[jmg]

Such a great piece of engineering that will be missed in the G80.

[///My5UV]

Originally Posted by jmg

Such a great piece of engineering that will be missed in the G80.

Is that something you know, or just suspect?

I think they dropped DCT from the M5 due to the much higher torque of the turbo 8, but I'd guess the F10 DCT could handle anything a turbo 6 puts out.

[jmg]

Originally Posted by ///My5UV

Is that something you know, or just suspect?

I think they dropped DCT from the M5 due to the much higher torque of the turbo 8, but I'd guess the F10 DCT could handle anything a turbo 6 puts out.

It's the rumor.

[CanAutM3]

Originally Posted by ///My5UV

Is that something you know, or just suspect?

I think they dropped DCT from the M5 due to the much higher torque of the turbo 8, but I'd guess the F10 DCT could handle anything a turbo 6 puts out.

The DCT in the F1X M5/6 is the same unit used in the F8X M2/3/4 and is rated up to 700N-m of torque.

[CanAutM3]

Originally Posted by jmg

It's the rumor.

I have a hunch that the next gen M2/3/4 will retain DCT. The S58 will have nowhere near the 700N-m of max torque. I also doubt that the next gen M3/4 will be getting AWD. So an evolution of the current DCT would still be a great match for the next gen M2/3/4.

IMO, the main reason BMW went with the 8AT on the M5 is for cost. They did not want to invest in the development of a longitudinal DCT with a higher torque rating and compatible with AWD when they had something available off the shelf with these capabilities in the ZF 8AT. Further, due to the car's heft and AWD, the advantages of a DCT might not be as prevalent on the M5. There are DCT that can handle higher torque (Chiron: 1180 lb-ft, Ferrari 488GTB: 561ft-lb, 911 Turbo-s: 553lb-ft just to name a few). So IMO, it is not the inability for the DCT concept to handle the M5's torque, but it is rather that no "off the shelf" option was available to fit the M5 application that drove the decision.

[mkoesel]

Originally Posted by CanAutM3

IMO, the main reason BMW went with the 8AT on the M5 is for cost.

I agree. It always comes back to cost.

I also agree with the points you make. One other thing to keep in mind is that the S58 will be shared with other M products this time around - namely the X3 M and X4 M. I think we can all agree that the DCT is unlikely there given the AT in the X5 M and X6 M. Even Porsche does not use a DCT in their high performance SUVs.

While it’s true that M division used the DCT in the last M5 and M6 even though they could have moved to the ZF AT then, and it’s also true that the move to AWD for the M5 probably allowed them to save more cost than otherwise given that they already had something similar developed for the afore mentioned M SUVs, I think that, even if they stay RWD, the next M3 and M4 are likely to move to the ZF. The reasons I think so are that we are in a lower price bracket with lower margins so costs are even more controlled, key competitors - the RS5 and upcoming RS5 Sportback - have switched to the AT, and performance (if not quite feel, perhaps) of the AT has essentially caught up with the DCT.

Just my take.

[CanAutM3]

Originally Posted by mkoesel

Even Porsche does not use a DCT in their high performance SUVs.

What about the Macan turbo ?

But I agree, a DCT is unlikely in the X3/4M because of the AWD.

Originally Posted by mkoesel

I think that, even if they stay RWD, the next M3 and M4 are likely to move to the ZF. The reasons I think so are that we are in a lower price bracket with lower margins so costs are even more controlled, key competitors - the RS5 and upcoming RS5 Sportback - have switched to the AT, and performance (if not quite feel, perhaps) of the AT has essentially caught up with the DCT.

Just my take.

Well, if the M2/3/4 remain RWD there wouldn't be much development cost to maintain the DCT. And I disagree, having test driven a S4, RS5 and C63S, the AT has not yet quite caught up to DCT. ATs are heavier, have more rotating mass and more drivetrain loss than DCTs. There is a sharpness and drivetrain response that just isn't there.

[mkoesel]

Originally Posted by CanAutM3

What about the Macan turbo ?

But I agree, a DCT is unlikely in the X3/4M because of the AWD.

My mistake - I thought that they were already using the same transmissions in the Macan as they do in the Cayenne. So, as far as SUVs go, that's an outlier for now. As the Panamera and Cayenne have in their latest incarnations, it appears they are going to switch to the standard VAG V6 engines - the 3.0L single turbo and 2.9L twin turbo - for the Macan LCI rumored for this year. So it will be interesting to see if they continue to use the PDK or if they switch to the AT. The Cayenne uses the AT while Panamera sticks with the PDK. All Audi applications will use the AT.

Well, if the M2/3/4 remain RWD there wouldn't be much development cost to maintain the DCT.

Relatively speaking, sure, that could be the case. But there are still other factors like simplifying the supply chain and manufacturing processes.

The decision on whether to keep the 6MT may also play a role because you have the opportunity to go from what would now be three transmissions to just one instead. On the other hand, they could at least keep the count at two by eliminating either one or the other of the existing ones used with the S55, and maybe the DCT stands the better chance to make the cut in that case. Though the M2 market might say different. Tough to guess. To me though, if the 6MT goes, the opportunity to cut that not just to two but down to one seems like a tempting proposition if I put myself in the shoes of those counting the beans.

And I disagree, having test driven a S4, RS5 and C63S, the AT has not yet quite caught up to DCT. There is a sharpness and drivetrain response that just isn't there.

I wouldn't disagree with your opinion - like I say, there may very well still be a difference in feel. But, from the business side of things, on paper they may not show enough separation to justify the extra cost anymore.

[swifty]

The ZF tranny hasn't caught up to DCT no matter what the shift times are. You can feel the difference when you drive them.

Nevertheless it's good to see that BMW implementing DCTs into the Mini brand even though it's a lower premium car.

I agree, financially and technically speaking it didn't make sense for BMW to spend that type of time & resources on the M5 with AWD when they could use same tranny from X5M. Also the demographic they are trying to reach with the new M5 is slightly different from years past.

However one thing that caught my attention recently is the new Bentley is using a DCT instead of automatic.

[mkoesel]

Originally Posted by swifty

Nevertheless it's good to see that BMW implementing DCTs into the Mini brand even though it's a lower premium car.

Like other manufacturers, they appear to be doing this because there are efficiency gains to be realized and because cost is not as big a tradeoff vs. the AT in lower power (and thus lower torque) applications. Note that the Clubman, Countryman, and JCW models will use the AT. Here's the plan:

http://www.motoringfile.com/2017/12/...fficial-debut/

BMW has also begun using the DCT for some UKL BMW models. So far I think it is just for FWD models. As with MINI, they may very well choose not to use the DCT for AWD models.

However one thing that caught my attention recently is the new Bentley is using a DCT instead of automatic.

Probably borrowed from the Panamera since they share the same MSB platform.

[boosted43]

I think the move to a ZF 8 Speed was a good call. After driving both and M5 and Alpina B5 I personally liked the Alpina much better, it was easier to live with in stop and go traffic than the DCT. Not saying the DCT is bad in traffic but the Alpina was a lot smoother shifting than the M5, but a little slower.

[jmg]

Originally Posted by kabawi91

I think the move to a ZF 8 Speed was a good call. After driving both and M5 and Alpina B5 I personally liked the Alpina much better, it was easier to live with in stop and go traffic than the DCT. Not saying the DCT is bad in traffic but the Alpina was a lot smoother shifting than the M5, but a little slower.

That's fine if you live to be in traffic, but I don't drive an M or any other high performance car to be comfortable in traffic. I drive one to enjoy the way it drives fast.

[boosted43]

Originally Posted by jmg

That's fine if you live to be in traffic, but I don't drive an M or any other high performance car to be comfortable in traffic. I drive one to enjoy the way it drives fast.

No one drives a car to be in traffic that sounds stupid. Simply stating an opinion that a ZF 8 Speed suits the M5 better than a DCT considering it's a luxury sedan that's also capable of being driven like a super car.

[jmg]

Originally Posted by kabawi91

No one drives a car to be in traffic that sounds stupid. Simply stating an opinion that a ZF 8 Speed suits the M5 better than a DCT considering it's a luxury sedan that's also capable of being driven like a super car.

I think a lot of people would disagree.. then again I haven't driven the new M5 so maybe you are right. I just never found the DCT to be at all cumbersome in traffic, especially in efficient mode, which I rarely use lol. Sport mode is just fine.

[boosted43]

Originally Posted by jmg

I think a lot of people would disagree.. then again I haven't driven the new M5 so maybe you are right. I just never found the DCT to be at all cumbersome in traffic, especially in efficient mode, which I rarely use lol. Sport mode is just fine.

For me personally it was a bit jerky and shifts weren't as smooth as the ZF 8 Speed. I don't understand why all the negativity towards the Auto. I don't think it'll make a huge difference in shift times

[jmg]

Originally Posted by kabawi91

For me personally it was a bit jerky and shifts weren't as smooth as the ZF 8 Speed. I don't understand why all the negativity towards the Auto. I don't think it'll make a huge difference in shift times

I think it's the overall experience. I had two F30s both with the ZF8 and I found the DCT much much more fun and responsive.

[CanAutM3]

Originally Posted by kabawi91

For me personally it was a bit jerky and shifts weren't as smooth as the ZF 8 Speed. I don't understand why all the negativity towards the Auto. I don't think it'll make a huge difference in shift times

When talking DCT, "shift time" is a bit irrelevent. The "shift time" is the time it takes for the power path to shift from one clutch to the other. However, since power continues to be transmitted to the drive wheels during the shift, the time it takes does not really affect performance. It's not like the shift time on an MT or SMG, where the flow of power to the drive wheels is interrupted while the clutch is dissengaged, the gear is shifted and the clutch is re-engaged.

When comparing an AT to DCT, it is more a question of overall efficiency. A planetary AT has much more rotating mass than a DCT, which makes the drivetrain more sluggish and less responsive. Further, the secondary clutches that lock the planetary sets for the different gear selection in a traditional AT are not as stout as the main DCT clutches, so the engine power needs to be momentarily cut back during the shift. The DCT clutches can handle an all out WOT power shift to fully recuperate the engine inertia, which makes it slightly more efficient on acceleration. Traditional AT also have more loss and are heavier than DCT. There is a reason why the top end sports cars use DCT.

[Alpine300zhp]

Originally Posted by jmg

That's fine if you live to be in traffic, but I don't drive an M or any other high performance car to be comfortable in traffic. I drive one to enjoy the way it drives fast.

Exactly. If one slogs through heavy traffic on a regular basis, the M is not really the best choice. When I lived in the DC metro area, I tried an M car and hated it. In sunny South Florida, the M's are my favorite automobile.

[uniqueMR]

Originally Posted by CanAutM3

When talking DCT, "shift time" is a bit irrelevent. The "shift time" is the time it takes for the power path to shift from one clutch to the other. However, since power continues to be transmitted to the drive wheels during the shift, the time it takes does not really affect performance. It's not like the shift time on an MT or SMG, where the flow of power to the drive wheels is interrupted while the clutch is dissengaged, the gear is shifted and the clutch is re-engaged.

When comparing an AT to DCT, it is more a question of overall efficiency. A planetary AT has much more rotating mass than a DCT, which makes the drivetrain more sliggish and less responsive. Further, the secondary clutches that lock the planetary sets for the different gear selection in a traditional AT are not as stout as the main DCT clutches, so the engine power needs to be momentarily cut back during the shift. The DCT clutches can handle an all out WOT power shift to fully recuperate the engine inertia, which makes it slightly more efficient on acceleration. Traditional AT also have more loss and are heavier than DCT. There is a reason why the top end sports cars use DCT.

Well said

[Eddien123]

I'm going to guess it'll be the 8AT. Bmw clearly has their profits set to the highest priority. It will be much cheaper to use the 8AT than to do a 3rd generation DCT when the 8AT is already developed in a form that can handle the power the new M3/4's power.

[Wills2]

Originally Posted by Eddien123

I'm going to guess it'll be the 8AT. Bmw clearly has their profits set to the highest priority. It will be much cheaper to use the 8AT than to do a 3rd generation DCT when the 8AT is already developed in a form that can handle the power the new M3/4's power.

The current DCT can handle 600hp (as seen in the F10 M5) the new M3 won't have more than that it'll have considerably less.

[Eddien123]

Originally Posted by Wills2

The current DCT can handle 600hp (as seen in the F10 M5) the new M3 won't have more than that it'll have considerably less.

Not with awd. The main reason the dct was dropped from the f90 was the awd system. And the next M3/4 will most likely have it as well. I wasn't saying the dct can't handle it I'm saying the 8AT is already produced in a form that can handle whatever power it'll make so there's no need for them to go back and modify it and spend money on R&D. It's already done and ready