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Merits of BMW SMG3 vs Audi DSC

MEnthusiast said:
This is true. However, if the mindset at BMW is SMG is the way forward, then their logic would be that the rest of the world is not losing out (whereas in the past (E36 M3) we felt like we were not getting the most advanced technology), BMW is just making an accommodation to their American customers who insist on the old way. No matter what though, I say thank you to BMW. :flag:
Yes, I agree with the extension of gratitude to BMW AG and especially BMWNA for putting pressure on the mother ship to meet customer demand.
While I also agree that this is probably just a stay of execution for the traditional manual gearbox, I suspect that future transmissions will more resemble Audi's DSG gearbox than BMW's SMG. Far smoother, almost instantaneous gear changes, no loss of engine power, less complex software/electronics. The only issue might be wear issues for TWO clutches instead of one! JMHO. :cheers:
 

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Re: My visit at the M-Gmbh

I would be interested in seeing a technical discussion of the relative technical merits of SMG and DSG. I would think that the two clutches of DSG would radically reduce the momentum differences in the two sides of the gearbox to not only speed shifts, but to simultaneously reduce the wear on the transmission (e.g., to the synchros) and maybe even reduce some of its requisite bulk. However, nothing is free and I would enjoy hearing about the trade-offs.

Tom
 

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Re: My visit at the M-Gmbh

Michael, Tom,
I think there have been some discussions on the boards. I am purely going from memory, but I think one issue -for now at least- with DSG is its ability to handle big power. It also is very fast and smooth for upshifts, but supposedly a little slower than SMGII for downshifts.

It is certainly fun to learn all about the new possibilities that are coming out.

As an aside, although it was viewed as inferior by comparison to the Euro model, I loved my E36 USA M3. I have to give kudos to BMWNA for knowing what its customers wanted in terms of technology and pricing. They hit a home run with that car and I wonder how the future of M in the US would turn out differently (or not) if that car did not do well.

Dan,
Its my experience that info takes time to filter on down through the channels so the people who you would think should know are often the people last to know. The internet has only made this more difficult for them.
 

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Re: Merits of BMW SMG3 vs Audi DSC

DSG is in may ways better than SMG3.

Advantages of DSG:
* Faster shifts, time can effectivly be zero.
* Shifts can be smoother as there is no interuption in power deliverly.

Disadvantages of DSG:
* Possibly more weight, two clutches and more actuators are needed.
* Possibly more rotating mass, again depends on the relative mass of the clutches.
* Preselection glitches. If the user skip shifts or does somethign other than the shift the transmision is predicting the system will hesitate while it re-preselects the correct gears.

Advantages of SMG:
* Lower development cost, more similar to a normal manual.
* Single clutch, more robust and possibly lighter.
* Predictible gear selection time.

Disadvantages of SMG:
* Power interuption on gear change.
* Slowest shifting times


Advantages of CVT:
* Ideal gear ratio 100% of the time
* Zero effective shift times (assumes small changes in ratio)

Disadvantages of CVT:
* Driver reliant on computer for gear ratio choice.
* Systems with manual map are slower than just using D
* Limited torque handling.


In the end I expect CVT will win the majority of "normal" cars. The limited torque limits really only apply to high power cars. For those DSG is the next best option as it will do the right thing when being driving hard. Most of its stumbles are in around town situations. However, even there its likely to be smoother than an SMG if more slugish at times.
 

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Re: My visit at the M-Gmbh

MEnthusiast said:
As an aside, although it was viewed as inferior by comparison to the Euro model, I loved my E36 USA M3. I have to give kudos to BMWNA for knowing what its customers wanted in terms of technology and pricing. They hit a home run with that car and I wonder how the future of M in the US would turn out differently (or not) if that car did not do well.
I also loved my E36 M3. However, I don't think I would have been harmed or the car fared any worse in the US market had we received the Euro engine with its extra ~90hp (from aging memory).

Enigma, thanks for your analysis.

Tom
 

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Roundel did a recent comparison of SMG (I believe it was SMG II, not III) and the Audi DSG.

The general consensus was the SMG was a better SMG and the DSG was a better automatic.
 

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Re: Merits of BMW SMG3 vs Audi DSC

Enigma said:
* Preselection glitches. If the user skip shifts or does somethign other than the shift the transmision is predicting the system will hesitate while it re-preselects the correct gears.
Good point... this could be a real pain in the ***. In fact, shift times could be even higher than SMG.

As for the Roundel article, I think the M3 was a major reason for the transmission "ratings" in the article.
 

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As an aside

Enigma,
Thanks for the break down. Many DSG reviews say the system will upshift automatically, even when in "sport" mode. I would think this is purely a software issue and could be reprogrammed so the transmission would hold a gear, do you know if there is a reason why they do this besides the decision that they did not want customers to bump into the red line?

Tom,
I remember reading that if BMW NA brought the car in without the different engine and drivetrain, the E36 would have cost ~$10,000 more. I think that would have had an impact. This was the biggest selling M car ever in the USA. If you go back to before the US E36 M3 and look at the car market and then look at what happened after you see the emergence of AMG and Audi S as bigger market successes as well. My personal opinion is the E36 US M3 busted this segment open by showing there is a viable market out there.

As far as I am aware they brought the cost down by using a tuned version of the "M" designation engine from the regular E36; while the Euro spec E36 M3 used a "S" designation engine, like the rest of the M cars use. For more see:

http://www.bmwworld.com/models/m3_e36.htm


I also think the E36 USA M3 kept the same drive train as the standard E36, keeping the open diff instead of the Euro Specs LSD. I know a guy who used to race his E36 USA M3 and bemoned the open diff.

To bring this back to the discussion, I really wonder if things had gone differently, where would this discussion be today? We're talking about incredible engineering in these new gearboxes and the market has got to exist for them. I think no USA E36 M3 success= very different M market today. JMHO :byee55amg

Speaking of Roundel, here is some things I found:

http://www.bmwcca.org/Roundel/rdelfset.shtml

Road & Track
http://www.roadandtrack.com/article.asp?section_id=20&article_id=1324&page_number=1

http://www.roadandtrack.com/article.asp?section_id=6&article_id=546&page_number=1

Edmunds:
http://www.edmunds.com/insideline/do/Drives/Followup/articleId=102723

Canadian Driver:
http://www.canadiandriver.com/articles/jk/031119.htm

AudiWorld:
http://www.audiworld.com/features/tests/2004tt32.shtml
 

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Re: Merits of BMW SMG3 vs Audi DSC

Enigma said:
Advantages of CVT:
* Ideal gear ratio 100% of the time
* Zero effective shift times (assumes small changes in ratio)

Disadvantages of CVT:
* Driver reliant on computer for gear ratio choice.
* Systems with manual map are slower than just using D
* Limited torque handling.


In the end I expect CVT will win the majority of "normal" cars. The limited torque limits really only apply to high power cars. For those DSG is the next best option as it will do the right thing when being driving hard. Most of its stumbles are in around town situations. However, even there its likely to be smoother than an SMG if more slugish at times.
Funny thing is that the FIA didn't know how fast to declare a rule that did forbid the use of CVT in races. Just seconds after a very succesfull test by, correct me if I'm wrong, the Williams team, years ago.

Personally I think they where affraid of the impact that the use of this kind of transmission could have on the sport (and mayby on road cars), but it shows the potential for this kind of gearing. Permission to use CVT in race conditions would provide a big boost in the development of a transmission that gives an engine to perform mostly in his optimal rev range. What a dream, always optimal performance, always the optimal mix between fuel consumption and power delivery. But maybe I'm to much a dreamer.
 

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Re: Merits of BMW SMG3 vs Audi DSC

Guust Flater said:
Permission to use CVT in race conditions would provide a big boost in the development of a transmission that gives an engine to perform mostly in his optimal rev range. What a dream, always optimal performance, always the optimal mix between fuel consumption and power delivery. But maybe I'm to much a dreamer.
Yeh - but the sounds coming from an engine at full power linked to a CVT gearbox sounds very much like a diesel generator - chugging away at a constant rpm, instead of the beautiful singing through the revs of an engine linked to a conventional gearbox.
 

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Re: Merits of BMW SMG3 vs Audi DSC

kees said:
Yeh - but the sounds coming from an engine at full power linked to a CVT gearbox sounds very much like a diesel generator - chugging away at a constant rpm, instead of the beautiful singing through the revs of an engine linked to a conventional gearbox.
So you don't want optimal performance of both car and engine? If it's for the sound maybe an engine-sound DVD would be an item for the option list.

Withouth kidding, why wasn't this transmission approved by an institute like the FIA? Pressure that came out of the traditional industry? IMHO it has so much potention, as mentioned before by Enigma in this thread.

Guust
 

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Re: Merits of BMW SMG3 vs Audi DSC

Guust Flater said:
So you don't want optimal performance of both car and engine? If it's for the sound maybe an engine-sound DVD would be an item for the option list.
So next we will have dubbing of racecars? ;)

Withouth kidding, why wasn't this transmission approved by an institute like the FIA? Pressure that came out of the traditional industry? IMHO it has so much potention, as mentioned before by Enigma in this thread.
No idea - I would imagine the conventional industry (Getrag, ZF, etc) didn't like the idea of a new concept.
 

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Hello!

CVT was prohibited by the FIA because it would bring greater speeds and costs. Well, FIA is (generally) against both of those, so no second guessing here...
And technically, it's very easy to prohibit a CVT (just state that there must be fixed gear ratios... like stating that engines must have pistons effectively rules out rotary technology without mentioning it...).

Williams tested this in Monza. Maybe someone can ask Patrick Head for the results... some of them are posted on the net.

About application for production cars:

1. F1 engines have max 400Nm (I'm being generous, but it's not much less than that). CVTs can currently handle arround 300Nm, no F1 wouldn't bring anything really new. Now, if they had it in the turbo days, it might :p ;).

2. People find it very strange to drive a CVT car with a "correct" CVT programing. This is because there are only two points where the engine is desirable to use. Max efficiency (usually very near peak torque rpms and 90% throttle) or max power. The fact that engine speed doesn't change is very confusing for drivers and whenever makes went for this approach the costumer didn't like it. Instead you get a CVT but programmed to act close to an auto trans and sometimes you get manual control of it, and can sequentially select pre-memorized gears. Unfortunatelly CVT eficiency is very low. For all it's possible advantages (for running always at the optimum point) a recently developed CVT doesn't have any better performance or fuel economy than other types of transmissions. If you go to older CVTs, it's very bad, worse than auto by a long shot.

Hope 2005 brough you good stuff (ok, i now the really good is coming in april for some, jun and sept ;)
 

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Re: As an aside

Nope, the NA E36 M3 had the euro M3 spec drivetrain with with an LSD differential and lower ratio rear end than the standard 3 series.

MEnthusiast said:
I also think the E36 USA M3 kept the same drive train as the standard E36, keeping the open diff instead of the Euro Specs LSD. I know a guy who used to race his E36 USA M3 and bemoned the open diff.
 

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MEnthusiast said:
I remember reading that if BMW NA brought the car in without the different engine and drivetrain, the E36 would have cost ~$10,000 more.
That seems much higher a difference than reasonable. If I recall, the E46 M3 with its Euro/world-spec engine was only a few thousand more than the E36. I bet there was a price increase for the E46 in Europe as well. I would be surprised if the marginal cost difference to BMW were more than a grand or two.

Even if the difference were $5,000, would you or anyone on this board not gladly fork this over for the enormous difference in power? With that said, you are completely correct that the E36 M3 was tremendously successful and contributed mightily to the prominence of M.

Tom
 

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An euro e36 M3 in the US might not have been as sucessful. Remeber the E30 M3 was a "euro" car and it didn't do particulary well in the US. you have to remember enthusiasts only account for a very small percentage of the general car buying population. There is just not enough of us for BMW to make money on. So, a softer and cheaper M3 migh very well have been the key to the E36 M3 sucess in the US. Even now if you tell most people that a new M3 cost close to $60k they would just tell you that it's way too much money to pay for a 3 series BMW.
 

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Tom,
The E46 M3 was designed,the USA was then ~50% of the M market. I have a feeling the E36 M3 was designed much more for a European audience. As for the price- NA obviously thought it mattered since they designed a US spec M3. It was a different car world back then, the HP wars had not really heated up that badly yet.

dmz,
Thanks- I will now have something to bust on my friend with! :cheers:
 
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