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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > General E90 Sedan / E91 Wagon / E92 Coupe / E93 Cabrio > ZSG transmission (dual clutch) apparently coming along great



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      05-17-2006, 02:39 PM   #45
inTgr8r
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Quote:
You want to be able to go direct from say, 5th to 2nd gear. My guess is that ZSG should have a big enough brain to prevent money shifts.
The Audi DSG prevents this
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      05-17-2006, 03:05 PM   #46
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I'd like to drive one of the DSG's now. Maybe I'll head over to the Audi dealership later this week...
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      05-17-2006, 05:18 PM   #47
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I drove the VW Golf GTI with the DSG. It's great, but A) I don't like the way it upshifts for you when you readline - it's idiotproofed, and B) I don't wanna buy a frontwheel drive or quattro VW or Audi. I want this on a BMW! Don't you? Gimme it, now
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      05-18-2006, 01:11 PM   #48
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Quote:
Originally Posted by JamieA
I think with all the technology they have these days, they could have offered the DSG with an H pattern... I know I sound like a dinosaur, but I like putting my hand on the stick and knowing subliminally what gear I am in, and the rhythm and flow of gear changing...
This is really not practical or desireable to do. It is also at odds with the purpose of the design as well. I'll try to explain why.

There are 2 lay shafts in the tranny and most of the time 2 gears are engaged at the same time (although only one clutch is engaged and only one gear is driving the car). The actual transition from one gear driving the car to the next takes places at a different time than the engagement of that gear in the gear box (see my earlier post and below).

When you are driving in say, 3rd gear, the computer will decide whether to preselect 4th or 2nd gear on the other lay shaft based on whether it thinks you are accelerating or decelerating. It does this using inputs from already existing sensors in the car ie: throttle position sensor, ABS senors and yaw and pitch sensors from the stability control system.

Let's say you are holding in 3rd gear, accelerating and decelerating in some bends. In this instance the transmission may shift the preselected gear on the other lay shaft back and forth between 2nd and 4th depending on the dynamics of the moment. It has to be ready for whatever may happen.

This must be controlled by a computer that has complete control over the clutch(es) and the shifter forks on the tranny. It is really difficult to have a conventional H-pattern shifter as the selector for this. When you "select" a gear with the shifter there is no actual gear shift occuring in the transimission just a change between the 2 clutches. An H-pattern shifter could not be mechanically connected to the gear box it would have to be actuating a series of electrical swithces.

But, remember that, in addition to being a semi-automatic, the tranny also has to function as an automatic. It will probably have a fully automatic mode where you put it in "D" and go, but it may also have to upshift by itself in semiautomatic mode to protect the engine. What are you going to do in these instances, have the H-pattern shifter flopping around by itself so that it is in the correct position in the pattern for the gear the car is actually in?

This really requires some type of a two position "up-down" shifter control such as paddles or some sort of "slap-stick" shifter.
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      05-18-2006, 01:31 PM   #49
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Quote:
Originally Posted by goldminer
This is really not practical or desireable to do. It is also at odds with the purpose of the design as well. I'll try to explain why.

There are 2 lay shafts in the tranny and most of the time 2 gears are engaged at the same time (although only one clutch is engaged and only one gear is driving the car). The actual transition from one gear driving the car to the next takes places at a different time than the engagement of that gear in the gear box (see my earlier post and below).

When you are driving in say, 3rd gear, the computer will decide whether to preselect 4th or 2nd gear on the other lay shaft based on whether it thinks you are accelerating or decelerating. It does this using inputs from already existing sensors in the car ie: throttle position sensor, ABS senors and yaw and pitch sensors from the stability control system.

Let's say you are holding in 3rd gear, accelerating and decelerating in some bends. In this instance the transmission may shift the preselected gear on the other lay shaft back and forth between 2nd and 4th depending on the dynamics of the moment. It has to be ready for whatever may happen.

This must be controlled by a computer that has complete control over the clutch(es) and the shifter forks on the tranny. It is really difficult to have a conventional H-pattern shifter as the selector for this. When you "select" a gear with the shifter there is no actual gear shift occuring in the transimission just a change between the 2 clutches. An H-pattern shifter could not be mechanically connected to the gear box it would have to be actuating a series of electrical swithces.

But, remember that, in addition to being a semi-automatic, the tranny also has to function as an automatic. It will probably have a fully automatic mode where you put it in "D" and go, but it may also have to upshift by itself in semiautomatic mode to protect the engine. What are you going to do in these instances, have the H-pattern shifter flopping around by itself so that it is in the correct position in the pattern for the gear the car is actually in?

This really requires some type of a two position "up-down" shifter control such as paddles or some sort of "slap-stick" shifter.
I know how it works, so am aware of the problems my suggestion woudl cause. I was just talking generally really about how a good ol' manual can be more satisfying. IMO a DSG is the lesser of any auto-evils.

As for some of your design issues:

1. Yes the linkage would have to be electronic, no biggie, as it already is in a DSG isn't it?

2. Have a "Gear" called "D" if you want auto

3. Otherwise, the computer SHOULD NOT SHIFT, but hold the gear. The revlimiter provides ample engine protection, and I don't need a nanny to protect me from a money shift. Sometimes life is better with the safety catch off...

4. The computer would have enough time to pre-select a gear as you move the stick. SMGs already shift in very short periods of time, their roughness is only because they are actuating a single clutch, the DSG with it's two sets of gears and clutches should be able to shift quick and still be smooth.

The bigest real issue in an H pattern, and the reason they probably haven't done it is really the fact that the DSG is designed to go from odd-to-even or even-to-odd gear selections. An H pattern would allow a user to skip a gear (as I do quite frequently with my 6sp) and go from even-to-even or odd-to-odd. This quite simply is impossible with a DSG unless the computer does this by temporarily engaging the interstitial gear, which would not be a very refined experience!!
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      05-18-2006, 02:15 PM   #50
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Quote:
Originally Posted by JamieA
4. The computer would have enough time to pre-select a gear as you move the stick. SMGs already shift in very short periods of time, their roughness is only because they are actuating a single clutch, the DSG with it's two sets of gears and clutches should be able to shift quick and still be smooth.
I disagree with this. The whole and only point to going to dual clutches is to get the shifting of gears in the gearbox away from the time at which the user selects a gear. Otherwise all you have is another tranny similar enough to the BMW SMG or Ferrari F1 style but with an addtional layer of complexity. As you note these SMGs are notorious for not being smooth shifters however, it is my understanding that the SMG roughness is not because of the single clutch. It is because of the shift and clutch work all having to occur at the same time in a very brief interval. This is tricky to get right.

Last edited by goldminer; 05-18-2006 at 02:38 PM.
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      05-18-2006, 02:18 PM   #51
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The Motorcycle type trans would let you do what you want here.
For the double upshift or downshift, you just tap the lever twice when you have the clutch in.
Bikes have had sequential shifters for as long as I recall, and they are a blast to row through the gears. The H while fun, is kind of old school compared to what a manual sequential gear box would be.
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      05-18-2006, 02:40 PM   #52
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Quote:
Originally Posted by fredtoo
...
For the double upshift or downshift, you just tap the lever twice when you have the clutch in.
A question for anyone who has driven the Audi/VW DSG. Can you do a double tap on the shift paddles and go up 2 gears? If so was it smooth?
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      05-18-2006, 02:50 PM   #53
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Quote:
Originally Posted by fredtoo
The Motorcycle type trans would let you do what you want here.
For the double upshift or downshift, you just tap the lever twice when you have the clutch in.
Bikes have had sequential shifters for as long as I recall, and they are a blast to row through the gears. The H while fun, is kind of old school compared to what a manual sequential gear box would be.
My problem is the motorcycle controls are so ingrained, I'd wind up putting my toe under the clutch pedal and trying to lift it while accelerating...
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      05-18-2006, 03:47 PM   #54
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Quote:
Originally Posted by goldminer
A question for anyone who has driven the Audi/VW DSG. Can you do a double tap on the shift paddles and go up 2 gears? If so was it smooth?
Yes, but it sometimes got confused, and the shift time is much longer since it is not ready with the gear you select

The BMW system is supposed to be much improved on up and down shifts of more than 1 gear compared to the older systems out there
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      05-18-2006, 03:55 PM   #55
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Great. Like many of you other manual hard-cores, this may finally be the pseudo-auto that brings me in from the cold.
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      05-18-2006, 04:20 PM   #56
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Resistance is futile!
ZSG, or, DSG or whatever u call it, IS the future. No question about it.
I am sure they will likely offer the good ol' H stick on most of the models eventually. But u might need to wait, like in the case of M5.

I love my stick e36 M3, but if I am to upgrade to e90 M3, it has to be a ZSG box.
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      05-18-2006, 05:18 PM   #57
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JamieA, good use of "interstitial", nice "in-"word

The curse of all auto trannys is the dreaded "D" - it is there, lurking, calling out to you to just leave it in and drive, and, eventually, you give in and use it once...game over: you have become an automaton (not that there is anything wrong with that).
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      05-18-2006, 06:16 PM   #58
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Quote:
Originally Posted by ahmpower
I drove the VW Golf GTI with the DSG. It's great, but A) I don't like the way it upshifts for you when you readline - it's idiotproofed, and B) I don't wanna buy a frontwheel drive or quattro VW or Audi. I want this on a BMW! Don't you? Gimme it, now
If the GLI was RWD (and had a "Package 3" option list) I'd be in one now... and with probably 90% certainty it would have DSG.

I've only done 'around-town' test drives with one, need a bit more seat time to 'feel' it elsewhere. Still something nice about the H pattern on a traditional manual giving very tactile input as to what gear you're in and near-instant access to any other gear... that 'direct shift' mentioned /\ /\ ...
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      05-18-2006, 06:28 PM   #59
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Maybe someone can confirm or deny this - I've heard that as far as vehicle testing and certification goes, each transmission type (auto or manual) counts as a totally different type of car.

That is, an E90 manual counts as one car that needs to be tested and certified, as well as an E90 Step.

If (*if*) this is the case, there could be some substantial savings in having only one transmission type for a model. Perhaps BMW is looking to have a transmission that would suit the folks that like manuals as well as the people that won't buy anything other than automatics....
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      05-18-2006, 08:43 PM   #60
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Quote:
Originally Posted by goldminer
I disagree with this. The whole and only point to going to dual clutches is to get the shifting of gears in the gearbox away from the time at which the user selects a gear. Otherwise all you have is another tranny similar enough to the BMW SMG or Ferrari F1 style but with an addtional layer of complexity. As you note these SMGs are notorious for not being smooth shifters however, it is my understanding that the SMG roughness is not because of the single clutch. It is because of the shift and clutch work all having to occur at the same time in a very brief interval. This is tricky to get right.
You are right, this would be complex to get right.

When I drive one finally, I guess I will get with the program and convert

That should be next week when I get to take the Internal Audit Manager's GTI DSG for a flog

(He does read this forum btw)
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      05-19-2006, 05:06 AM   #61
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Another thing about the Golf GTI DSG: I couldn't get it to do a screetching start from standstill, as it seems to hesitate a bit, and then start slowly, so it feels slower than a manual, until you get going.
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      05-19-2006, 08:01 AM   #62
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That is one of the endearing aspects of the SMG -- that sucker has bite, no sense of hesitation or any slip. Bang, bang, bang. I hope the DSG is not too cushy.
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      05-19-2006, 09:34 AM   #63
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Having driven manuals & auto's all my life, I bought an A3 DSG 15 months ago.

Yes it's smooth and fuel efficient and fast changing and interesting for 5 minutes.

Then you get bored of it. So I sold it at great cost and bought the 330i manual i now love.

There is no benefit on the road with these boxes, it's not a race track where split second changes make fraction of a second differences.

The only benefit is see is to traditional auto owners who can save fuel as the DSG was more economical than the manual. (no torque converter)

BTW the clutches are wet multiplate units which will outlive a dry unit easily.
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      05-19-2006, 09:43 AM   #64
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Quote:
Originally Posted by stressdoc
That is one of the endearing aspects of the SMG -- that sucker has bite, no sense of hesitation or any slip. Bang, bang, bang. I hope the DSG is not too cushy.
Thats the point - with single-clutch-automated-manual-boxes (SMG, ferrari, lambo, F1 etc) the power to the wheels HAS TO BE cut between shifts (briefly) which gives the same feeling as a regular manual, ony with faster shifts.

The DSG type changes smoothly, at full power, from one gear to the next WITHOUT cutting engine power to the wheels, that's the whole idea.

But this gives a rather auto-like feeling of smoothness. Thus I read previously that BM said their dual clutch will be a replacement for the regular autos, not the SMG for sport derivatives as the DSG type lacks the agressive drive and feel they want for M cars etc.
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      05-24-2006, 02:34 AM   #65
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What are the chances of seeing this transmission on the e92 335 early next year... I hate the thought of having to drive an auto. I can't wait!
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      06-13-2006, 07:39 AM   #66
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interesting news on the carconnection.com: per vw product cheif Wolfgang Bernhard the dsg gearbox will replace automatics in all transverse applications! wonder if bmw might follow suit and replace steptronic with their forthcoming dct units( as opposed to replacing the manual which is the prevalent notion)? i had in fact posted a while back that i perceived the dct as more of a competitor to auto than stick.
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