same compact dimensions as a conventional manual gearbox. The “heart” of the new M double-clutch transmission in technical terms is formed by the two oil-cooled wet clutches. One of the two clutches is for the even (2, 4, 6), the other for the uneven (1, 3, 5, 7) gears and, in addition, for the reverse gear.

While driving, one of the two clutches is always closed, the other is open. When accelerating – and when shifting down – the clutches are activated in an alternating process, one after the other. When shifting gears, therefore, the first clutch opens just as the second clutch is closing. This ensures an absolutely smooth and comfortable and at the same time an incomparably fast gearshift without the slightest interruption in the flow of power.

This interaction of two clutches ensures an unparalleled rate of gear change in particular because the transmission control unit pre-selects the next gear with the transmission ratio matched ideally to engine and road speed and keeps this gear waiting for immediate operation. So if the BMW 3 Series is accelerating, say, in third gear, an immediate flow of power is ensured by the appropriate clutch and the gearbox component controlling the uneven gears.

While all this is happening, the gearbox segment responsible for the even gears shifts to the gear required, in this case to fourth gear. The only operation required for this purpose is to close the clutch for fourth gear, at the same time opening the clutch for third gear, the power of the engine then being transmitted through the new gear with its different ratio to the wheels.

This entire process takes only a few milliseconds, meaning that in the time even a skilled driver takes to press down the clutch pedal the M double-clutch transmission with Drivelogic has easily completed the entire process of shifting gears, continuing to accelerate in the next gear higher up.



Like in motorsport: dynamic torque peaks when shifting up, in-between gas when shifting down.

With the process of engaging and disengaging the gears continuing in a smooth flow, the positive engagement connecting the engine to the transmission is not interrupted, allowing the driver to set off smoothly and comfortably and, in particular, to shift up at an incomparably fast speed. To provide an even more sporting driving impression and to further improve the car’s acceleration, the M double-clutch increases torque and pulling power to an even higher standard when shifting gears by means of the appropriately configured Drivelogic programs. In conjunction with the small increments between gears, these Drivelogic programs give the driver an even more intense feeling of acceleration, sensing each gearshift as the starting point for an even greater surge of power. The additional power generated in this way comes out clearly in the new transmission ratio feeding torque and traction to the drive wheels.

The combination of short gearshift times, small gear increments and the increase in torque gives the driver of a BMW M3 with an M double-clutch transmission a new, unprecedented experience of driving dynamics carried over directly from motorsport.

When shifting down the M double-clutch transmission works according to exactly the same principle. The only difference is that the electronic transmission control makes the process of engaging the clutch smoother and softer to prevent the rear wheels from being slowed down suddenly and with too great an effect.

Should the electronic control unit – for example when the driver is driving the car in an extremely sporting style or applying the brakes hard – recognise a very large gap in engine speed when changing gears, it will automatically adjust the transition of torque to the speed of the engine. This process of giving gas in between gears serves to further enhance the car’s driving stability and makes the entire driving experience even more intense. The drag force exerted by the engine comes out only to the extent desired by the driver, remaining within the limits already well known from cars with a manual gearbox.


Source: BMW AG

 

[Zafiro]

DCT is the latest technology in seqventiell gearboxes. This isnt just a copy of the DSG found in VW, its a more advanced version. Its a better improved gearbox and its going to make the SMG ancient.
I'm certain BMW done their homework and it will be weapon of choice for the track gurus. And DCT wont make the M3 a less fun car than a manual M3.

I've been told but I can't confirm it that the M3 DCT is three seconds faster around N-ring than a Manual M3.

 

[coolraoul]

^
The “heart” of the new M double-clutch transmission in technical terms is formed by the two oil-cooled wet clutches. One of the two clutches is for the even (2, 4, 6), the other for the uneven (1, 3, 5, 7) gears and, in addition, for the reverse gear.

While driving, one of the two clutches is always closed, the other is open. When accelerating – and when shifting down – the clutches are activated in an alternating process, one after the other. When shifting gears, therefore, the first clutch opens just as the second clutch is closing.

the transmission control unit pre-selects the next gear with the transmission ratio matched ideally to engine and road speed and keeps this gear waiting for immediate operation. So if the BMW 3 Series is accelerating, say, in third gear, an immediate flow of power is ensured by the appropriate clutch and the gearbox component controlling the uneven gears.

While all this is happening, the gearbox segment responsible for the even gears shifts to the gear required, in this case to fourth gear. The only operation required for this purpose is to close the clutch for fourth gear, at the same time opening the clutch for third gear, the power of the engine then being transmitted through the new gear with its different ratio to the wheels.

Source: BMW AG

Thanks EnI.

But my question: here in the example, the car is accelerating and in 3rd, so the gearbox prepares the 4th. It will then swift from 3rd to 4th very quickly, without power interruption.

However, if instead of calling the 4th, the driver calls the 2nd, because there is a corner and he brakes hard... The 2nd is not ready, the gearbox will have to switch to the 2nd instead of only engaging the clutch. Therefore, the gearchange will ba a bit slower, and there will be a little power interruption because the process is not as quick.

Is it right?

And in that case, what happens?

-> the gearbox disengages the clutch immediately after the gear call, and the power is interrupted and the gearchange slower. It means, immediately after the gear call the driver feels the order applied by the gearbox, but the process is slower than usual and there will be power interruption.

-> or the gearbox does not react immediately to the gear call, it means it prepares the gear and only then disengage the clutch. So the gearchange itself won't be longer, but there will be a longer delay between the gearchange order and the effective gearchange?

 

[Zafiro]

seriously CoolR I think you worry to much
This is BMW we talking about and they are not making the new gearbox worse than SMG. We are talking about the latest state of art in seqventiell gearboxes, more advanced than any DSG VW has to offer for right now.
BMW has done their homework, dont expect anything less.

Wait for some reviews and you will get your questions answered.

 

[EnI]

Exactly.

Do you really think BMW would equip an M car with exactly the same DCT tech as used in eg. VW Golf or Golf Plus???? I'm sure BMW 7-speed DCT is more advanced & more sporty than the one used in VW cars.

C'mon we are talking about M car here, not an economy hatch.

 

[coolraoul]

I never said it will be the same as the DSG. I perfectly know BMW would never use the same gearbox as a VW in an M3!

I only had questions about the technical principles behind a double-clutch gearbox, and the way it works!

Don't take it as a criticism, it really isn't, only a question I was asking myself and therefore I wanted to know if someone had details about it.

BMW uses it, AMG and Porsche will (actually Porsche invented the concept for one of its racecars), so it sure is a logical improvement of the sequential technology.

However I wanted to know how the gearbox decides to prepare this or the other gear, as it always have the choice between two gears to prepare, that's all! And what happens exactly if it prepares the wrong one!

 

[Zafiro]

I never said it will be the same as the DSG. I perfectly know BMW would never use the same gearbox as a VW in an M3!

I only had questions about the technical principles behind a double-clutch gearbox, and the way it works!

Don't take it as a criticism, it really isn't, only a question I was asking myself and therefore I wanted to know if someone had details about it.

BMW uses it, AMG and Porsche will (actually Porsche invented the concept for one of its racecars), so it sure is a logical improvement of the sequential technology.

However I wanted to know how the gearbox decides to prepare this or the other gear, as it always have the choice between two gears to prepare, that's all! And what happens exactly if it prepares the wrong one!

Wait for the tests, its impossible to discuss without any info or testdrives. You are going to fast Mr Cool. Calm down and let the press do their testdrives first
While you're waiting, read the long pressrelese if you havent done that already.