[fanshu]

I am not sure if anyone covered this, I was wondering why a lot of people now said car manufacturers are using back traditional auto gearbox due to DCT can't handle bigger torque.

Yes, you can see Audi is using ZF 8-speed for their new S4/S5 and also in RS6/RS7.

But I wonder why Porsche is using their PDK dual clutch gearbox for all their cars, even 911 turbo S which definitely got huge torque.

Is the new M5 x-drive are still using DCT?

[zenmaster]

http://f87.bimmerpost.com/forums/sho....php?t=1376991

I don't think torque handling is the issue. Rather, cost, weight, shift speed and economy for auto will eventually beat DCT.

[SeanWRT]

Originally Posted by zenmaster

http://f87.bimmerpost.com/forums/sho....php?t=1376991

I don't think torque handling is the issue. Rather, cost, weight, shift speed and economy for auto will eventually beat DCT.

Cost is the only reason, don't let anyone tell you otherwise.

[MagnusT]

And weight.

[zenmaster]

Originally Posted by SeanWRT

Cost is the only reason, don't let anyone tell you otherwise.

Lol. Who needs people to tell them? All the stats are objectively measurable. Cost is NOT the only reason of course, because this tech is put into performance cars which already carry a premium - not their bread and butter vehicles. BMW still needs to compete on performance.

[fanshu]

IC
thanks

[DivideBYZero]

Originally Posted by MagnusT

And weight.

Got specs for DCT Vs ZF8 weight? Interested, as I have both in my fleet.

[tstafford]

I'm not an engineer but there is no way someone could convince me that any automatic could shift faster than Porsche's PDK-S. The GT3 RS is telepathic in it's shifts - always, always where it should be and can move b/w gears so fast it's seamless.

[DivideBYZero]

Originally Posted by MagnusT

And weight.

Nope.

ZF8 - 87Kg
https://www.zf.com/corporate/en_de/p...smission.shtml

M-DCT - 78-82Kg
http://www.getrag.com/en/products/po...smissions.html

[XutvJet]

Originally Posted by tstafford

I'm not an engineer but there is no way someone could convince me that any automatic could shift faster than Porsche's PDK-S. The GT3 RS is telepathic in it's shifts - always, always where it should be and can move b/w gears so fast it's seamless.

BMW has stated that they will be ending the DCT in the next few years and will be only be using planetary autos. My guess is they'll start using the multi clutch pack systems in place of the torque converters like what Benz is currently using in some of their high performance cars. These multi clutch pack systems are much lighter than a heavy, fluid-filled torque converter and offer up even quicker up and downshifts.

[akkando]

Originally Posted by XutvJet

BMW has stated that they will be ending the DCT in the next few years and will be only be using planetary autos. My guess is they'll start using the multi clutch pack systems in place of the torque converters like what Benz is currently using in some of their high performance cars. These multi clutch pack systems are much lighter than a heavy, fluid-filled torque converter and offer up even quicker up and downshifts.

The upcoming M5 uses this I believe.

[zenmaster]

Originally Posted by DivideBYZero

Nope.

ZF8 - 87Kg
https://www.zf.com/corporate/en_de/p...smission.shtml

M-DCT - 78-82Kg
http://www.getrag.com/en/products/po...smissions.html

No one was talking about or implying current tech, but rather future tech in the industry. "Writing on the wall".

[DivideBYZero]

Originally Posted by zenmaster

No one was talking about or implying current tech, but rather future tech in the industry. "Writing on the wall".

OP clearly states the "current future state" of the ZF8 as it is supplied in the new RS5. That's why I took the direct comparison.

[chris719]

GT2 RS makes 700 HP and 553 lb-ft of torque and uses a dual clutch gearbox. Many modified Nissan GT-Rs are making huge power on DCT gearboxes (with upgraded clutch packs).

It's purely a cost move. Maybe also the fact that DCT is not quite as refined as a ZF auto box from a stop.

Just like that nonsense from Frank van Meel about the manual transmissions not handling the torque. C7 Z06 makes 650 lb-ft of torque through a Tremec MT that, generally speaking, is regarded as shifting better than BMWs long throw sloppy MTs. There will not be an M3/M4 approaching that figure for a long time, if ever.

Again, they probably mean cheaply.

Journalists have low standards. The Giulia QV and other BMW competitors have had these lazy, sloppy, high latency (from paddle pull) shifting transmissions and barely get penalized in reviews for them. I just watched a C7 Grand Sport review video and you could hear the delay between the click and the shift. BMW must feel like they are spending the money for no reason. Plus then they get the soccer mom complaints about no creeping or the way the transmission engages when you roll onto the throttle...