F30POST
F30POST
2012-2015 BMW 3-Series and 4-Series Forum
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > 2012-2019 BMW 3 and 4-Series Forums > General F30 Sedan / F32 Coupe / F36 Gran Coupe Forum > DCT tranny
Steve Thomas BMW
Post Reply
 
Thread Tools Search this Thread
      11-24-2012, 03:45 PM   #23
SamS
Brigadier General
 
SamS's Avatar
 
Drives: 2013 ActiveHybrid 3
Join Date: Jul 2010
Location: Dallas, TX

Posts: 4,513
iTrader: (0)

Quote:
Originally Posted by RPM90 View Post
A dual clutch can skip gears on downshift, but it can't skip like the ZF does, directly to the gear requested, depending on the gear it's in and the gear called for.
The MDCT is smarter/better than just "going directly to the gear requested". The car/computer is smarter than a person. There should be no circumstance where you'd need to go directly from 8th to 2nd. When you hold the downshift paddle on the MDCT, it can instantly drop to the lowest possible gear safe enough for the current engine speed. In other words, it's going to give you the maximum power for the gearing and engine speed combination. There is no point trying to out thinking the ECU (guess that you need to be in 2nd, when 4th might be better), it knows better than us.

The ZF 8AT is a great transmission, but trust me that the Getrag 7sp DCT is better
__________________
SamS is offline  
0
Reply With Quote
      11-24-2012, 07:18 PM   #24
Naambezet
Second Lieutenant
 
Drives: BMW X1 sDrive 20i
Join Date: Apr 2012
Location: Netherlands

Posts: 281
iTrader: (0)

Quote:
Originally Posted by Elk View Post
Yes, we know what the marketing literature states. But is there anything that demonstrates the ZF can/will do a direct eight to two shift as installed in an F30?
I'll try the next time when I'm driving.
Putting it in M8 and then floor it.
Naambezet is offline   Netherlands
0
Reply With Quote
      11-30-2012, 07:38 PM   #25
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by NISFAN View Post
RPM90

You make a big deal about being able to skip gears on a downshift, and I don't refute your information on what gearboxes can and can't.

The question I have is why? Why would you need to downshift 3-4 gears in an instant unless you had fallen asleep at the wheel?

I have driven large braked, sticky tyred M3's on track (DCT versions), stamping on the brakes at the end of the straight going from 6th to a 2nd gear corner, and have never thought 'Jeez this gearbox needs to change down quicker'
It's a great question.

I think that ZF used that information as a way to plug and differentiate how good the AT is.

IN real day to day driving the only advantage I'd say there is is that on multi-gear downshifts it will do 3 gears down and shift only once.
It's practical because of how controlled it is, so there is less chassis motion while coming into a turn, the car settles down quicker before the turn.

Again, I'm only giving information I've gleamed.
I can only speak about how good it is from an AT point of view as I am mainly an MT driver.
For as good as this AT is I still can't put it in the gear I want directly as I can with a MT. With a MT I can go from 6th to 2nd in one motion.
With my AT I have to be really quick on the paddles or lever to hit it 4 times. Going from 8 to 2, I don't think anyone can do it as the trans would start shifting before we could move the paddles/lever 6 times.

How this trans works is worth discussion.
How fast it can skip 6 gears is more about marketing and bragging, imo.
RPM90 is online now  
0
Reply With Quote
      11-30-2012, 07:52 PM   #26
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by SamS View Post
The MDCT is smarter/better than just "going directly to the gear requested". The car/computer is smarter than a person. There should be no circumstance where you'd need to go directly from 8th to 2nd. When you hold the downshift paddle on the MDCT, it can instantly drop to the lowest possible gear safe enough for the current engine speed. In other words, it's going to give you the maximum power for the gearing and engine speed combination. There is no point trying to out thinking the ECU (guess that you need to be in 2nd, when 4th might be better), it knows better than us.

The ZF 8AT is a great transmission, but trust me that the Getrag 7sp DCT is better
Again, the point is that this AT CAN skip that many gears.
The realistic point is that it can do 3 or 4 gear downshifts, for accel or decel, faster than a DCT can, yes, even if you put "M" in front of it.
The 8 to 2 thing is fluff.

The question was not about being "safe" or "trying to out think" the ECU, which I don't know who is trying that, you just brought it up.
Don't know why you're bringing that in.

The point you wanted to discuss/debate is clear, down shift speed and ability to skip gears quicker/slower.
I've given you the info.

I didn't make this up. This information comes from ZF.
You asked, I gave.
But that's just me. I'm a very giving person.

If you like the DCT better, cool. No one's busting your ba11s on that.
The ZF sport AT is one hell of an automatic trans.
Best torque converter trans I've ever driven.
RPM90 is online now  
0
Reply With Quote
      11-30-2012, 07:58 PM   #27
SamS
Brigadier General
 
SamS's Avatar
 
Drives: 2013 ActiveHybrid 3
Join Date: Jul 2010
Location: Dallas, TX

Posts: 4,513
iTrader: (0)

Quote:
Originally Posted by RPM90 View Post
Again, the point is that this AT CAN skip that many gears.
The realistic point is that it can do 3 or 4 gear downshifts, for accel or decel, faster than a DCT can, yes, even if you put "M" in front of it.
The 8 to 2 thing is fluff.

The question was not about being "safe" or "trying to out think" the ECU, which I don't know who is trying that, you just brought it up.
Don't know why you're bringing that in.

The point you wanted to discuss/debate is clear, down shift speed and ability to skip gears quicker/slower.
I've given you the info.

I didn't make this up. This information comes from ZF.
You asked, I gave.
But that's just me. I'm a very giving person.

If you like the DCT better, cool. No one's busting your ba11s on that.
The ZF sport AT is one hell of an automatic trans.
Best torque converter trans I've ever driven.
I made the point because you gave some blatantly incorrect information (DCT not able to skip gears) as fact.

Also, I use the "M" designation, because the DCT in M cars does have different software/design than the non-M DCT cars. I wanted to reference the MDCT, in particular.

All good now?
__________________
SamS is offline  
0
Reply With Quote
      12-01-2012, 10:24 PM   #28
gthal
Colonel
 
gthal's Avatar
 
Drives: 2015 M4
Join Date: Jul 2007
Location: Canada

Posts: 2,901
iTrader: (2)

Garage List
2011 M3  [3.37]
Not debating the ability or benefit of the 8AT being able to downshift directly into a lower gear in auto mode but can it do it in manual mode? That is, if you are in 6th and want to go to 3rd, can you click the shift paddle 3 times and go to third? In the DCT you can. Even if the DCT has to engage intermediate gears it isn't noticeable. When I had my M3, the DCT would up/down shift immediately and could downshift multiple gears in manual mode instantly. The MCT in my C63 is fast but in manual mode can't "skip" gears and it is annoying when driving on a track or aggressively (and I would bet it is every bit as fast or faster than the 8AT in the BMW). The C63 auto claims to shift as fast as 100ms and it is very fast and responsive but it is no where near as responsive as the DCT in the M3 even if the shift speeds are similar... the 8AT is the same... a VERY fast auto but is not as immediate and responsive and direct as a DCT when in manual mode. DCT's cannot be matched in manual mode IMO as they are truly manual transmissions that shift at incredible speed.

My point is that for track/aggressive driving, the DCT is a better and more direct transmission and that is the only time multiple downshifts are needed (most modern transmissions have incredibly quick ""kick down" modes including the DCT). In that case, the only transmission that can do it in manual mode is the DCT... and it does it instantly. I do believe the 8AT is the better transmission for daily driving and is very fast and responsive. The DCT is the transmission of choice for track/aggressive driving IMO. I said this in another thread... there is a reason BMW has a DCT in the M3.
__________________
2015 Austin Yellow M4 | Black Full Merino Leather | DCT
2014 Corvette Stingray | Z51 | Torch Red | 7MT - Sold
2012 C63 Coupe | Performance package | Obsidian Black - Sold
2011 E92 M3 | Jerez Black | Fox Red | DCT | Competition Package - Sold
gthal is offline   Canada
0
Reply With Quote
      12-02-2012, 06:07 PM   #29
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by Elk View Post
Yes, we know what the marketing literature states. But is there anything that demonstrates the ZF can/will do a direct eight to two shift as installed in an F30?
I tried it a few times to see what it can do, and why one would need a 6 gear change.
It works on accel.

If you're in "comfort" auto mode, the trans will shift to 8th by around 40-45mph. Staying at that speed while crusing it's in 8th.
Then, stomp the throttle pedal past into the kick down resistance point, and the trans will down shift to 2nd, and it feels like one shift.
However, that one shift does seem to take just a smidge longer than any single down shift.

I think this capability is for fastest accel if one really needs it.
Still it does do what ZF claims it will do.
Very cool, and very fast.
RPM90 is online now  
0
Reply With Quote
      12-02-2012, 06:12 PM   #30
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by SamS View Post
I made the point because you gave some blatantly incorrect information (DCT not able to skip gears) as fact.

Also, I use the "M" designation, because the DCT in M cars does have different software/design than the non-M DCT cars. I wanted to reference the MDCT, in particular.

All good now?
Sam, I gave some incorrect information, as I should have stated it differently.
And, I have corrected the incorrect/misleading information, and wrote that I was incorrect.
Harping on it again, after I've already admitted and corrected it is arguing for arguments sake.
It's been cleared up.

Again, the point being, the ZF 8spd can downshift by skipping more gears than a dual clutch, DCT, DSG, M DCT.
That's all I was saying.
I wasn't putting the DCT or M-DCT down.

When I'm wrong, I'm very willing to say it and correct it.
I find that to be a good virtue.
I hope that clears it up.

Last edited by RPM90; 12-02-2012 at 06:26 PM.
RPM90 is online now  
0
Reply With Quote
      12-02-2012, 06:22 PM   #31
gthal
Colonel
 
gthal's Avatar
 
Drives: 2015 M4
Join Date: Jul 2007
Location: Canada

Posts: 2,901
iTrader: (2)

Garage List
2011 M3  [3.37]
Quote:
Originally Posted by RPM90 View Post
I tried it a few times to see what it can do, and why one would need a 6 gear change.
It works on accel.

If you're in "comfort" auto mode, the trans will shift to 8th by around 40-45mph. Staying at that speed while crusing it's in 8th.
Then, stomp the throttle pedal past into the kick down resistance point, and the trans will down shift to 2nd, and it feels like one shift.

However, that one shift does seem to take just a smidge longer than any single down shift.

I think this capability is for fastest accel if one really needs it.
Still it does do what ZF claims it will do.
Very cool, and very fast.
Although this is a great feature of the 8AT it is one of the unfortunate downsides of auto transmissions... abrupt downshifts. I always, always, always drive in manual mode because I hate the kick down. Driving along in 7th gear, no power... give the car a bunch of gas and BAM downshift and ROCKET acceleration. It's OK on the highway but around town I don't like it. In manual mode, there are no surprises. This is really just personal preference having driven MT cars for 20 years and now having my second without a clutch pedal. Manual mode gives a little more control than full auto... hence full auto not needed

That's why I like to understand how the "manual" mode in each auto works when buying cars because my transmission is never in auto. From everything I have read, it seems like the 8AT in the BMW is capable in manual mode which is a good thing.
__________________
2015 Austin Yellow M4 | Black Full Merino Leather | DCT
2014 Corvette Stingray | Z51 | Torch Red | 7MT - Sold
2012 C63 Coupe | Performance package | Obsidian Black - Sold
2011 E92 M3 | Jerez Black | Fox Red | DCT | Competition Package - Sold
gthal is offline   Canada
0
Reply With Quote
      12-02-2012, 06:25 PM   #32
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by gthal View Post
Not debating the ability or benefit of the 8AT being able to downshift directly into a lower gear in auto mode but can it do it in manual mode? That is, if you are in 6th and want to go to 3rd, can you click the shift paddle 3 times and go to third? In the DCT you can. Even if the DCT has to engage intermediate gears it isn't noticeable. When I had my M3, the DCT would up/down shift immediately and could downshift multiple gears in manual mode instantly. The MCT in my C63 is fast but in manual mode can't "skip" gears and it is annoying when driving on a track or aggressively (and I would bet it is every bit as fast or faster than the 8AT in the BMW). The C63 auto claims to shift as fast as 100ms and it is very fast and responsive but it is no where near as responsive as the DCT in the M3 even if the shift speeds are similar... the 8AT is the same... a VERY fast auto but is not as immediate and responsive and direct as a DCT when in manual mode. DCT's cannot be matched in manual mode IMO as they are truly manual transmissions that shift at incredible speed.

My point is that for track/aggressive driving, the DCT is a better and more direct transmission and that is the only time multiple downshifts are needed (most modern transmissions have incredibly quick ""kick down" modes including the DCT). In that case, the only transmission that can do it in manual mode is the DCT... and it does it instantly. I do believe the 8AT is the better transmission for daily driving and is very fast and responsive. The DCT is the transmission of choice for track/aggressive driving IMO. I said this in another thread... there is a reason BMW has a DCT in the M3.
Yes, in manual mode the ZF AT can down shift from 6th to 3rd nearly instantly, just as fast as a dual clutch.
And, it can do it by skipping gears too.
A dual clutch can skip gears as well, but since the gears are on 2 shafts, then how fast it can go from an even number gear to a lower even number gear may require a couple of shifts, and/or take less than a split second quicker.
Can the ZF down shift faster than a dual clutch?
Maybe in some cases, but how much difference does it make is a good question.

I like dual clutch trans, and after having my ZF 335i for a while I'll bet I may like it better as there are still some times when I can feel the torque converter doing it's thing in this trans.
Shift speed is amazing for a torque converter AT, and rivals DCT's.

But, there is a difference in feel. A dual clutch feels more like an MT because it is basically an MT that is automated, but the engine is connected to the trans by a solid clutch/clutches.
The ZF AT, as you know, uses a torque converter so you still feel that especially when driving hard.
In day to day driving though, the ZF AT feels smoother because of the torque converter and how it can dampen the power transfer from engine to trans.
If BMW had offered a DCT and ZF sport AT, I would likely have gone with the DCT for the reasons I mentioned.

BTW, have you driven an F30 with the sport AT?
If not give it a try. It's VERY impressive for a torque converter trans.
RPM90 is online now  
0
Reply With Quote
      12-02-2012, 06:27 PM   #33
MaestroAl
Major
 
Drives: Superman 330D M Sport
Join Date: Aug 2012
Location: UK

Posts: 1,194
iTrader: (0)

At least the ZF8AT is an auto that can be driven in manual without it being "weird" like a normal auto driven in manual And I know exactly what you mean. Sometimes I just want some power but I don't want to change gear. it'll always be an idiosyncrasy of an auto box that we have to put up with but at least for the other 99% of the time it's great
__________________
"Superman 330D M Sport" Estoril Blue / Coral Red
2PF|ZAP|ZMP|ZVI|2VF|3AP|420|488|494|5DC|688|6NR
IT ARRIVED!
MaestroAl is offline   United Kingdom
0
Reply With Quote
      12-02-2012, 06:36 PM   #34
gthal
Colonel
 
gthal's Avatar
 
Drives: 2015 M4
Join Date: Jul 2007
Location: Canada

Posts: 2,901
iTrader: (2)

Garage List
2011 M3  [3.37]
Quote:
Originally Posted by RPM90 View Post
Yes, in manual mode the ZF AT can down shift from 6th to 3rd nearly instantly, just as fast as a dual clutch.
And, it can do it by skipping gears too.
A dual clutch can skip gears as well, but since the gears are on 2 shafts, then how fast it can go from an even number gear to a lower even number gear may require a couple of shifts, and/or take less than a split second quicker.
Can the ZF down shift faster than a dual clutch?
Maybe in some cases, but how much difference does it make is a good question.

I like dual clutch trans, and after having my ZF 335i for a while I'll bet I may like it better as there are still some times when I can feel the torque converter doing it's thing in this trans.
Shift speed is amazing for a torque converter AT, and rivals DCT's.

But, there is a difference in feel. A dual clutch feels more like an MT because it is basically an MT that is automated, but the engine is connected to the trans by a solid clutch/clutches.
The ZF AT, as you know, uses a torque converter so you still feel that especially when driving hard.
In day to day driving though, the ZF AT feels smoother because of the torque converter and how it can dampen the power transfer from engine to trans.
If BMW had offered a DCT and ZF sport AT, I would likely have gone with the DCT for the reasons I mentioned.

BTW, have you driven an F30 with the sport AT?
If not give it a try. It's VERY impressive for a torque converter trans.
Great summary!

Only been in the new 3 series once so limited experience. My C63 has the MCT auto tranny and I bet it is very, very similar in feel and performance to the ZF. The shifts are similar in speed to the DCT but it is an auto (wet clutch instead of a torque converter). It is also a great transmission and FAST. From everything I have read, the ZF 8AT is great and would be a great choice if someone decided not to go 6MT. The hard decision will be 6MT or 8AT... the fact that the 8AT is so capable makes the decision that much more difficult.
__________________
2015 Austin Yellow M4 | Black Full Merino Leather | DCT
2014 Corvette Stingray | Z51 | Torch Red | 7MT - Sold
2012 C63 Coupe | Performance package | Obsidian Black - Sold
2011 E92 M3 | Jerez Black | Fox Red | DCT | Competition Package - Sold

Last edited by gthal; 12-02-2012 at 06:43 PM.
gthal is offline   Canada
0
Reply With Quote
      12-02-2012, 07:15 PM   #35
bimmerjph
Lieutenant Colonel
 
bimmerjph's Avatar
 
Drives: 2002 BMW 325i
Join Date: Oct 2011
Location: Tennessee

Posts: 1,955
iTrader: (0)

Quote:
Originally Posted by 949 View Post
if they put a double clutch transmission in im going to buy this car.
The ZF HP8 sport auto is damn near as fast as a DCT, but it is lighter, less complicated, and is better around town. The only reason to want a DCT is for "my car is better than your because it has two clutches" arguments.

Having only a manual and fast auto option is best because a DCT is not going to be good for people that just want a luxury car (which is the majority of people that get autos), and people that want manuals are going to get manuals. My advice to you is teach your family to drive a stick.
bimmerjph is offline   United_States
0
Reply With Quote
      12-02-2012, 09:16 PM   #36
RPM90
Major General
 
Drives: 335i Msport w/sport AT
Join Date: Mar 2006
Location: Chicago

Posts: 6,084
iTrader: (1)

Quote:
Originally Posted by gthal View Post
Great summary!

Only been in the new 3 series once so limited experience. My C63 has the MCT auto tranny and I bet it is very, very similar in feel and performance to the ZF. The shifts are similar in speed to the DCT but it is an auto (wet clutch instead of a torque converter). It is also a great transmission and FAST. From everything I have read, the ZF 8AT is great and would be a great choice if someone decided not to go 6MT. The hard decision will be 6MT or 8AT... the fact that the 8AT is so capable makes the decision that much more difficult.
MT or AT that's the big question for sure.
I'm an MT driver at heart and I too wrestled with getting an automatic with a torque converter.
So, I tried and tested as much as I could to make a decision.
When I first tried it I was amazed at the sport AT's performance.
I had never felt another AT like this. Did a bunch of reading and was very impressed with the thought ZF put into this trans to make it feel like a cross between a dual clutch and an TC auto.
So, I decided to try it. Since I lease I figured that I I didn't like it, then I'll just go back to a MT.

There really is not comparison between a MT and AT. They feel different and they function in different ways, and the drivers involvement is different too. The better comparison is between a dual clutch, this TC AT, and other TQ AT's, that's where the real comparison lies.
The ZF AT doesn't give you the same feel of involvement as a MT does, and if one is hoping that a manually operated AT is the same as an MT, then it's really not the trans for them.
But if one wants to try an AT that is truly amazing in how it performs in full auto mode and then in manual mode, they will be impressed, and all other TC AT's pale in comparison.

Sometimes I wish I would have chosen the MT, but overall I am really happy with this AT, well at least when it's working correctly.
Mine is gonna need to be looked at.
RPM90 is online now  
0
Reply With Quote
      12-03-2012, 01:21 AM   #37
lfcorrea
New Member
 
lfcorrea's Avatar
 
Drives: 2012 X3 35i, 2010 128i
Join Date: Nov 2012
Location: Honolulu

Posts: 11
iTrader: (0)

Quote:
Originally Posted by RPM90 View Post
MT or AT that's the big question for sure.
I'm an MT driver at heart and I too wrestled with getting an automatic with a torque converter.
So, I tried and tested as much as I could to make a decision.
When I first tried it I was amazed at the sport AT's performance.
I had never felt another AT like this. Did a bunch of reading and was very impressed with the thought ZF put into this trans to make it feel like a cross between a dual clutch and an TC auto.
So, I decided to try it. Since I lease I figured that I I didn't like it, then I'll just go back to a MT.

There really is not comparison between a MT and AT. They feel different and they function in different ways, and the drivers involvement is different too. The better comparison is between a dual clutch, this TC AT, and other TQ AT's, that's where the real comparison lies.
The ZF AT doesn't give you the same feel of involvement as a MT does, and if one is hoping that a manually operated AT is the same as an MT, then it's really not the trans for them.
But if one wants to try an AT that is truly amazing in how it performs in full auto mode and then in manual mode, they will be impressed, and all other TC AT's pale in comparison.

Sometimes I wish I would have chosen the MT, but overall I am really happy with this AT, well at least when it's working correctly.
Mine is gonna need to be looked at.
I never thought the decision would be this hard, I've been to 4 test drives and still haven't decided, but my gut feeling is to just stick to a MT...
lfcorrea is offline  
0
Reply With Quote
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 09:31 PM.




f30post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST