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2019+ BMW 3 AND 4-SERIES FORUMS (G2x Generation) General G80 M3 / G82 M4 Forum (2019+) DCT or Traditional AT?

View Poll Results: DCT or traditional AT?
I prefer a DCT. 168 60.87%
I prefer a traditional AT. 22 7.97%
Either is fine with me. 31 11.23%
I don't care. No manual, no purchase. 55 19.93%
Voters: 276. You may not vote on this poll

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      10-21-2018, 09:08 AM   #1
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DCT or Traditional AT?

Leaving the manual transmission aside, what are potential buyers' opinion on DCT vs a traditional AT?

I personally believe that they should never have killed off the DCT for full fledged M cars, but the media thinks otherwise. It's hardly a secret that the decision to go with the ZF for the F90 M5 is due to the reluctance to develop higher torque rated DCT while the ZF is available off the shelf.
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      10-21-2018, 12:21 PM   #2
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I look at it this way, if the ZF can shift fast enough on the up shifts and react quick enough on the downshifts that there is no material or perceivable difference... why wouldn't I want the better in traffic and around town drivability of the torque converter

I think bmw stated the torque converter on the m5 is fully locked up before the wheels even make one or two revolutions that has to be comparable to a dct slipping the clutch pulling away from a dead stop

Last edited by xlover; 10-21-2018 at 10:31 PM..
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      10-21-2018, 06:43 PM   #3
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DCT is probably better but a well tuned/designed ZF8 is pretty good too. I haven't driven new M5 but if that same tranny comes to M3 I can't imagine they would use it if inferior to DCT.
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      10-22-2018, 12:09 PM   #4
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Quote:
Originally Posted by pheerIx View Post
The ZF will make it feel like every other car out there with the ZF. Every time I try to use manual mode in the ZF I get lazy and just switch it back to auto and go back to sleep. Would rather get a C63 for the V8.
Have you driven many cars with an 8HP transmission? There can be huge differences based on how the transmission is tuned. I've driven relatively poorly tuned 8HP transmissions that pale in comparison to the newest and best tuned 8HP transmissions in newer cars.

I don't drive an automatic, but I don't understand the argument that you go back to driving it in auto mode as if it's a bad thing. If you want to drive it in manual mode, do it. You can drive a DCT in auto mode as well. There's no functional difference between a DCT auto and a planetary auto.
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      10-24-2018, 10:51 AM   #5
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Quote:
Originally Posted by pheerIx View Post
I have the X3 M40i. My point is that the transmission is so good it's actually boring. Pulling paddles all day long provides no entertainment or drama.
I can definitely see that - especially with cars with a lot of torque. You don't have to work the gears, so why bother?

This is part of why automatics used to suck so much. Sure, the transmissions were worse and had fewer gears, but cars were not so torque-rich down low except for big V8's, so people hated automatics when they wanted to keep the revs in a narrower power band to keep the engine responsive and with power - hence why manuals were better.

I've driven sporty cars with decent (admittedly not great) automatics that had manual modes and usually just stuck it in auto mode. As long as the car is torquey and with a decent number of gears, it will drive perfectly fine.

I will buy manuals until they don't sell it anymore. I know soon enough I won't have a choice.
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      10-24-2018, 01:32 PM   #6
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Can somebody explain to me the advantage(if any) to the DCT auto transmission? I've driven for example the ZF 8sp from the Alfa QV and it switches gears like butter and it felt great all the time. I've also heard reviewers say it felt like a DCT at times. I've never driven a DCT because I always choose manual for my cars so that's why I ask.
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      10-25-2018, 04:19 AM   #7
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The 8 speed isnít bad at all it shifts pretty quick and Iím pretty sure the M models are way more tweaked out compared to my plain old 340i. I wouldnít worry much about the DCT going goodbye.
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      10-25-2018, 01:39 PM   #8
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How solidly do the ZF8's torque converters lock while in gear? Im sure there is variation in the tunes for all the various standard/sport/m-sport/m-performance/full-blown-M/etc configurations ( and modes )
When in manual mode will the TC still slip a little when you are on/off/on throttle, whether than be heavy or light throttle. Even if you are in one gear "manually" that wobbly slip that I associate with every normal automatic i have ever driven is annoying. Curious how it will be.
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      10-26-2018, 07:44 AM   #9
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After I swapped the exhaust, the DCT when driving around town was the only part I didn't like about my F80. Especially when you compare it to a Guilia or other similar cars with the ZF, I'm pretty happy that this change is happening.

It's also far cheaper, so hopefully that means they can put the money elsewhere in the G80 to make the overall experience better
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      10-26-2018, 06:00 PM   #10
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I hope its not a DCT cause I absolutely despise mine in the F80. That shit is so jerky and unsmooth, who tf thought this was an acceptable transmission. I'd be so happy if they switched to the ZF.
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      10-27-2018, 12:10 AM   #11
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Quote:
Originally Posted by agentrnge View Post
How solidly do the ZF8's torque converters lock while in gear? Im sure there is variation in the tunes for all the various standard/sport/m-sport/m-performance/full-blown-M/etc configurations ( and modes )
When in manual mode will the TC still slip a little when you are on/off/on throttle, whether than be heavy or light throttle. Even if you are in one gear "manually" that wobbly slip that I associate with every normal automatic i have ever driven is annoying. Curious how it will be.
The TC is basically only open when starting and stopping. In normal driving while the car is moving, the torque converter pretty much stays locked.

When I'm driving my wife's car in Sport+ mode, the shifts are really fast, responsive to manual shift requests, and shifts hard. If you want an automatic, it shouldn't matter whether you get a ZF 8HP or a DCT. It's basically the same thing now.

A lot of the reason supercars use DCTs is because mid-rear engine designs cannot easily fit a torque converted automatic. Even the RS4 and the Alfa Giulia QV use the ZF 8HP. From now on, I doubt you'll be seeing many DCTs on front longitudinally mounted engine cars. There's just no practical reason for it. The ZF 8HP has basically the same performance as a DCT and can transform from a hard shifting sporty transmission to a luxuriously smooth transmission with the touch of a button. It's overall far superior to a DCT.
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      10-27-2018, 10:32 AM   #12
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Quote:
Originally Posted by upsidedownfunnel View Post
The TC is basically only open when starting and stopping. In normal driving while the car is moving, the torque converter pretty much stays locked.

When I'm driving my wife's car in Sport+ mode, the shifts are really fast, responsive to manual shift requests, and shifts hard. If you want an automatic, it shouldn't matter whether you get a ZF 8HP or a DCT. It's basically the same thing now.

A lot of the reason supercars use DCTs is because mid-rear engine designs cannot easily fit a torque converted automatic. Even the RS4 and the Alfa Giulia QV use the ZF 8HP. From now on, I doubt you'll be seeing many DCTs on front longitudinally mounted engine cars. There's just no practical reason for it. The ZF 8HP has basically the same performance as a DCT and can transform from a hard shifting sporty transmission to a luxuriously smooth transmission with the touch of a button. It's overall far superior to a DCT.
I am not sure I want luxurious, smooth feel on an M car. You should get 340i instead for that

Similarly, that's why I love the manual; it comes with twin plate clutch that gives head bang for every upshift you make. Makes the car much more hardcore and sporty.
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      10-27-2018, 03:22 PM   #13
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Quote:
Originally Posted by kyrix1st View Post
I am not sure I want luxurious, smooth feel on an M car. You should get 340i instead for that

Similarly, that's why I love the manual; it comes with twin plate clutch that gives head bang for every upshift you make. Makes the car much more hardcore and sporty.
I drive a manual transmission and I drive it smoothly when I'm warming the car up or when I have my kid in the car. I think many people as they get older appreciate the occasional soft shifting action of a conventional automatic. The ZF 8HP in my wife's car can shift just as hard as a manual. It really bangs out the shifts in Sport+ and Sport shifting mode.
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      12-11-2018, 09:27 AM   #14
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Quote:
Originally Posted by upsidedownfunnel View Post
I drive a manual transmission and I drive it smoothly when I'm warming the car up or when I have my kid in the car. I think many people as they get older appreciate the occasional soft shifting action of a conventional automatic. The ZF 8HP in my wife's car can shift just as hard as a manual. It really bangs out the shifts in Sport+ and Sport shifting mode.
I agree with what you say, but I still think M3 is a wrong car for such.

M3 started out as a homologation race car, and I would like to believe BMW will keep true to its roots. I think they do to some extent looking at M850i launch; they clearly understand general customers are more likely to buy M850i over a full fledged M8, which also started its life as a GT series race car and will translate some of that to its road car.

Besides, cooling a heavy rotating inertia of Zfat is a big problem on track; virtually every M235i I know runs big ass aftermarket coolers to compensate. It sucks when you are on the track/gymkhana in M3 and then Zfat refuses to downshift. I've seen M140i drivers rage because of it on tight circuits after a session or two; IIRC it isn't an issue with DCT. Also, DCT doesn't go flatbed after 7,500 rpm unlike Zfat that hates high rpm.

Then again, more than 70% M drivers who go to track in Japan use 6MT because of simplicity(no need to worry about overheating) and "ultimate driving" experience. Contrary to most beliefs, BMW's twin plate clutch manual transmission is very robust and refined compared to any aftermarket heavy duty multi clutch system that either makes clutch too heavy or clunky at low rpm. On E92 M3, 6MT would actually pull on DCT after 5th gear because it stays longer on the high revs. The surreal experience when you shift at 8400 rpm in 5th going 280+kph to start over at 7200 rpm in 6th is the reason why I think 90s to mid 2000s were BMW's heydays.
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      12-11-2018, 12:48 PM   #15
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My understanding (not an engineer nor even close) is the ZF8 uses the torque converter from a stop and de facto a DCT in operation for changes after that.

There Is a clutch operating anyway.

What's interesting is the new second gen ZF8 opens the clutch during décélération to lower torque and I suppose save gas and wear.

Senna did this bit I think the going logic is most like the car in gear during deceleration
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      12-15-2018, 12:32 AM   #16
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i've got a DCT in my a4, and I have to say its one of the things about the car that I like more than a zf8 (had one in my f30 328i). It just feels more direct even in a normal car. I don't think the zf8 will be bad at all, but its not a DCT in the end.

ON the plus side, dual clutch maintenance is more than automatic for long term
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      01-04-2019, 12:43 AM   #17
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Regardless of what technology an AT uses (DCT vs "traditional" torque converter planetary gears) I want a transmission that shifts smoothly. While a rough shifting AT may give the illusion of a "sports car" I am not interested in an AT that emulates a poorly driven MT. Rough or harsh shifts may give the illusion of performance but in reality speed is about smoothness and harsh or jerky shifts upset the balance of the car.
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      01-14-2019, 04:35 PM   #18
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Quote:
Originally Posted by SleepingBMW View Post
My understanding (not an engineer nor even close) is the ZF8 uses the torque converter from a stop and de facto a DCT in operation for changes after that.

There Is a clutch operating anyway.

What's interesting is the new second gen ZF8 opens the clutch during décélération to lower torque and I suppose save gas and wear.

Senna did this bit I think the going logic is most like the car in gear during deceleration

The torque converter on the ZF 8 Speed is locked up once the car is in motion. It is, however, a planetary gear transmission and the technology doing the shifts is quite different than a DCT. Both The ZF 8 Speed and the DCT are capable of very fast and very smooth shifts.





From what I found by Googling the ZF 8 speed shifts gears an about 200 milliseconds while the DCT shifts gears in about 100 milliseconds. When comparing these shift speeds keep in mind that the blink of an eye is about 300 milliseconds.
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Last edited by captainaudio; 01-14-2019 at 04:45 PM..
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      01-14-2019, 07:37 PM   #19
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DCT shifts faster than the ZF 8 if it correctly predicts the next gear and just has to engage the clutch, but it may guess poorly and have to adjust. Smarts in both transmissions are key.
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      02-08-2019, 08:36 AM   #20
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Problem with most DCTs nowadays (for front engines) is that they have no room to grow and can't handle as much torque as the good torque converters.
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      02-09-2019, 05:30 PM   #21
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Quote:
Originally Posted by reyoasian View Post
Problem with most DCTs nowadays (for front engines) is that they have no room to grow and can't handle as much torque as the good torque converters.
Sure but in the previous M5 and M6 the DCT had 700nm. I really can't see that the new M3 will have anywhere near that.
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      02-11-2019, 01:52 AM   #22
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Quote:
Originally Posted by reyoasian View Post
Problem with most DCTs nowadays (for front engines) is that they have no room to grow and can't handle as much torque as the good torque converters.
812 Superfast has 720Nm of max torque(revs to 8500 rpm) and uses the same good old Getrag 7 speed DCT from 458 with some modifications. Panamera uses ZF 8 speed DCT rated at 1000Nm for both RWD and AWD configurations. Even if in unlikely case that G80 M3 is rated around 700Nm, I don't buy the torque logic.

Gotta say though, with Van Meel moving up to the total vehicle development department, we'll see more of AWD based chassis.. eventually all BMWs will be AWD for better driveability and more complexity. Heydays of 3 year lease BMWs.

Good thing BMW is creating pure version, but engineers should aspire to be more creative when they are releasing a new model- not just some high-end tuner level turbocharging and DME mapping seen on F90.
Can't help but think that BMW M these days went from a completely distinguished car from production 3 series to a tuned up 340i. They try to appeal driving dynamics with simple interior and ergonomics yet let go of making unique transmissions and engines.
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