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      12-02-2012, 06:53 AM   #46
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Drives: The best kind of F30 :)
Join Date: Aug 2012
Location: Bedford UK

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Originally Posted by gthal View Post
The best automatic gearbox on the planet, yes. It is a fantastic auto without a doubt but if you spent time with a DCT, I think you would agree it is better for sports driving. The DCT can effectively skip multiple gears with the shifter/paddles... if you are in 6th and click 3 times quickly, it immediately goes to 3rd. You don't have to actually wait for it to engage each gear (unlike my C63 where you have to let it go into each lower gear). The DCT also has the kick down feature.

It also shifts instantly up/down. I mean INSTANTLY. Click the shift paddle and the car is instantly in the next gear... aggressive shifting can actually be fairly violent as the tranny rams the next gear. It is actually what converted me (previously a 6MT only guy) into a true DCT nut. In full auto mode, I suspect the 8AT is better (as it wouldn't have some of the compromises of the DCT and would be smoother, etc) but in manual mode during aggressive driving, the DCT is simply amazing and cannot be beat. There is a reason BMW puts the DCT in the M3

Not exactly true on the DCT mode of operation. The DCT is like two gearboxes in one housing. When in 1st gear, second gear is pre-selected but disengaged by it's own clutch. Changing from first to second is a sequence of fading one clutch in as the other fades out. Not quite instantaneous as there is a period where both clutches are slipping, but pretty quick.

Typically, if you are accelerating up through the gears, there is logic that selects the next higher gear on the second gear set, however if you change down (out of the pre selected logic) it physically has to deselect then re-select another on the same gear set. This takes time. So if you select a gear the ECU thinks you are going to select it is quick, if you don't it needs to complete a slower change. None of this matters much to the user, as you can't physically slow down fast enough to catch the gearbox out.

The ultimate gearbox is that used in Formula 1, it is so fast it actually has two gears engaged for a split second at the same time (same gearshaft, not clutch de-coupled). This is known as seemless shift, the power is not even interrupted on up changes. But whilst on F1, not even an F1 car that pulls 5-6G deceleration needs to skip gears, so not quite understanding why a road car would need to unless the driver was a complete anus.