02-13-2015, 05:22 PM | #67 |
World's Foremost Authority
1181
Rep 4,535
Posts
Drives: M4 Cab - Cayenne GTS - Jag XK
Join Date: Jul 2007
Location: Upper East Side Manhattan - Boca Raton FL - Lime Rock CT
|
It may be fun when you are driving at 6/10 but when you are at the limits it will upset the car. The last thing I want is a car with a transmission that emulates a poorly driven MT.
__________________
Drivers Club at Lime Rock - International Motorsports Research Center - Society of Automotive Historians - Madison Avenue Sports Car Driving and Chowder Society (0nly a VP) - BMWCCA - Porsche Club of America - M Gruppe - Polish Race Drivers of America (PDRA) - Glen Club (Watkins Glen International) - Jaguar Club of Southern New England |
Appreciate
0
|
02-13-2015, 09:10 PM | #68 | |
Major General
6592
Rep 6,692
Posts |
Quote:
Some of the posters above are steering you off track. I mentioned the torque converter not because it's the only way to get smooth take offs, but because of HOW IT WORKS. A torque converter uses two "fans" essentially, spinning in fluid (ATF). Very simply put, the "fan" on the engine side spins as the engine speeds up. At first, nothing happens. But as the "fan" spins faster, the fluid's shear eventually starts to transmit force to the other "fan" and the wheels receive power. This is very gradual and soft, hence "smooth starts". At some point, the two sides will lock together using a clutch, and you will have no loss due to the heat in the fluid. Because the DCT has no torque converter, it uses a clutch to engage the drive side (engine) to the driven side (wheels) (two actually, one for odd gears, the other for even). So it's engagement behaves the same way that a manual transmission would. Here is the difference. In a traditional manual transmission, the driver is in charge of two things, throttle and clutch. You choose how many revs to add, and how quickly or gradually to engage the clutch. You control the smoothness of the engagement. In the DCT, you still control the throttle, but the computer controls the clutch. It needs to guess your intentions based on throttle input. So, if it senses you rolling into the throttle, it'll engage the clutch slowly. Jam into the throttle, and it'll slam the clutches shut, expecting that you'll want a fast takeoff. So the trick is that you need to work simpatico with the computer that's engaging the clutch. Since there is no fluid filled torque converter damping out any differences, you're going to feel when you and the computer are at odds with one another. I won't get into shifting underway, as that's usually not as much of an issue. Hope this helps. |
|
02-13-2015, 09:57 PM | #69 | |
World's Foremost Authority
1181
Rep 4,535
Posts
Drives: M4 Cab - Cayenne GTS - Jag XK
Join Date: Jul 2007
Location: Upper East Side Manhattan - Boca Raton FL - Lime Rock CT
|
Quote:
__________________
Drivers Club at Lime Rock - International Motorsports Research Center - Society of Automotive Historians - Madison Avenue Sports Car Driving and Chowder Society (0nly a VP) - BMWCCA - Porsche Club of America - M Gruppe - Polish Race Drivers of America (PDRA) - Glen Club (Watkins Glen International) - Jaguar Club of Southern New England |
|
Appreciate
0
|
02-13-2015, 10:03 PM | #70 |
Lieutenant General
14030
Rep 10,080
Posts |
In normal D1 driving I don't really notice a difference from my 335s ZF8. I have not experienced any of the jerkiness that some are describing here.
|
Appreciate
1
|
02-13-2015, 11:03 PM | #71 | |
General
21117
Rep 20,741
Posts
Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal
|
Quote:
How about when you lift off the brake when the vehicle is stationary, does the DCT creep forward as the ZF8 did?
__________________
Porsche 911 turbo 2021 992 GT Silver
Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black |
|
Appreciate
0
|
02-13-2015, 11:06 PM | #72 |
Major General
1125
Rep 6,067
Posts |
Bingo... This is more than enough reason why I love DCT over ZF8
__________________
Current : 2020 F92 Black Sapphire M8 - ZF8
Gone : 2018 F80 Mineral Gray M3 - 6MT Gone : 2016 F82 Austin Yellow M4 - 6MT Gone : 2013 F13 Sakhir Orange M6 -7DCT Gone: 2013 F13 Alpine White 650i -ZF8 |
Appreciate
0
|
02-13-2015, 11:11 PM | #73 |
Lieutenant General
14030
Rep 10,080
Posts |
No it doesn't. I was more comparing the two on smoothness while shifting and starting off. The only difference I notice is when the car isn't warmed up it feels like the clutch in the DCT is slipping. This goes away quickly when it warms up.
|
Appreciate
0
|
02-13-2015, 11:48 PM | #74 | |
Mlightened
1852
Rep 2,242
Posts |
Quote:
And here's my .02 cents worth of opinion as I have figured out a little more of why it bucks as stated above with some of my experience with this tranny, having broke the car in finally I realise this car likes to rev....if you step on it whether you're smoothly pressing into the throttle or stomping it only to slightly back off as you go into second gear(manual or auto) the DCT gets confused at your intentions.....do you want to "go"....or not.... If you rev the engine out I promise you the jerkiness/bucking will smooth out. If you want to do two second bursts from the light.....bad move, the DCT doesn't like this....it wants and thinks you wanted to "go"....but then you backed off...thus leaving it hanging....so it bucks and jerks in an attempt at quickly sort of trying to work out whether it should shift up or down or if in manual whether to slam the next gear in now or just be "prepared" for the next gear. It has nothing to do with whether people came from previously driving a DCT car or not, this transmission and engine have a learning curve. I bet most are bucking and jerking with the throttle in Sport or Sport +.......or have the DCT in the second or third setting....yet when they roll the throttle on as smooth as you want to be....but back off just as the revs climb then the jerking begins....which is why a lot are saying to quickly shift to second....yeah that will work but it isn't the answer.... You either want to go...and keep "going" with your settings "other than comfort" or you don't, in which case you should have all your settings in the most comfort settings. This is almost a racecar...almost....except with a shit ton of creature comforts and maybe four doors. Try it...keep your settings higher than comfort and leave that light with your foot on the gas and don't let off, but "conservatively" shift at 4-5k to second, smooth as butter.... or Put everything in soccer mom mode and leave that light like your in a school zone at 8am.....smooth as butter... but...switch settings to sport and leave from a stop like a drag strip but let off to go in a school zone while the revs climb and the DCT is like WTF....."tease!" = buck/jerk.... Remember, you have all the torque at 1850rpms....that's ludicrous....bottom line, learn to drive your car and drive with correct intention, no half assing. |
|
Appreciate
2
McBobby Jr212.00 |
02-13-2015, 11:52 PM | #75 |
Colonel
552
Rep 2,633
Posts |
Dude if you want 0 feel from the transmission get a 335 with and automatic transmission. The jerkiness is the clutch engaging! I hope BMW never makes the DCT feel like an automatic. Anyone that has owned an M or understands what a sports car is supposed to feel like would never say this transmission Is jerky.
|
Appreciate
0
|
02-13-2015, 11:59 PM | #76 | ||
...
11827
Rep 15,400
Posts |
Quote:
__________________
Quote:
|
||
Appreciate
0
|
02-14-2015, 03:16 AM | #77 |
World's Foremost Authority
1181
Rep 4,535
Posts
Drives: M4 Cab - Cayenne GTS - Jag XK
Join Date: Jul 2007
Location: Upper East Side Manhattan - Boca Raton FL - Lime Rock CT
|
No transmission should ever feel jerky whether it is an AT a DCT or an MT. I don't know why some people equate rough shifts with performance. Fast driving is smooth driving, jerkiness and roughness scrub off speed and upset the balance of the car,
__________________
Drivers Club at Lime Rock - International Motorsports Research Center - Society of Automotive Historians - Madison Avenue Sports Car Driving and Chowder Society (0nly a VP) - BMWCCA - Porsche Club of America - M Gruppe - Polish Race Drivers of America (PDRA) - Glen Club (Watkins Glen International) - Jaguar Club of Southern New England |
Appreciate
0
|
02-14-2015, 06:58 AM | #78 |
General
21117
Rep 20,741
Posts
Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal
|
What does not help is the uselessly short first gear ratio.
I have ranted many times about BMW going cheap by giving us a "hand-me-down" DCT from the F1X M5/6.
__________________
Porsche 911 turbo 2021 992 GT Silver
Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black |
Appreciate
0
|
02-14-2015, 07:37 AM | #79 | ||
Major General
6592
Rep 6,692
Posts |
Quote:
As I said, and as you alluded to, once underway, shifts in D1 are very similar to those of the ZF8. Downshifts are noticeably better, IMO. |
||
Appreciate
0
|
02-14-2015, 08:17 AM | #80 | |
Captain
459
Rep 843
Posts |
Quote:
__________________
Future Order: 2022 M4 Comp X, Portimao/KO
Previous: 2018 M3 ZCP, YMB/Silverstone 2015 M3, SO/Black |
|
Appreciate
0
|
02-14-2015, 08:32 AM | #81 | |
World's Foremost Authority
1181
Rep 4,535
Posts
Drives: M4 Cab - Cayenne GTS - Jag XK
Join Date: Jul 2007
Location: Upper East Side Manhattan - Boca Raton FL - Lime Rock CT
|
Quote:
1. "Drive what you're in" 2. "If what you are doing isn't working try something else" The M3/4 needs to be approached cautiously and carefully, When driven conservatively it can be very docile and to many drivers it will seem very much like a regular 3/4 series. But never forget than when provoked it can turn on you very quickly. CA
__________________
Drivers Club at Lime Rock - International Motorsports Research Center - Society of Automotive Historians - Madison Avenue Sports Car Driving and Chowder Society (0nly a VP) - BMWCCA - Porsche Club of America - M Gruppe - Polish Race Drivers of America (PDRA) - Glen Club (Watkins Glen International) - Jaguar Club of Southern New England |
|
Appreciate
2
|
02-14-2015, 01:37 PM | #82 |
Captain
87
Rep 725
Posts |
Like people have said, the DCT just definitely takes some getting used to. It doesn't drive like anything else. You'll find the sweet spot.
__________________
2016 340i M-Sport 6-MT(on order)
2013 335is (still have) 2011.5 M3 ZCP (traded in) |
Appreciate
0
|
02-14-2015, 02:34 PM | #83 |
Second Lieutenant
95
Rep 266
Posts |
no problem at all. Maybe because I do what some have said about the "speaking" my intentions to the computer. I've found out that if you treat the car more like a manual you get better results or at least I am. I remember when doing my driving exam the examiner told me i shift like AT
Anyway, just know what you want from the car. For smooth start dont hit hard the throttle back off and expect everything to be super smooth, be gentle like it's a woman
__________________
Nothing's worse than regret.
|
Appreciate
0
|
02-14-2015, 03:29 PM | #84 | |
Lieutenant
624
Rep 426
Posts |
Quote:
On topic: I like the DCT. I know it can be jerky sometimes. I had the same issue when I got the M4. Now is a different story. Its like they said. You have to communicate with the car and find the sweet spot. After you find it its really nice |
|
Appreciate
0
|
02-15-2015, 10:18 AM | #85 | ||
Colonel
1163
Rep 2,561
Posts |
Quote:
And I do find that F80 DCT in the most docile setting is as smooth as ZF8, and works perfectly in 'auto' D mode. a
__________________
'19 TM3P (BK/BK)
'15 F80 M3 (SO/SS) ex-'17 I01 i3-BEV (PB/DD), ex-'15 I01 i3-REX, ex-E90, E46, E36's, E30's |
||
Appreciate
0
|
02-15-2015, 10:55 AM | #86 |
Major General
1125
Rep 6,067
Posts |
You are right but I was talking about "feeling"... the difference between rolling (the same as MT) and creep (torque converter)...
__________________
Current : 2020 F92 Black Sapphire M8 - ZF8
Gone : 2018 F80 Mineral Gray M3 - 6MT Gone : 2016 F82 Austin Yellow M4 - 6MT Gone : 2013 F13 Sakhir Orange M6 -7DCT Gone: 2013 F13 Alpine White 650i -ZF8 |
Appreciate
0
|
02-15-2015, 11:58 AM | #87 | |
Lieutenant General
18170
Rep 11,758
Posts
Drives: 2018 M4 Comp Indv
Join Date: Jun 2009
Location: Newport Beach
|
Quote:
Once we clear away the "dude you suck" answers, the "jerky start" is a good question if cold-start jerkiness is what the OP is getting at ... On the E9x - cold-start-then-drive was jerky as hell no matter what mode (and no matter what is going on technically). My wife hated that car, and it was DEFINITELY slipping the clutch. Anyone who's driven a MT for years knows the sound when you take your foot off the clutch slowly ... or you drive a new stick you've not been in before and you can overrev-overslip on your first go. Well the E9x did that big time and then gave you a very touchy throttle for about 60-120 seconds on cold start. There was no driving style to fix it except just letting the car warm up. The F8x is WAY better. It also does a bit of clutch slipping as minn19 notes but it's much less noticeable and much easier to control than in the E9x. Also I've noticed that the F8x goes for second gear right away. Anyway, my wife says the jerkiness is gone but I suspect that's only because she had to occasionally drive the E9x for 3 years So in my experience it's the combo of Needsdecaf and minn19 that's the right answer. |
|
Appreciate
0
|
02-16-2015, 12:39 PM | #88 |
Lieutenant
246
Rep 435
Posts
Drives: 2017 BMW M4CP SO
Join Date: Feb 2015
Location: London
|
I'm new to DCT (drove 335i auto before) and I experienced some jerkiness in first few weeks driving my M4. It happened in 1st gear, Sequential mode, Sport/+, in city traffic where I couldn't properly put my foot down. My conclusion was that essentially you can't drive this car like a pussy in Sport/Sequential mode, being indecisive with the throttle. The car thinks you really want to go fast, but then you don't and it jerks. This seems to be consistent with what few people wrote here already, so I'm just sharing my experience. Who would have guessed that an M car actually takes some skill to drive . I think you just need to get used to it being different.
|
Appreciate
0
|
Post Reply |
Bookmarks |
|
|