08-01-2013, 12:37 PM | #1 |
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ZF vs DCT in new M3/M4
For the more knowledgable out there. I have read some great reviews on the new 8 speed ZF tranny in vehicles in excess of 400 HP and comparable torque. The extra gearing improves fuel estimates and I have seen great comments on shift speeds being almost imperceptible. Wouldn't it be prudent for BMW to use this in the upcoming M vs the 7 speed DCT? Is there an advantage to the DCT? Anyone in the please let me know.
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08-01-2013, 12:47 PM | #2 |
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I had the ZF in my F10. It shifts pretty fast but this is still a slush box and shifting manually feels just as meaningless and uninspiring as any slush box. The DCT is faster but it's main advantage for me is that it actually feels natural and inspiring to shift manually and I don't think the ZF is capable of the glorious throttle blips with the Getrag DCT. Sad thing is I haven't heard any of those blips from the F8X videos
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08-01-2013, 12:48 PM | #3 |
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For right now, my understanding is that the DCT still offers the better experience for high performance driving situations.
As far as fuel efficiency, I don't think there is a vehicle that offers a seven speed DCT and an eight speed planetary box, so it would be difficult to get an apples to apples comparison. Generally, DCT's have gained popularity lately due to being more efficient than a slush box. However there are many variables that could tip that the other way. |
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08-01-2013, 01:05 PM | #4 |
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The ZF 8 speed still has a torque converter, which is the main contributor to the "disconnected" feel of traditional automatic gearboxes. From my perspective, I feel the same connection from the engine to the wheels in a DCT compared to a standard manual. This makes sporty driving much more enjoyable.
The counterpoint is that the "disconect", through the viscous fluid in the torque converter, also contributes to make an "automatic" transmission much smoother in operation compared to DCT. Better fuel economy could be achieved by making the 7th gear in the DCT much longer while keeping the ratio from 1 to 6 closely spaced. Who uses 7th at the track anyway . |
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08-01-2013, 02:23 PM | #5 |
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One thing for sure, an Auto has never been so close to a DCT as it is today with the ZF8.
To answer the question.......drive a C63 AMG. It is fitted with the Mercedes 7G Tronic auto, but with torque converter clutch over ride (similar to ZF8). I would definitely say the ZF8 is even Sportier than the Mercedes auto, as it locks up in every gear from 30mph, so has a 'manual - direct' type feel, and has quicker shift speeds. Anyway, although the C63 box is OK, it just isn't as Sporty as the DCT. ZF8 will be closer to DCT, and almost unnoticeable on upshifts, but downshifts are always going to be 'blends' rather than real cog swapping IMO. |
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08-01-2013, 03:17 PM | #7 | |
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Automatics are progressing just like DCTs are. I'd say that automatics have actually progressed more than DCTs in the last 5 years. The full locking feature of new high end automatics has substantially helped both feel (more like MT/DCT) and efficiency. That being said I give a small edge to the DCT for both feel and efficiency.
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08-01-2013, 06:35 PM | #8 | |
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08-01-2013, 08:49 PM | #9 |
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I can attest to the multi-clutch automatic in my C63 Black Series. It sure feels crazy close to a DCT to me, and I'm quite impressed with how far automatics have come. I do agree that it's still not a DCT (and that's part of why you see the DCT in the SLS, SLS GT, and SLS Black Series).
Here's a (slightly cheesy, but still mildly informative) video about the AMG MCT transmission: Last edited by GreenLantern; 08-01-2013 at 09:40 PM.. |
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08-03-2013, 01:00 PM | #10 |
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I drove 400 miles in a new 550i with the ZF. Not impressed at all. Sure its smooth, but felt like a grandmother car. I much prefer the DCT it's the second best thing to a manual at the moment. The reason to go for the 335is or M3/4/5/6 otherwise just get the manual.
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08-10-2013, 04:55 PM | #13 |
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08-10-2013, 05:10 PM | #14 |
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08-10-2013, 05:42 PM | #15 |
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I currently own a 6 speed manual in my GTI. My Porsche has an 8 speed automatic. I have had a ton of manuals and nothing is as fast as the DCT in my previous S4 or the M3. I don't feel that manuals are more connected to a car, and I am happy to go around you with a DCT on any course. Long live the dual clutch, check out Porsche or Nissan GTR if you beg to differ!
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08-10-2013, 06:13 PM | #16 |
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Agree with the DCT sentiment here. The auto is great, but it's still quite easy to feel the "slush" when you gun it in manual mode. It's not necessarily the "speed of shift" but it's the grab and impulse of acceleration that really sets them apart - blipping the throttle to rev match.
Did the BMW UDE thing and drove a 640, 328ix and A7 all with the same ZF8. They all felt markedly sluggish compared to my s-tronic, which as I learned here, is not even up to par with what Audi has on the R8 or RS5. GIAC is offering a tune for the B8 S4 dsg which supposedly makes shifts much quicker and removes some of hunting. I've never driven the M-DCT, so can't comment on the comparison. A DCT is not without fault though, it can sometimes shift awkwardly at low speed, mostly cause it has to guess what your left foot would be doing. |
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08-10-2013, 06:21 PM | #17 |
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08-11-2013, 11:21 AM | #18 |
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Can someone please educate me on what a ZF is?
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08-11-2013, 11:48 AM | #19 |
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08-11-2013, 12:20 PM | #20 |
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The ZF8 is the new (also best) slushbox in BMWs. It's an 8-spd automatic, known for its seamless shifting. It can be equipped with paddles on BMW, which come with the Sport Automatic option (higher shift points). It's the transmission used in iirc the B8.5 Audi A4, C7 Audi A6/7, A8, Q5, Q7, RS6/7, and non-PDK Porsche Cayennes/Panameras.
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08-11-2013, 12:38 PM | #21 |
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Porsche uses Aisin ( Japanese, partly Toyota owned ) 8-speed ATs not ZF. Cayennes are Aisin only ( or MT ), the PDK is not suitable for towing and off-roading. The PDK in the Panamera however is from ZF ( The AT in the Panny hybrid is from Aisin )
BMW's DCT is from Getrag ( German ). ZF makes more than transmissions, they for example also make the ARS systems that BMW uses in some models. Last edited by solstice; 08-11-2013 at 12:52 PM.. |
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08-11-2013, 08:01 PM | #22 |
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The ZF boxes are also somewhat modular, in that they can be mated with different type of torque converters and in different packages. ZF is working with Chrysler on a ZF9 which is supposed to be on the new grand Cherokee and I think the Ram. ZF is a German automotive supplier that makes all kinds of things, similar to TRW, Continental, Bosch, Borg Warner etc.
One thing that hasn't been pointed out is that DCT's tend to have lower torque/HP ratings. Audi (who are pretty anti manual) use the ZF slushboxes on their top of the line models like S7, S8, RS6, RS7 (I could be wrong on some of those). Edit - just realized the M5 uses a DCT, so torque limits of Audi S-tronic is probably more that their DCT's aren't as capable as the M-DCT. Last edited by drob23; 08-11-2013 at 08:07 PM.. |
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