# m3 smg..auto?



## a18eem (Sep 24, 2005)

Hi everyone!
I have been thinking of changing my car ,2 choices so far are the late audi rs4 or the bmw m3. I was looking for an auto box if possible and know the m3 comes with an smg gear box.
Can anyone put some tell me what the smg is...is it an auto or manual or a cluchless manual or something else??

Thanks a lot :wink:


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## tehdarkstar (Jul 24, 2006)

SMG is a semi-auto (cluchless) and it comes with paddles on the steering wheel for you to change gears. It is conceptualy similar to Audi's DSG/S-tronic.


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## Carlos (May 6, 2002)

Yep, its a manual gearbox controlled by electro-hydraulics. Similar to DSG but I think DSG is more advanced due to the dual clutch.


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## YELLOW_TT (Feb 25, 2004)

Carlos said:


> Yep, its a manual gearbox controlled by electro-hydraulics. Similar to DSG but I think DSG is more advanced due to the dual clutch.


Yep the DSG is much better than the SMG in the BMW


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## Kieran (Aug 5, 2005)

DSG is not a maual box were the bmw is the dsg is far better i had the tt dsg
and my cousin has a m3 smg and the gear box in my view is crap 
fast driving means saw neck. where as dsg you go faster to see if u can notice a change at all

Audi over BMW anyday


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## W7 PMC (May 6, 2002)

Wrong, wrong wrong

SMG is Sequential MANUAL Gearbox & is a true clutchless Manual gearbox. It does have a rough auto mode but most owners never seem to use this & it's hardly surprising. Changes can be paddle or stick made & their is no park mode & as it's MANUAL you can't hold the car on a hill without the brakes etc. (makes parking quite tricky).

DSG is an AUTO box with a manual overide (paddles etc.) an advanced version of Tiptronic. DSG is far smoother than SMG but as it's an advanced auto, it should be. It's perhaps correct that DSG is a little more advanced than SMG in certain areas but they are chalk & cheese when looking at gearbox mechanics & requirements.

DSG is better for cruising & ppushing on, but in my experience it aint better for involved driving & traffic light grand prixs etc.

I've only driven a DSG for about 200miles & of course an SMG for 5000+ miles. Also be aware that SMG is now on it's 3rd generation. The original SMGI in the 1st SMG M3's was very rough, this was improved in later M3's & the CSL with SMGII. The M5 has SMGIII which is 20% quicker & smoother than SMGII. In the new V8 M3 later this year/next year, it's expected BMW will launch SMGIV & that will be about 20% quicker & smoother again.

Sum up:

SMG is MANUAL with auto mode.
DSG is AUTO with manual mode.


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## Carlos (May 6, 2002)

I'm really not sure about that. A traditional automatic gearbox uses a torque converter. DSG does not. AFAIK the DSG is similar to SMG except it uses two clutches so it can select the next gear for seamless changes. Based on this, DSG is far more closely related to SMG, and not closely related to Tiptronic at all.

I really don't think DSG is an auto at all. Of course it has an auto mode, but in terms of its components, I think it is a manual gearbox that is controlled by electronics and hydraulics. Could be wrong!


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## Carlos (May 6, 2002)

This would appear to confirm my view

http://en.wikipedia.org/wiki/Direct-Shift_Gearbox


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## W7 PMC (May 6, 2002)

Carlos said:


> I'm really not sure about that. A traditional automatic gearbox uses a torque converter. DSG does not. AFAIK the DSG is similar to SMG except it uses two clutches so it can select the next gear for seamless changes. Based on this, DSG is far more closely related to SMG, and not closely related to Tiptronic at all.
> 
> I really don't think DSG is an auto at all. Of course it has an auto mode, but in terms of its components, I think it is a manual gearbox that is controlled by electronics and hydraulics. Could be wrong!


Carl,

I'm certainly no DSG expert (not really an SMG expert either), however all i've read states the DSG is akin to an Auto & not a manual. So an auto with manual functionality. That article below just mentions the dual clutches, but all gearboxes have clutches, auto or manual. I thought that the DSG box DOES have a Torque Converter but i'm not 100% sure.

I do know they drive very different & to feel the changes the SMG feels manual (ranging from light changes to very aggresive changes depending on what setting is used), where as the DSG feels far more like the Tiptronic box i had in the RS6 or Steptronic in my Bimmer 535d.


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## Carlos (May 6, 2002)

Hee hee all I've read says that DSG is a manual with auto functionality - ie very similar to DSG but with the extra technology of a twin clutch (which is what allows for seamless changes).

I'm almost 100% sure that DSG does NOT have a torque converter.


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## Carlos (May 6, 2002)

W7 PMC said:


> I'm certainly no DSG expert (not really an SMG expert either)





W7 PMC said:


> Wrong, wrong wrong


Oh I thought since you were so sure about it that you must be an expert :roll: :wink:

Have a look here:

http://www.evo.co.uk/carreviews/evocarreviews/53636/vw_golf_gti_dsg.html



> The rise and rise of the automated dual-clutch manual gearbox is upon us


I've certainly not seen the motoring press refer to DSG as an automatic, always as automated manual or some similar phrase.


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## Kieran (Aug 5, 2005)

The dsg is auto like someone else said its got park reverse and nutural 
if it was a manual it would not creep like an automatic at lights when you take your foot off of the brake 
plus insuring it which have done and v5 state automatic


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## Carlos (May 6, 2002)

Kieran said:


> The dsg is auto like someone else said its got park reverse and nutural
> if it was a manual it would not creep like an automatic at lights when you take your foot off of the brake
> plus insuring it which have done and v5 state automatic


Oh right so despite all the technical articles to the contrary its an auto.

All the cars I've ever owned (auto and manual) have had neutral and a reverse gear. You don't think in this day and age that it would be possible for Audi to develop a "park" interface on a computer-controlled gearbox? :roll:

Nobody is arguing that it doesn't have the functions of an auto, but underneath it is a manual gearbox being controlled automatically.


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## W7 PMC (May 6, 2002)

Carlos said:


> Kieran said:
> 
> 
> > The dsg is auto like someone else said its got park reverse and nutural
> ...


Good points Carl, however the main point is how they perform & i can't give you the technical patter but can give the the characteristics.

SMG has no park so it's parked in Neutral with the hand-brake applied (same as a manual). If you're in any gear & remove your foot off the brake, the car will roll forwards or backwards assuming you're on an incline (no clutch to ride as it's a clutchless manual).

I was not aware the DSG was described as Auto on a V5, but my car is defo stated as manual on my V5.

DSG does have 2 clutches (SMG only has one i guess), but for them to automatically work without a brake on a DSG box, their must be some kind of converter to enable the car to hold a gear without braking if you see what i mean??

I've no real knowledge of intricate gearbox specifications so this is all IMHO having driven both & my understanding of how they both work.


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## garyc (May 7, 2002)

Carlos said:


> Hee hee all I've read says that DSG is a manual with auto functionality - ie very similar to DSG but with the extra technology of a twin clutch (which is what allows for seamless changes).
> 
> I'm almost 100% sure that DSG does NOT have a torque converter.


Carl, I am with you.

DSG/SMG - are eletronically controlled manual gearboxes, clutch (1 or more :wink: ), electronic control and various SW modes.

Automatic. tiptronic, switchtronic: all traditional auto boxes with a torque converter no clutch.

"The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios. The planetary gearset is the device that makes this possible in an automatic transmission. "

Here is full explanation:http://auto.howstuffworks.com/automatic-transmission.htm

"Because a dual-clutch transmission is similar to an automatic, you might think that it requires a torque converter, which is how an automatic transfers engine torque from the engine to the transmission. DCTs, however, don't require torque converters. Instead, DCTs currently on the market use wet multi-plate clutches. A "wet" clutch is one that bathes the clutch components in lubricating fluid to reduce friction and limit the production of heat. Several manufacturers are developing DCTs that use dry clutches, like those usually associated with manual transmissions, but all production vehicles equipped with DCTs today use the wet version. Many motorcycles have single multi-plate clutches. "

Full explanation

http://auto.howstuffworks.com/dual-clutch-transmission.htm

Whether they (SMG, DSG etc) operate as fully automatic, semi-automatic, or electonic manual, is neither here nor there. Having a torque converter is the arbiter. Neither has atorque converter.

BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.


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## Tubbs (Feb 14, 2004)

[/quote]

BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.[/quote]

BMW's M5 SMG (E60) has a twin clutch system already and the SMG in the M3 uses a single clutch system.

The M3 with SMG is great but the auto mode can be a bit jerky. The SMG also has several change speeds to tailor how quick the car changes gear to the way you want to drive.

Its great fun but could get annoying if your a high mileage user doing anything over 15k - 20k per year.


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## a18eem (Sep 24, 2005)

Err..hello guys....so let me get this straight:
The smg can be used as an auto to drive if I feel lazy or her in doors
wants to drive (she only drives auto cars)??? :?:


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## garyc (May 7, 2002)

BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.[/quote]

BMW's M5 SMG (E60) has a twin clutch system already and the SMG in the M3 uses a single clutch system.

*All current BMW SMGs (both e60 and e46) have a single clutch only. *

The M3 with SMG is great but the auto mode can be a bit jerky. The SMG also has several change speeds to tailor how quick the car changes gear to the way you want to drive.

Its great fun but could get annoying if your a high mileage user doing anything over 15k - 20k per year.[/quote]


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## W7 PMC (May 6, 2002)

garyc said:


> Carlos said:
> 
> 
> > Hee hee all I've read says that DSG is a manual with auto functionality - ie very similar to DSG but with the extra technology of a twin clutch (which is what allows for seamless changes).
> ...


Perhaps, but as the characteristics are very different, how can they be the same?? I can't argue the point as i'm not mechanically minded but common sense says they drive & act very differently so they can't really be the same. A Manual is afrer all a manual & they're all the same except the number of gears. An Auto is an Auto whatever it's called (Steptronic, Tiptronic etc. SMG is Sequential Manual Gearbox & i can't recall what DSG stands for.

However having driven both transmissions, the DSG is certainly more akin with an Auto or Tiptronic that i had in the RS6 given it's functionality (perhaps thats just clever software) & the SMG is more akin to a true manual.

If it's just differences in software then Audi have done pretty well, however i know which one feels more involving & more like a true manual gearbox.

I still recall reading an article that stated DSG does operate with a torque convertor but perhaps i mis-read & it was quite some time ago.


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## Carlos (May 6, 2002)

Fair play. I am arguing from the standpoint of what it is, you're arguing from the standpoint of what it feels like.

Since the underlying technology is inarguable (ie what it is) can we agree that DSG is an automated manual gearbox (like SMG), and that its automatic mode is so good (unlike SMG) that to all intents and purposes it feels like an automatic?


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## W7 PMC (May 6, 2002)

Carlos said:


> Fair play. I am arguing from the standpoint of what it is, you're arguing from the standpoint of what it feels like.
> 
> Since the underlying technology is inarguable (ie what it is) can we agree that DSG is an automated manual gearbox (like SMG), and that its automatic mode is so good (unlike SMG) that to all intents and purposes it feels like an automatic?


I can agree with that Carl & i guess it's all credit to Audi that through software development they can make a sequential manual feel more like an automatic, however i'm happier that SMG does not feel like an automatic.

Agreement all round


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## W7 PMC (May 6, 2002)

Carlos said:


> W7 PMC said:
> 
> 
> > I'm certainly no DSG expert (not really an SMG expert either)
> ...


Never spotted this post :lol:

I'm not alone in my understanding of DSG/SMG, as others on this thread thought the same as me, hence why i was convinced i was right, but it turns out i wasn't right. This does happen sometimes, not often but sometimes :wink: :lol:


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## Tubbs (Feb 14, 2004)

garyc said:


> BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.


BMW's M5 SMG (E60) has a twin clutch system already and the SMG in the M3 uses a single clutch system.

*All current BMW SMGs (both e60 and e46) have a single clutch only. *

The M3 with SMG is great but the auto mode can be a bit jerky. The SMG also has several change speeds to tailor how quick the car changes gear to the way you want to drive.

Its great fun but could get annoying if your a high mileage user doing anything over 15k - 20k per year.[/quote][/quote]

E46 is single clutch.

E60 M5 and the M6 are both double clutch unless the guy that trained me at BMW Braknell HQ was wrong?


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## Tubbs (Feb 14, 2004)

garyc said:


> BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.


BMW's M5 SMG (E60) has a twin clutch system already and the SMG in the M3 uses a single clutch system.

*All current BMW SMGs (both e60 and e46) have a single clutch only. *

The M3 with SMG is great but the auto mode can be a bit jerky. The SMG also has several change speeds to tailor how quick the car changes gear to the way you want to drive.

Its great fun but could get annoying if your a high mileage user doing anything over 15k - 20k per year.[/quote][/quote]

E46 is single clutch.

E60 M5 and the M6 are both double clutch unless the guy that trained me at BMW Braknell HQ was wrong?


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## garyc (May 7, 2002)

Tubbs said:


> garyc said:
> 
> 
> > BMW and Porsche are both working on their own twin clutch systems after success of VW DSG in Golf and Veyron.
> ...


[/quote]

E46 is single clutch.

E60 M5 and the M6 are both double clutch unless the guy that trained me at BMW Braknell HQ was wrong?[/quote]

<<The SMG transmission shifts all gears electrohydraulically with all control units operating by wire, that is, without any mechanical connections. Both the SMG hydraulic unit and the gearshift actuators are integrated in the transmission housing. Whenever the driver wishes to shift gears, the control unit activates the appropriate solenoid valves within thousandths of a second, setting the hydraulic system as required. Now the hydraulic fluid under a high level of system pressure of up to 90 bar is able to flow into the clutch master cylinder within fractions of a second, opening *the clutch *in the process. This, in turn, serves to activate four hydraulic cylinders in the gearshift actuator controlled by solenoid valves in the hydraulic unit. The four hydraulic cylinders then serve ultimately to shift the gears by way of four separate gearshift rods. And when down-shifting, the engine automatically "blips" the throttle between gears.>>

..from BMW literature.

Either he was wrong or you werent paying enough attention.
:wink:


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## PaulS (Jun 15, 2002)

As I understand it, DSG is the only gearbox system that uses twin clutches, thus can provide seamless transition between gears. In effect, two gears are engaged at once, the clutches slip during the change. High level of electronics and computing controls the system.

SMG is a Manual box - but with electronics controlling the changes. I think it has a clutch though :?, so it's only one gear at a time. Changes are very jerky under heavy load as I witnessed as a passenger at a Bedford track day.

Old school auto's were all based around torque converters and hydraulics and are no good for sports driving, Affectionally known as slushboxes, their best application being in large luxobarge saloons. Massive time delay between changes and the torque converter saps energy too.

Porsche, and Audi's 'tiptronic' are electronic versions of the slush box, and are crap imho. Had it in the Boxster and immediately regretted it.

If I decided on an auto, my choice would be the DSG, which I understand Porsche will be fitting to the 911/Boxster/Coxster soon.

But at the end of the day, if you want an involving drive, forget autos and just use a manual instead. Even though these new boxes can change gear "in a fraction" of a second (sometimes up to 2 seconds in bad ones...) during that period you are waiting for the car to react, whilst with a manual you are engaged in driving the thing and it's not a problem! OK on a track lap times might be better with DSG/SMG but for real world driving there is no real benefit imo

Manual any day for me 8)


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## raven (May 7, 2002)

Out of interest, does the SMG gearbox change down to prevent stalling if you slow down in say 4th gear and forget to change down manually?


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## omen666 (Oct 10, 2004)

Yes

But it won't change up in the opposite scenario if you in manual mode, you'll just bounce off the rev limiter :twisted:


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## raven (May 7, 2002)

omen666 said:


> Yes
> 
> But it won't change up in the opposite scenario if you in manual mode, you'll just bounce off the rev limiter :twisted:


That's what the DSG should have done. I used to get annoyed at it changing automatically. That's what the rev limiter's for anyway... :roll:


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