SMG Steptronic Automatic Manual question

Would anyone please explain the basic differances between these 4 transmissions. I am having the most difficulty between the SMG and steptronic. They seem to be the same thing, but I think there actually is a differance. Manual would be the only one with a clutch, right? How is shifting differant between steptronic and SMG? I appreciate anybody taking the time to explain this. Thanks a million.

Automatic is automatic. (use torque converter to connect between engine and drive train) I guess this one is self explanatory.

Steptronics is automatic, just a different name used by BMW. It has one feature, where you and use the +/- in the shifter gate to change gear yourself. A lot of automatics today has this features tho.

Manual is "stick shift", use clutch plate to connect engine to drive train. Driver have an additional clutch padel to operate compare to automatic. This should be self explanatory too.

SMG is a manual transmission with a computer controlled clutch, so drivers don't need to operate the clutch.

eel

Okay, but which is better: manual or SMG?

Alex

Originally Posted by BahnBaum

Okay, but which is better: manual or SMG?

It's all down to personal preference. You have to drive them both and see which you like better. SMG is technically "better" since it shifts faster and you can't miss a downshift and blow your engine. However, manual is "better" since it's a more involving driving experience.

My take is:

Step is the most comfortable and convinient.

6 speed manual is the most fun but need more work from driver, and inconviniet if stuck in traffic.

SMG is the compromise of both, while operate like a step, but does not sacrafies power like step. But missing a padel cut the fun into half, and sure not as comfortable and smooth as Step. Performance wise, I think SMG is better than Step, and should be better than average driver. I think good driver will beat SMG in 3 series.

Also, I have heard someone said "BMW means 3 padels". I tent to agree with that.

eel

Gosh. You guys are so serious. I was just kiddin' when I asked which was better!

Alex

Originally Posted by drbmw

Would anyone please explain the basic differances between these 4 transmissions. I am having the most difficulty between the SMG and steptronic. They seem to be the same thing, but I think there actually is a differance. Manual would be the only one with a clutch, right? How is shifting differant between steptronic and SMG? I appreciate anybody taking the time to explain this. Thanks a million.

I think you basically got it from Eel.

I am no Mechanical Engineer, and what follows may be a load of old smelly rubbish, but here's my 0.02, YMMV:

The engine is the same, right? And since the rear of the car is driven from the propshaft (connects transmission to the "gearbox" in the rear usually called the differential, converts rotating energy 90 degrees to the driveshafts driving the rear wheels.

The thing in the middle is the transmission.

As eel said, "standard" transmission uses a friction plate and a pressure plate to disconnect(clutch in) and connect (clutch out) the transmission to the prop shaft. When the clutch is in (disconnected) you can select a different gear between the engine and the prop shaft with different number of teeth. Each gear is selected to run at a different ground speed with the same range of engine speeds, but you will get more torque (twist) out of a lower gear (say, 1st) than a higher (6th) gear. When the clutch is out, and the car is "hooked" up, there is a direct connection from engine through transmission to propshaft.

Standard cars will have three pedals, clutch, brake, accelerator.

"Automatic" or (BMW's) Steptronic are basically different names for a transmission that "shifts" by itself. An auto uses internal clutches and fluid coupling packs to switch gears based on engine load, rpm, etc etc. Some auto's allow the user to 'hold" gear up or down, or provide a limited range of "shifting". Unfortunately for an automatic to function there must usually be a certain amount of "slip" allowed i.e. you stop at a stoplight and just put your foot on the brake. This is allowed by a device called a "torque converter" which is basically two shafts with vanes connected inside a fluid-filled cavity. When one shaft starts to turn, it starts to spin the fluid, which induces torque (hence, "torque converter") in the other output shaft. There is a certain penalty you pay in this in drive shaft in/out efficiency i.e. the output shaft cannot turn at the same rate as the input shaft and hence the TC will have a mechanical loss of a few percent.

Automatic cars have two pedals, brake and accelerator.

SMG or Sequential Manual Gearbox is a standard gearbox, with an internal, electrically or hydraulically operated clutch. Its basically a standard gearbox in which the car, through very clever electronics, operates the clutch for you. They have "auto" modes in addition to "manual" modes but these are not as smooth as "regular" automatics.

Oh yeah, and welcome to the 'fest

I thought we don't have the same SMG tranny as M3..
but anyway, does anybody know how fast the SMG tranny can do on 325/330?

Thanks!

Originally Posted by euroPower

I thought we don't have the same SMG tranny as M3..
but anyway, does anybody know how fast the SMG tranny can do on 325/330?

We do and we don't. The non-M SMG is the same basic mechanism as SMG II (which is what BMW calls the ///M SMG). But there are differences. I think the non-M SMG is made by Magneti-Marelli (which makes the Ferrari SMG-type tranny), whereas SMG II is made by Getrag. Also, non-M SMG only has 2 or 3 modes, but SMG II has 11 or 12 different modes. Also, SMG II has an interesting anti-rollback feature (can't remember what it is called), which allows you to shift from a dead stop while on an incline without rolling backward into the car behind you.

As for performance, from what I understand, the non-M SMG shifts in ~150ms, whereas SMG II shifts in a mere ~80ms. At 80ms, I think it would be difficult for any but the best manual drivers to shift faster than an SMG II driver. But at 150ms, the shift speeds are much more comparable. The average driver probably couldn't shift in less than 150ms, but some of the drivers on this board likely can, especially those who track.

So, any manual drivers out there actually know how fast they shift?

I have heard two different things on the manufacturers of the sequential systems.
1. M3's SMGII made by Siemens, 3er's SMG made by Magnetti-Marelli
2. M3's SMGII made by Siemens, 3er's SMG also made by Siemens, but SSG available in some parts of the world made by Magnetti-Marelli. The reasoning for this was that to call it SMG when it was made by MM would be copyright infringement, therefore it must be made by Siemens. The UK and parts of Asia get the MM made SSG unit.
Anyone have the definitive answer.

Originally Posted by cronimi

As for performance, from what I understand, the non-M SMG shifts in ~150ms, whereas SMG II shifts in a mere ~80ms. At 80ms, I think it would be difficult for any but the best manual drivers to shift faster than an SMG II driver. But at 150ms, the shift speeds are much more comparable. The average driver probably couldn't shift in less than 150ms, but some of the drivers on this board likely can, especially those who track.

So, any manual drivers out there actually know how fast they shift?

Blah, there is no way a human being can depress the clutch, select the next gear, then release the clutch in anywhere near 150ms, that is less than a quarter of a second.

Any chest thunping manual driver who thinks that he can is smoking some really good stuff.

I have been spoiled by the SMG in the M3, and yes, I think that the SMG in the non-M car sucks. Heck, if Porkchop had a system as good as the SMG on my old M3, I would not have hesitated in getting in. I have a 6 speed Turbo, but honestly, while I can heel and toe and rev match, those acts do not turn me on. And on the track, I much prefer SMG (when it's done right).

Originally Posted by eelnoraa

6 speed manual is the most fun but need more work from driver, and inconviniet if stuck in traffic.

traffic doesn't bother me with a manual. it's the same whether i drive the automatic I30 or the 330Ci...

i always thought the whole 'traffic' excuse is a copout by those who want to make it appear like they considered getting a manual but decided on the auto because of traffic, when the truth is they never ever considered a manual in their wildest dreams.

Originally Posted by Matthew330Ci

traffic doesn't bother me with a manual. it's the same whether i drive the automatic I30 or the 330Ci...

i always thought the whole 'traffic' excuse is a copout by those who want to make it appear like they considered getting a manual but decided on the auto because of traffic, when the truth is they never ever considered a manual in their wildest dreams.

Yeah...I used to only drive manual trannys....

Then came cell phones, palm pilots, navigation screens, etc etc. I'm too busy in my car to use both my hands to drive......call it my "excuse"....I love driving my Step and I'm still having the Utimate Driving Experience........stop judging.

Originally Posted by MARCUS545

Yeah...I used to only drive manual trannys....

Then came cell phones, palm pilots, navigation screens, etc etc. I'm too busy in my car to use both my hands to drive......call it my "excuse"....I love driving my Step and I'm still having the Utimate Driving Experience........stop judging.

Ultimate Distraction Experience is more like it.





seriously, i wish people would actually drive when they're driving, instead of the myriad of other activities such as yacking on the phone, eating a big mac, putting on make up, reading a book (I saw this a few times!!) etc.

Originally Posted by Matthew330Ci

traffic doesn't bother me with a manual. it's the same whether i drive the automatic I30 or the 330Ci...

i always thought the whole 'traffic' excuse is a copout by those who want to make it appear like they considered getting a manual but decided on the auto because of traffic, when the truth is they never ever considered a manual in their wildest dreams.

Every car I've ever owned has been a manual, but I honestly hated it in city traffic. I would sit there and wish I had my mom's car w/ me so I wouldn't have to deal w/ the clutch...etc. It's not the worst thing in the world, but rather annoying and sometimes hard to keep from riding the clutch during those slow rolling traffic jams. I LOVE a manual when it's time to get out in the twists or in snow. I always drove my parent's automatics like manuals when the weather was crappy. Engine breaking can be a bonus sometimes. If I end up being able to order this M3 this fall then I'm going w/ the SMG. No, I've never driven the SMG, but I know I want the "best of both worlds."

E46 M3 has SMG II. E46 non-M has SMG, which is SSG in Europe.

SMG II is by Siemans and BMW, SMG/SSG is by Magnetti Marelli.

SMG II has 11 modes of operation, SMG/SSG has 2 or 3.

I disagree that SMG II is less involving than a manual. I have both, and have driven manuals for a LOT of year and miles. In fact I have never owned a car with anything other than a manual. SMG II is very involving, but in a different way. I find it just as satisfying to drive on the street, and positively AWESOME on the track. Until you have spent time with an SMG II car, you are just quessing at what the experience is like.

The one thing about automatic/Step that people did not fully explain is the torque converter. On a manual or SMG you have a flywheel that has a pressure plate attached. The pressure plate is a flat surface with springs. In between the two is the clutch disk, which is attached to the transmission. When the clutch is engaged (pedal out) the springs in the pressure plate clamp the clutch disk between the pressure plate and the flywheel sending power to the transmission without any loss. WHen the clutch is disengaged, you use your mmuscle power to act against teh springs to remove the clamping pressure to all the flywheel and clutch disk to opeerate independantly.

A torque converter is a fluid drive. If you take two fans and face them at eash other, and turn one on, the other begins to turn due to fluid coupling. A torque converter is like the two fans, but instea of air, it uses hydraulic fluid (or Automatic Transmission Fluid) to couple the two fans. This is how power is transfered. And just like the two fans, if you reach in and stop the second fan (the one being turned by air movement) it doesn't affect the fan that is turned on. So at any time you can have the transmission turning at a different speed than the engine.

Inside the case a manual transmission has simple gear sets, one input, one pout for each gear you can select (reverse has a third gear to reverse the rotation). Automatic transmission use planetary gear sets, which has small gears running inside a track made up of a large gear with the teeth on the inside. Auto transmissions use internal clutches to switch gears.

Most modern auto transmission also have a clutch like a manual, but smaller to "lock up" the torque converter while cruising. A torque converter wastes power in the fluid under all conditions, and that wasted power means high fuel consumption. So the lock up clutch allows the engine to drive the transmission without loss while cruising. You have no control over this clutch.

Originally Posted by BahnBaum

Okay, but which is better: manual or SMG?

Silly question....everyone knows SMG is better

From a non-enthusiast user standpoint, SMG and Steptronic are virtually identical. Both will shift for you when you want them to and both allow you to "manually" shift them should you choose to. The mechanicals behind both are VERY different and the SMG will perform that manual shift many times faster. But, purely from a user perspective, they are much more similar to each other than either is to either a true manual or an old-school automatic.

Of course, many enthusiasts refuse to see their beloved SMG in this light.

Originally Posted by Matthew330Ci

Ultimate Distraction Experience is more like it.


seriously, i wish people would actually drive when they're driving, instead of the myriad of other activities such as yacking on the phone, eating a big mac, putting on make up, reading a book (I saw this a few times!!) etc.

Originally Posted by TD

From a non-enthusiast user standpoint, SMG and Steptronic are virtually identical. Both will shift for you when you want them to and both allow you to "manually" shift them should you choose to. The mechanicals behind both are VERY different and the SMG will perform that manual shift many times faster. But, purely from a user perspective, they are much more similar to each other than either is to either a true manual or an old-school automatic.

Of course, many enthusiasts refuse to see their beloved SMG in this light.

Have you actually driven an SMG equipped car? If not then I don't think your opinion on this MATTERS.

No offense, but you're formulating opinion on something you've NEVER tried. Go drive one and you'll see just how "different" the SMG is to an automatic.

Originally Posted by TD

From a non-enthusiast user standpoint, SMG and Steptronic are virtually identical. Both will shift for you when you want them to and both allow you to "manually" shift them should you choose to. The mechanicals behind both are VERY different and the SMG will perform that manual shift many times faster. But, purely from a user perspective, they are much more similar to each other than either is to either a true manual or an old-school automatic.

I can't say if this is true with the non-M watered-down SMG (SSG), but any non-enthusiast driver who thinks the SMG is "just another automatic" is going to be disappointed. I've heard comments like "that's the worst automatic I've ever driven", etc. OTOH, if you treat it like a clutch-less stick, it's great. I am waiting for an M6 coupe w/ SMG.

Originally Posted by The HACK

Have you actually driven an SMG equipped car? If not then I don't think your opinion on this MATTERS.

No offense, but you're formulating opinion on something you've NEVER tried. Go drive one and you'll see just how "different" the SMG is to an automatic.

I tent to agree what TD has to say. I got Z4 SMG as loaner when I drop off my car for alarm activation and key programming. To me, SMG and step is not too much diifferent for daily use. Anything SMG can do, a step can do, in a slower and more comfortable fashion I supposed.

Mechanically, they are very different, but this is not like something that everyone will care. (I know some people will). I guess if I take it to track, I will see more advantage of SMG, but not during daily commute.

Also one comment, you know SMG in other countries is less expansive than Step. Only US has the pricing opposite. I wonder why!!

eel

Originally Posted by The HACK

Have you actually driven an SMG equipped car? If not then I don't think your opinion on this MATTERS.

No offense, but you're formulating opinion on something you've NEVER tried. Go drive one and you'll see just how "different" the SMG is to an automatic.

Jon Shafer has already posted (some many months ago) agreeing with my assessment. While enthusiasts don't want the two considered to be anything alike, in general, the market (of real buyers) sees SMG as a fancy automatic.

Ok, thanks to everybody for their input. One area that wasn't addressed was how shifting proceeds in an SMG. I kow that in a steptronic you can onlyshift from one gear to the next highest gear at a time. You can't jump from 1st to 3rd, for example. What about the SMG? Can you jump gears?

The reason I ask is that in my former 2000 540i 6 speed, I would often downshift from 5th to 3rd, for exampe, while coasting to a red light. It was cool having the ability to choose exactly what gear you wanted without necesssarily having to go up or down in sequential order. That made the manual sweet to operate. With SMG, if you're at 70 mph and coasting to a red light 1/2 mile ahead, will you have to in the manual mode, make sure to downshift all the way? It would be pretty awesome if you chould choose to skip gears in this scenario.

Just wondering. Thanks

when you downshift by two gears with SMG it is actually hitting both gears, not just skipping over one and to the next. It does it fast enough though,(I don't think it lets the clutch out in the gear you want to skip) that it feels just like skipping a gear.
When you are coming to a stop it will downshift for you, but it only goes into first when you are going very slow.