Autoblog

No Clue, but unlike an AT the DSG is far more similar to SMG, no torque converter, just computer actuated pair of clutches... actually in the GTI/GLIs case the DSG and the 6MT boxes are damn near identicle save the DSG's second clutch and computer. Audi's been selling cars with them for near half a decade and I have 35,000 hard miles on mine.

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I would guess that's it's much, much more expensive. The new Evo SST has the entire thing encased in a metal case. In a leaked tech memo to dealership technicians it says something to the effect of "no access to transmission internals is given -- any work requires a complete replacement with work being done by MMNA".

So, it's sufficiently complicated that they don't even want their dealership technicians working on it. Complicated probably means expensive at least for the foreseeable future.

The good news is that many manufacturers are extending their powertrain warrenties a la Hyundai so price shouldn't be as big of an issue.

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Durability was a major issue in the development of the new crop of dry dual clutch transmissions. Basically, the inner clutch in particular has to be cooled sufficiently or it will warp. Transmission manufacturers weren't able to prove to their customers that they had licked this problem - at least up to ~350Nm (~250 lb-ft) of torque - until recently. Current designs are expected to last as long as the engine, which is typically longer than the whole vehicle.

However, the various mechatronic and hydraulic actuators for the clutches and syncromeshes in a DCT aren't really much of a reliability headache. Critical corner cases such as a driver demand to suddenly drop from maximum torque to zero are anticipated and taken care of in the design stage. Compared to conventional AT with its torque converter, numerous clutches and belt brakes, wear and tear in a DCT is generally very low, less even than in a manual.

CVTs don't have much of durability problem as long as you stick to the prescribed change intervals for the special traction oil. This contains long-chained molecules that actually force the liquid to solidify momentarily under the high contact pressures between the belt and discs which are maintained by hydraulics that sharply reduce overal fuel economy. Some CVT designs (e.g. NuVInci, GIF KRG, ToroTrak) use differnet contact partners and more efficient mechanisms to generate the contact pressure, but they do all rely on traction oils to transfer torque.

The main snag is that a true CVT will force the engine to rev high before the car has gained much speed. This rubber-band effect sounds cheap, because it highlights the fact that the engine is smaller than usual (cp. kickdown with a conventional AT, but smooth). The discrepancy between engine sound and vehicle speed takes some getting used to, though Japanese kei car drivers don't seem to mind much. Simulating discrete gears recreates the aural effect of a step-by-step transmission, but if that's what you want, there are several cheaper alternatives.

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Sorry, typo...

35 kgm = 253 lb-ft.

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Coming from an engineering background, I actually prefer metric, but to each his own.

Anyway, readers could easily be less "lazy" and type in '35 kg*m in pound*feet' sans quotes right into google.

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I'm an engineer also, so it's metric for me unless it's something mundane and household, like a '2x4'

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@rqseidl

Good post--thanks!

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