12-02-2012, 05:40 AM | #45 | |
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12-02-2012, 05:53 AM | #46 | |
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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. |
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12-02-2012, 06:09 AM | #47 | |
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12-02-2012, 06:20 AM | #48 |
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Most DCT gearboxes are no faster than the ZF8AT. Also, DCTs are crap in traffic, much less smooth in their operation and can only go from odd to even or even to odd gears. Which would I prefer on a track? A DCT obviously. But which would I prefer to live with? That's a no brainer since the ZF8AT is the best gearbox in the world right now
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12-02-2012, 07:02 AM | #49 | |
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A DCT's advantage is its feel and connection with the car in manual mode and that is the only area where no AT can really compare. The DCT feels and acts like a true manual (because it is) and feels like a direct link to the car. In manual mode and in aggressive driving it is incredibly fun in a way an auto can't match yet. Driving around town, this connection and responsiveness is much less relevant and the DCT isn't as good in those circumstances for sure.
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12-02-2012, 07:07 AM | #50 | |
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12-02-2012, 07:10 AM | #51 | |
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12-02-2012, 07:17 AM | #52 | ||
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12-02-2012, 07:22 AM | #53 | |
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Anyway, I ordered it again on my oncoming M135i because of the great reviews. Cheers Robin |
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12-02-2012, 07:27 AM | #54 |
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Interestingly enough, my old man's got a 5GT (30D+8AT) at the mo and has been looking at a Panamera as his replacement. He spent a weekend with different models and concluded that he's probably going to get a 6GC instead because nothing Porsche has to offer can match the drivetrain of a BMW diesel with the 8AT Go figure!
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12-02-2012, 07:34 AM | #55 | |
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12-02-2012, 08:21 AM | #56 | |
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I will miss the opportunity to launch hard, but that is the only function that is not available on the ZF8. |
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12-02-2012, 08:49 AM | #57 |
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Dumb question... does the 8AT rev match and blip the throttle on downshifts when in manual mode?
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12-02-2012, 09:09 AM | #58 |
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I have a highway off ramp on a steep downgrade where I go from highway speeds at 80mph down a hill to 20mph to a stop in 10 seconds...this is where I've noticed the skip.
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12-02-2012, 01:43 PM | #60 |
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and it sounds like sex when you have the M Perf Exhaust...it's like a little burble blip, sounds wicked sick. I usually drive around town in Sport/DS mode just so I can hear it....
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12-02-2012, 05:45 PM | #61 | |
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Tightest feel goes to the dual clutch. Smoothness goes to the ZF, especially in day to day driving. Now, after posting all my praises for the ZF sport AT, my AT needs to be looked at. It's acting funny. When it's cold manual shifts are harsh and abrupt. Even after the engine and trans are very well warmed, manual shifts are not as smooth as they are in auto mode. Today I got some very odd trans behavior and frankly kind of dangerous. I was doing some tests of the trans and I got it to do an 8th to 2nd downshift amazingly fast. It was during accel. I was between 40-45mph trans was in AT in 8th. I stomped the throttle to the floor it kicked down to 2nd and took off like a rocket. LOVE the 3.0 turbo. Then I let things cool down and drove around in comfort auto mode. I switched to manual and was coming to a stop light. I down shift to 4th it's ok, then 3rd, but it was NOT smooth at all. The trans shifted to 3rd and the car JUMPED forward very aggressively, then I went to 2nd and it did the same thing, JUMPED forward hard. Luckily there was no one in front, but if there were I could have hit their bumper if I wasn't fast on the brake. I tested this out a couple more times and it did the same thing. It never did this before. I went shopping and then came back, started it up, drove, repeated the same test and the downshifts were smooth and rev matched as the should be. It felt like the "rev matching" wasn't working at all. I select a down shift to 3rd and it goes then lurches hard forward, not good. I've been wanting to take it in for a few weeks now, but without any codes I'm sure I'll just get the "no problems found" conclusion. Since trans performance seems to be getting worse I may hold out until something happens. I'll be on vacation around Xmas and won't be going out of town. If this happens again I'm going straight to the dealer, not shut the car off and have the service writer go for a drive. Hopefully I can repeat the problem. |
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12-02-2012, 05:51 PM | #63 | |
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You can do a hard launch with the ZF sport AT. Put the drivers mode in "sport+" and turn DSC/DTC completely off with the separate switch. Put your foot on the brake, rev the engine to around 2000 rpm and let the brake go with WFO throttle. It launches very hard and fast. You'll have to experiment with different rpm and modulate the throttle, because it can smoke the tires from a standstill if done that way. |
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12-02-2012, 05:56 PM | #65 |
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Yeah, I'm sure something is off because it was great when I first go it.
But from day 1 my AT didn't feel as smooth as the other AT's I had test driven, which was something like 8 of them. Auto mode is always extremely smooth with nearly no perception of the up or down shift. Manual mode is when it's not so smooth. I had a loaner a couple months ago, an F30 328i and it was much smoother in manual mode than mine. It wasn't a "sport AT", but down shifts were still much smoother. I would select a lower gear and I would see the tach move but barely feel the down shift. My AT doesn't feel as smooth, and it seems to be getting worse. |
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12-02-2012, 06:10 PM | #66 | |
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