MB following firmly in BMW's footsteps

[gorun]

Glad to see that the competition is making good use of BMW's inventions. Last week when the facelifted SLK came out MB announced thats its going to feature and optional direct steer system similar to the active steering pioneered by BMW. This week when the facelifted SL63 AMG was announced MB confirmed that its going to ditch the torque converter auto for this model in favour of a SMG type system called MCT. Its going to feature a single robotised clutch.

[swamp2]

^ automated manual ala SMG with a single clutch was offered on the E36 M3 how long ago??? MB - time to get with the times and offer a dual clutch.

[gorun]

The MCT offers 100 ms shifts in best mode. Wasnt the SMG faster (80ms if memory serves me right). Eventhough its no dual clutch its going to make the Sl63 mighty quick. No torque converter power sapper + the MB performance package should make for an entertaining drive. I fear, however, that when specced properly its going to be north of 150 000 Euro.

[swamp2]

Originally Posted by gorun

The MCT offers 100 ms shifts in best mode. Wasnt the SMG faster (80ms if memory serves me right). Eventhough its no dual clutch its going to make the Sl63 mighty quick. No torque converter power sapper + the MB performance package should make for an entertaining drive. I fear, however, that when specced properly its going to be north of 150 000 Euro.

BMW claimed 80 ms shift times for SMG II, reality through testing with accelerometers was more like .20 -.25 seconds (200-250 ms).

BMW claimed 65 ms shift times for SMG III, again reality through testing showed about 150 ms.

BMW claims shifts in "milliseconds" for M-DCT. To me that press release means <10 ms. I think in reality we will see shift times < 50 ms for sure, maybe 30 ms.

[jaiman]

"The engine is coupled to a newly developed seven-speed multi-clutch transmission exclusive to the SL63 that Mercedes says combines the convenience of an automatic with the direct connection of a manual gearbox and "the lightning-quick automatic gear shifts of a Formula 1 race car." The tranny features a start-up wet clutch that replaces a conventional torque converter and features four shift modes and a double-clutching function."


http://www.autoweek.com/apps/pbcs.dl...8/newsletter01

[mkoesel]

I was wondering when I'd see a thread on MCT around here. Googling it turns up a little more info, but I still want to know more about modes and times. I suspect that the '09 or '10 C63 will get this tranny.

[swamp2]

Originally Posted by jaiman

"The engine is coupled to a newly developed seven-speed multi-clutch transmission exclusive to the SL63 that Mercedes says combines the convenience of an automatic with the direct connection of a manual gearbox and "the lightning-quick automatic gear shifts of a Formula 1 race car." The tranny features a start-up wet clutch that replaces a conventional torque converter and features four shift modes and a double-clutching function."


http://www.autoweek.com/apps/pbcs.dl...8/newsletter01

I know you probably are not but for those that may be confused by this marketing speak neither multi-clutch or double clutching FUNCTION are anything like a true dual clutch transmission whatsoever. This is an automatic transmission, albeit a pretty fast/nice/advanced one.

[lucid]

Originally Posted by swamp2

I know you probably are not but for those that may be confused by this marketing speak neither multi-clutch or double clutching FUNCTION are anything like a true dual clutch transmission whatsoever. This is an automatic transmission, albeit a pretty fast/nice/advanced one.

Are you saying that MCT does not have 2 clutches? What are the specs for this transmission exactly?

[chicagobimmerboy]

They might follow but BMW leads the way!!! that is why I would never step out of the ring for a Benz or Audi.

[gorun]

Originally Posted by swamp2

This is an automatic transmission, albeit a pretty fast/nice/advanced one.

Its not an auto but smg. No torque converter!

[sayemthree]

last MB i drove was like piloting and med. size boat.

[dechoong]

Originally Posted by gorun

Its not an auto but smg. No torque converter!

It is an auto... albeit an updated one.

What’s so clever about the SL63 AMG's new gearbox?

While everybody is rushing down the dual-clutch sequential-manual route, Mercedes has taken a different path. It reasoned that semi-auto ’boxes spend most of their time in full automatic mode, which is precisely when they are at their least impressive. A traditional epicylcic automatic gearbox provides much smoother gearchanges and is more compact – re-engineering the floorpan of existing cars to accommodate a new gearbox is an expensive business.

But the torque converters they use rely on fluid pressure to connect engine to gearbox and are only locked up solid part of the time. This, and the weight of the torque converter, hurts throttle response and efficiency. So Mercedes got clutch experts Sachs to add a wet-plate clutch to its existing seven-speed gearbox. A dry clutch would have been even lighter and more efficient but wouldn’t have been able to dissipate the heat generated when transmitting the V8’s twist to the wheels.

On the whole it works very well. Only a very slight judder when creeping in traffic gives any clue to this being anything but a normal automatic. And left in D – which, let’s face it, is where most automatics and DSGs spend their time - it slips between ratios as seamlessly as any other Mercedes without a clutch pedal. But attempt to add any juice and you can feel the extra response. The V8 feels light and eager to rev and there’s none of the slurring you get when coming on the power with many autos. Occasionally you get the odd uncultured jolt as different ratios are selected and sometimes you don’t get the gears the instant you select them (an AMG insider blames the cheap steering wheel switches), but this is an impressive attempt to marry auto and manual transmissions. For now only the SL63 gets this box (the SL65 is too torquey) but you can bet that it will find its way into more humble machinery over the next couple of years.

http://www.carmagazine.co.uk/Drives/...ontent-block=1

[mkoesel]

Thanks for that dechoong. Informative.

I still don't have a clear picture of how thing thing works. When I think of clutch in a transmission, I am thinking of something that needs actuation to engage or disengage. Is this a centrifugal clutch, like on a go-cart? Is it like a torsion differential? Is it something else? I know its a wet clutch but that does not explain how it operates exactly.

[MontegoblueE92]

Originally Posted by swamp2

^ automated manual ala SMG with a single clutch was offered on the E36 M3 how long ago??? MB - time to get with the times and offer a dual clutch.

It actually started with the E46. I believe it was 04 right? But even though BMW states 80ms shift times, I sometimes think that is the time it takes to just change the gears, not including disengaging and engaging the clutch. I might be wrong, but it just never seems anywhere near what they state the times as being.

[mkoesel]

Originally Posted by MontegoblueE92

It actually started with the E46. I believe it was 04 right?

No, SMG I was debuted on the E36, but never made it to the US I don't think. Also SMG II was on the E46 as of MY 2002, or perhaps even earlier in other countries.