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Old 02-28-2011, 08:32 AM   #9 (permalink)
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From what I have read (not a whole lot) the dual clutch 6 speed is a manual transmission that has clutches controlled by a computer. If that is the case then neutral would cause no problems with lubrication of the gears, shafts, and bearings.

This is completely different from a conventional automatic.

The question is how are the two clutches controlled. I would ASSUME (sometimes a big mistake) the clutches are disengaged by hydraulic pressure. The reason for this is they are disengaged for a small amount of total operational time so that would be more efficient.

Wet clutches that are disengaged hydraulically may not work properly if the engine is not running to produce hydraulic pressure. The rest of the transmission being basically two 3 speed gearboxes combined should be fine without pressurized lubricant, but even that may not be correct, but it is probably correct.

I certainly would not want to be the first to experience a transmission failure, only to find that the manufacturer can avoid paying for any repair because they can prove you were using a method that is strictly prohibited in the owners manual.

If, like Fords DC 6 speed, the clutches are dry then I would feel more confident about neutral coasting. If the clutches are wet, I would probably not try engine off operation when the car was moving.

Typical band operated planetary gear set multi speed AT's require pressure to operate the individual gear sets, which without pressure would burn up fairly quickly, unless you leave the engine running.

On my car I have never and probably will never coast in neutral with the engine off, since the CVT requires hydraulic pressure to control everything, which I do not think is the case with a DC 6 speed, but you must also consider the computer controls may not function with the engine off.

Get a price on a new transmission if you decide to take any risk whatsoever. Probably over $5K.

regards
Mech
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