[Hoiser]

The biggest difference from my DCT in the M4 to a 2020 m550i is the 8AT. It is completely lazy and is the biggest let down in the car. Gear changes are gummy and not direct.

[ashtaron14]

Journalists:
F8x M3 - DCT isn't good around town
G8x M3 - ZF8 lacks drama of the DCT

So BMW should not listen.

I find the ZF8 in the M340i quite okay. Brake late, hold the down-gear paddle and the car will automatically go into the lowest gear allowed at that speed. Being able to skip a gear reduces time. I think the ZF8 is plenty fast.

[Encanto]

M-DCT is the best of both worlds - manual shifting without a foot clutch, and adjustable automatic shifting when desired.

M-DCT was the last M feature of the M3/M4. What is left is a faster, wider, and pricier M340i.

[brad850csi]

I've done 50k miles in my M6 which is driven every day in town. There is absolutely no problems with using it in town at all apart from it being easiest/smoothest/best to use your left foot on the brake when doing a 3 point turn on a slope to keep the car stationary when going from reverse to first or vice versa.

I agree there is a bit of a learning curve but it is an utterly fantastic box.

I'm going to do a track day with my car and the entire current range of M cars on Thursday and I'm looking for the electronic power steering and gearbox feel in particular. I've driven an M8 and the steering actually annoyed me more than the gearbox, we'll see what the M3/M4 is like.

[VIERsr]

AFAIK, the main reason to switch to the ZF8 is because of the 4WD system, Xdrive is not compatible with DCT (or maybe it would have involved too much work to adapt while the ZF8 was already ready).

[M6-Coupe]

Originally Posted by Cmassey3

So fastest shift is 150ms? What ms were the previous 2(E9x/F8x) DCT units doing?

BMW MDCT was 80 ms

[VIERsr]

Originally Posted by M6-Coupe

BMW MDCT was 80 ms

I wouldn't pay too much attention to these times, Bmw also claimed 80ms for the SMG2 on the M3 E46 and 60ms for the SMG3 on the E60, but we all know how slow they are compared to the DCT.
On transmissions with robotized shifting (with single or double clutch) there are 3 phases (input, disengaging and re-engaging the gear), 80ms is the proper shift time, but you have to consider the delay from your input on the paddle and the full shift. The whole process is longer than the claimed shift time. In fact, the complete shifting time for the SMG was around 2/300ms, much less on DCT.

[M6-Coupe]

Originally Posted by jonahk

This was my first thought during my test drive, I really REALLY liked the "dynamic-ness" (ugh, too many review videos lately) of the DCT but after 30 minutes I feel like I had the ZF8 figured out. It's nowhere near as exciting, but I kinda forgot about that once I felt how fast the car went from 60-100...

Would love to hear some other reviews from current G80 owners that came from the F8x cars with DCT. Do you miss it?

My F13 M6 had DCT and my F92 M8 has ZF.
And yes I miss DCT when I want to drive like crazy but in comfort mode ZF is so smooth.
ZF doesn't have the jerkiness of DCT and that "kick" and you feel the gear change is slower but still the total drivetrain( engine+ tranny+LSD) is fun ... of course not as fun as my F82/F80 cp with 6 speed manual transmission

[M6-Coupe]

Originally Posted by VIERsr

I wouldn't pay too much attention to these times, Bmw also claimed 80ms for the SMG2 on the M3 E46 and 60ms for the SMG3 on the E60, but we all know how slow they are compared to the DCT.
On transmissions with robotized shifting (with single or double clutch) there are 3 phases (input, disengaging and re-engaging the gear), 80ms is the proper shift time, but you have to consider the delay from your input on the paddle and the full shift. The whole process is longer than the claimed shift time. In fact, the complete shifting time for the SMG was around 2/300ms, much less on DCT.

Well 80 ms or 100 ms should feel the same because human brain is not that fast to recognize 20 ms difference but since I have both experience , can claim DCT is obviously faster than ZF

[VIERsr]

Originally Posted by M6-Coupe

Well 80 ms or 100 ms should feel the same because human brain is not that fast to recognize 20 ms difference but since I have both experience , can claim DCT is obviously faster than ZF

There is no doubt
But the shifting times don't describe the whole shifting process, that's why DCT is much faster than SMG despite the same claimed shifting time (80/100ms).

[Aus335iguy]

When looking at dct logs on a 335i with the fastest calibration we have available(e92m3 GTS) the total amount of time that the torque reduction is in effect is 90ms. This the total shift time excluding delay from users hand to the time the actual shift is initiated and torque starts getting reduced. In a ZF as stated this time is 150ms. Yes you can feel the difference and anyone who's says the ZF is faster needs to look at the facts.
The reason some shifts in a dct seem like an eternity is because it's actually two gearboxes and your not usually shifting gears but gearboxes
1,3,5 and 7 in one box 2,4,6 and r in the other.
The gearbox when in first has the second box in second gear on standby and simply drops the clutch on that box when you want to shift. If you double click and go 1st to 3 rd, you can see it's a single gearbox shift has to go from first... to neutral and then 3rd and therefore takes longer.

The ZF is more refined because it's easier to refine. It'll be more consistent, easier to launch, cheaper to produce and cheaper to service

If you want to race though....it's not even a contest really.

[thaalrasha]

I think DCT is superior and some manufacturer could make DCT work with AWD, however probably the development cost was too high. That's partially why Albert Biermann left BMW after so long when the development of F90 M5's DCT was cancelled (read this in an interview somewhere).

ZF is fast enough but removes the drama... Ideally the DCT should be also tuned well enough to allow smooth low speed operation (it's clearly not impossible, maybe can't be a smooth but still) and at the same time have an agressive setting when desired.

I don't buy M cars to have the fastest car around the track, it's mostly because of the fun / engaging driving experience and the drama is part of that in M cars.

Then again it might have been the right move ... what's the competition ? a hybrid 4 pot C63 ? a grown up understeering RS4 ? a 2 seater Porsche ? ... yeah ...

[CanAutM3]

Originally Posted by VIERsr

AFAIK, the main reason to switch to the ZF8 is because of the 4WD system, Xdrive is not compatible with DCT (or maybe it would have involved too much work to adapt while the ZF8 was already ready).

^ This

They could have worked on the development of a new DCT compatible with AWD, but IMO decided it was not worth the investment.

[gmd2003]

Originally Posted by CanAutM3

^ This

They could have worked on the development of a new DCT compatible with AWD, but IMO decided it was not worth the investment.

The AWD, high HP,high Tq ,DCT gearboxes already exist they just didn't want to pay for them end of story . It's sad that Ford and GM started using DCT's on their cheaper sport vehicles when BMW stopped . I'm not giving them a pass on this one .

[Scorp!on]

Originally Posted by CanAutM3

^ This

They could have worked on the development of a new DCT compatible with AWD, but IMO decided it was not worth the investment.

Exactly what I think.

Never forget:
In the end BMW is a Business like ever other Business too.
Their main goal is to earn money.

I guess they did the calculation and found in long term it will be cheaper to go with the ZF8. The other solution would have been to develop the DCT and invest ton of money which then the costumer would have to pay in a way.
So the car would have been more expensive, and they already are far away from cheap...

[CanAutM3]

Originally Posted by VIERsr

I wouldn't pay too much attention to these times, Bmw also claimed 80ms for the SMG2 on the M3 E46 and 60ms for the SMG3 on the E60, but we all know how slow they are compared to the DCT.
On transmissions with robotized shifting (with single or double clutch) there are 3 phases (input, disengaging and re-engaging the gear), 80ms is the proper shift time, but you have to consider the delay from your input on the paddle and the full shift. The whole process is longer than the claimed shift time. In fact, the complete shifting time for the SMG was around 2/300ms, much less on DCT.

The shift time in itself does not mean much, what matters is what happens during those precious milliseconds.

I posted this elsewhere previously but I will repeat here because I believe it is pertinent.:

On the single clutch SMG, the clutch needs to disengage while the transmission changes gear before it can be re-engaged, therefore there's an actual period of deceleration during the upshift while the clutch is disengaged and no power is being transmitted to the drive wheels. This also causes serious chassis disruptions and SMG cannot be shifted during at limit cornering. So no real performance benefit vs a standard manual except that it is automated (driver can focus more on driving).

With a dual clutch DCT, the next higher gear is already engaged, so you have one clutch slipping against the other as the flow of power is passed from one to the other, so there is no interruption of acceleration during the shift. Furthermore, since the DCT clutches are used to launch the car from rest, they need to be very robust. This means they can handle an all out WOT power shift, which allows to recuperate the inertia from the engine RPM drop and provide a boost of acceleration. So the DCT can actually increase acceleration during the upshift (the "jolt" many people refer to). The DCT can also execute butter smooth upshifts to avoid upsetting the chassis during cornering.

Planetary automatics like the ZF8 in performance application can keep the torque converter locked up once rolling and transfer the power by slipping the planetary clutch packs agains each other to change gears, similar to a DCT. However, the planetary clutch packs are not as robust as the main DCT clutches and cannot handle an all out power shift. This means that the engine power needs to be momentarily reduced during the upshift. So while the ZF8 can still shift gears without interrupting the flow of power, there is a momentary decrease in acceleration during the upshift. To me, that is the key differentiation that makes the ZF8 less engaging to drive than the DCT. I'd say the biggest performance advantage of the ZF8 is the ability to use the torque multiplication and torque braking to increase boost when launching from rest. This is not really an advantage on a RWD car (as demonstrated with the RWD G8X using 2nd gear for launch control), but will definitely help rocket the G8X AWD out of the gate in 1st gear.

This is all in line with what the ///M engineer describes in the video.

[CanAutM3]

Originally Posted by gmd2003

The AWD, high HP,high Tq ,DCT gearboxes already exist they just didn't want to pay for them end of story . It's sad that Ford and GM started using DCT's on their cheaper sport vehicles when BMW stopped . I'm not giving them a pass on this one .

I'm with you. The demise of the DCT is one of the key factors for me jumping ship.

[VIERsr]

Originally Posted by CanAutM3

The shift time in itself does not mean much, what matters is what happens during those precious milliseconds.

I posted this elsewhere previously but I will repeat here because I believe it is pertinent.:

On the single clutch SMG, the clutch needs to disengage while the transmission changes gear before it can be re-engaged, therefore there's an actual period of deceleration during the upshift while clutch is disengaged. So no real performance benefit vs a standard manual except that it is automated (driver can focus more on driving).

With a dual clutch DCT, the next higher gear is already engaged, so you have one clutch slipping against the other as the flow of power is passed from one to the other, so there is no interruption of acceleration during the shift. Furthermore, since the DCT clutches are used to launch the car from rest, they need to be very robust. This means they can handle an all out WOT power shift, which allows to recuperate the inertia from the engine RPM drop and provide a boost of acceleration. So the DCT can actually increase acceleration during the upshift (the "jolt" many people refer to). The DCT can also execute butter smooth upshifts to avoid upsetting the chassis during cornering.

Planetary automatics like the ZF8 in performance application can keep the torque converter locked up once rolling and transfer the power by slipping the planetary clutch packs agains each other to change gears, similar to a DCT. However, the planetary clutch packs are not as robust as the main DCT clutches and cannot handle an all out power shift. This means that the engine power needs to be momentarily reduced during the upshift. So while the ZF8 can still shift gears without interrupting the flow of power, there is a momentary decrease in acceleration during the upshift. To me, that is the key differentiation that makes the ZF8 less engaging to drive than the DCT. I'd say the biggest performance advantage of the ZF8 is the ability to use the torque multiplication and torque braking to increase boost when launching from rest. This is not really an advantage on a RWD car (as demonstrated with the RWD G8X using 2nd gear for launch control), but will definitely help rocket the G8X AWD out of the gate in 1st gear.

This is all in line with what the ///M engineer describes in the video.

I just wanted to clarify that 'that' 80ms doesn't mean anything as it is the same time claimed for both SMG and DCT, but far from the real time shift for the reasons mentioned above.
The ZF8 is totally another kind of transmission.

[CanAutM3]

Originally Posted by VIERsr

I just wanted to clarify that 'that' 80ms doesn't mean anything as it is the same time claimed for both SMG and DCT, but far from the real time shift for the reasons mentioned above.
The ZF8 is totally another kind of transmission.

I replied to your post, but my post was intended as general information for the thread and not directly aimed at you specifically. Sorry for the confusion.

[somer]

Originally Posted by CanAutM3

I'm with you. The demise of the DCT is one of the key factors for me jumping ship.

Same.

[XsltAnalyst]

Originally Posted by gmd2003

The AWD, high HP,high Tq ,DCT gearboxes already exist they just didn't want to pay for them end of story . It's sad that Ford and GM started using DCT's on their cheaper sport vehicles when BMW stopped . I'm not giving them a pass on this one .

M3 has been getting hand me downs from M5 (DCT, rear diff, etc) in previous generations so it doesn't make sense for them to R&D new AWD DCT for a cheaper model.
It works fine in M5 so I don't think it'll be an issue for majority of the people.

Besides, who knows what the reliability of a new DCT would've been.
ZF8 or DCT may not even be used in next gen if we believe what's to come based on new C63 (4 cyl with 2 speed gearbox/ electric motor)

We should be glad bmw still offers MT since no other cars in this class offers one.

[CanAutM3]

Originally Posted by XsltAnalyst

M3 has been getting hand me downs from M5 (DCT, rear diff, etc) in previous generations so it doesn't make sense for them to R&D new AWD DCT for a cheaper model.

Besides, who knows what the reliability of a new DCT would've been.
ZF8 or DCT may not even be used in next gen if we believe what's to come based on new C63 (4 cyl with 2 speed gearbox/ electric motor

We should be glad bmw still offers MT since no other cars in this class offers one.

The DCT in the E9X M3 was specifically developed for this application (was later shared with other models). The SMG I was specifically developed for the E36, SMG II for the E46 and SMG III for the E60. Bespoke gearbox development for specific chassis applications was not uncommon in the ///M of yore.

And yes, kudos to BMW to keep offering MT in this segment.