AMG's new 7-speed auto transmission has no torque converter! It uses a wet clutch. Because there is no big commentary on this, I have to write my own bullshit, here goes.
Many many months ago, German engineers from Mercedes put out a cryptic comment during journalists' query on why pre-production Merc C63 AMG had no DSG. They said... `let's see what's coming out in March 2008.
I waited with bated breath.
In the press release yesterday, they even tried to confuse the public by using words like `double declutch' to let the average think that this is a dual clutch transmission.
They needn't actually, because the result is a really supreme auto transmission.
This transmission is only available in the new SL63 AMG but definitely it will be transferred down all the way down to the C63 AMG, since it is extremely light at 80kg only, lighter than the current C63 transmission.
This is NOT a dual clutch transmission, although they use words like double declutch (utterly not related) and Multiclutch (which is debatably a bad use of the word, but germans can get away with murder where translations are concerned). The difference compared to a normal auto transmission is that it replaces the torque converter, which functions as an impact buffer, with a wet clutch bathed in oil combined with a torsion damper. Because it has no more torque converter, you will not notice the TC slip symptoms which plague lesser transmission, but obviously it still slips a little bit though much less - that's the function of a clutch, so don't BS us with the words `no slip', AMG!
Presumably, they still use the hydraulically driven planetary gearset patented by Getrag for transmission shifts. The great thing is that they use double declutch for downshifts, for ultimate smoothness and elimination of wear. Since they did away with the torque converter, this HAS to be done, because the wet clutch presumably cannot handle sudden driveline shunts. Good consequence though, a really really exciting downshift solution for a TC-less setup.
IN DETAIL: AMG SPEEDSHIFT MCT 7-SPEED SPORTS TRANSMISSION - German Car Scene
and here's my original google search this morning:
amg 7-speed transmission no torque converter - Google Search
Paul Tan a Malaysia commentator says that this is a DSG:
New dual-clutch 7-speed AMG SPEDSHIFT MCT
but I submit that he is wrong. He was misled by the words double declutch. It uses a SINGLE WET CLUTCH. A Single Wet Clutch has multiple plates, but they work as SINGLE CLUTCH and does not pre-engage as in DSG. (authority:
Motorcycle Glossary: Online Guide and Resources Directory or
Clutch - Wikipedia, the free encyclopedia) Wet clutches do have some power losses in the oil, but screw it, with so much torque who cares???
Whether this outperforms a DSG remains to be seen, but the plus points over a DSG are:
1) Light weight
2) Less moving parts = more reliable
3) Don't have the 600ms predictive miss penalty of normal DSG.
4) Who says auto can't shift fast? 100ms is fast enough!
Linear Mode
