3 series with AT?

"Zarnold Edward Quigley" wrote

I suggest you visit the

Pete

"Zarnold Edward Quigley" wrote

Automatic transmissions are extra-cost options on all BMWs (other than the 7 series). It's usually around $1200. You also usually have the option of a sequential manual gearbox - a manual with computer controls.

FloydR

Try

Only on a few - and just the M3 in 3 Series? Unless you mean Steptronic which is merely a slightly more sophisticated selector for the auto and not really worth the extra.

BTW, the SMG isn't a manual. It is an auto, but based on a synchromesh box rather than an epicyclic.

You're right - they are not (yet?) available in the 3-series. The 5-series has it as an option on the I6 models, so it's probably only a matter of time. All M-models have one available.

Since the middle word of the acronym is MANUAL, that directly controverts your position. Enough.

FloydR

Purely adspeak to convince those who can't cope with a clutch they're 'driving' a real gearbox. It's an auto pure and simple - unless you think of any manual box that can change gear by itself. And controls the engine speed and clutch during gearchanges.

On 6/21/2006 1:46 PM, Dave Plowman (News) went clickity-clack on the keyboard and produced this interesting bit of text:

It's my understanding you can use it in full manual. Is this not so?

"Voinin" wrote

What's your definition of "full manual"? If by that you mean having a clutch pedal on the floor, then I don't believe the SMG has one, and it won't let you shift from 4th to 2nd directly either - you'll have to tap it twice. :)

Pete

No. A manual gearbox allows you to do all sorts of daft things. Not so an SMG.

I think we all understand that distinction.

The big deal about the SMG is it's made internally like a manual transmission - real gears with changes made by gear-change forks, etc. It uses hydraulic servos to essentially do the motions your shifter hand would do with a manual. And it has an actual clutch on the flywheel. It is as if you had a robot to move the shift lever and push the clutch pedal for you when you don't feel like doing it yourself. OTOH, the traditional automatic transmission design uses planetary gears behind a fluid torque convertor. Internally the two transmission types are completely different. Looking at the internal components of an SMG, you might have a hard time telling them apart from those of a traditional 5-speed from any major manufacturer. Not so comparing SMG internals to a conventional auto trans. I'll take an SMG over either one anyday. If the Jetta TDI was available here with SMG I'd have one right now.

SMG is an option (in the U.S.) only on the 530 & 550, but not on the 525. But one wonders why not the 330, (if not the 325).

Tom K.

BMW's Steptronic transmission is an auto, pure and simple, with which gear selection may be made manually if desired. The SMG is a different animal. It's far from an "auto pure and simple". It's a 7 speed manual transmission that can be shifted in an automatic mode, if desired, controlled by a computer.

BMW's SMG in the '06 M5 does all that you describe above. It's a manual transmission with a clutch that *can* be operated to shift from gear to gear automatically (I rarely use this mode). It is simply missing a clutch pedal. A computer controls the disengagement of the clutch, shift, and re-engagement of the clutch faster than a human is capable of doing. During downshifts, it also "blips" the throttle to match engine RPM to the lower gear. Driving in the highest performance mode ("S6") produces the fastest shift speeds and will convince anyone quickly that it is a manual transmission. When the clutch engages during shifts in this mode you definitely know it ... it's violent.

Eisboch

My wife's car is an '06 750li with the Steptronic automatic transmission. My car is an '06 M5 with the SMG.

I drive them both.

There's nobody on earth that is going to convince me that the SMG is an automatic transmission that you can shift manually. It's a manual transmission that may be operated in a mode that allows the computer to do the shifts for you, if desired. I think I've tried it twice since I got the car. Yuk.

Eisboch

Which is a better way of making an auto. However, you don't *need* the torque convertor, and modern multi ratio autos make little use of it. It's also perfectly possible to have *total* manual control over a 'conventional' auto, and for the shifts to be as fast as any SMG type.

Try telling that to a garage when you ask them to fix an SMG transmission. Basically, they can't, unlike a manual.

Rough changes and all? I'd be ashamed if I produced such poor shift quality on a true manual when driving it gently. Of course the twin clutch types are better - but BMW don't use them yet.

Err, I'm perfectly aware of the mechanics of both types of auto, and any box which changes gear by itself is an auto - regardless of the internals. A manual box is err manual - shifted by hand. That's what manual means...

Exactly. It's a mechanical abortion.

You mean, besides every single time you bring the car to a stop? The torque converter, among other things, is what allows you to stop the car without putting the transmission in neutral.

It also expands the gear ratio ranges so that you get smooth performance with fewer gears. Three and four speed auto boxes work just fine for most things...three and four speed manual boxes almost always suck.

Tom.

Older autos used a fluid flywheel which doesn't waste as much energy as a TC. However, a TC which locks up via a clutch once the car is under way is much the same thing - its main job on a multi-speed auto is simply to cushion the gear changes. You could, if needed use a servo operated dry clutch for this - same as a SMG does. A TC isn't intrinsic to an epicyclic gearbox.

Three speed autos with a torque convertor *may* work ok after a fashion with a big lazy engine but you pay dearly in fuel use since a TC isn't as efficient as gears. IMHO, 5 is the minimum for an auto as a manual if you want decent performance and economy.

I can see your mind is made up. Ok. No problem. Question though. Have you driven an M5 or M6 with the latest SMG? I am just having a problem with your statement that it is "an auto, pure and simple."

IMOH, it does exactly what it is supposed to do. The "violent" shift in S6 is by design, not by design flaw. If you want smooth, lazy shifts you can use S1 or S2.

Eisboch

This is one of Mr. Plowman's semantic arguments, and I have to say that I am forced to agree with him.

'Automatic' has in common parlance become synonymous with an epicyclic gearbox/torque converter transmission and 'manual' has become synonymous with mainshaft/layshaft movable gears and dry clutch one.

What those definitions are missing is the means by which gears are shifted. If it can do it by itself, it's automatic. If you must do it, it's manual. Regardless of the underlying mechanicals. That's Mr. Plowman's point, the one he keeps hooking all you fish with.

I had a Citroen DS19 back in the late 60s, with a little electrical lever/switch on top of the steering column that changed gears. Moving the lever automatically disengaged the clutch, changed the gear, and re-engaged the clutch. It wouldn't change gear unless you moved the lever. The clutch operation was completely automatic, there was no clutch pedal. Do you think it was an automatic or a manual transmission? Either way, it was a hoot, and one of the most memorable cars I've owned.