Aha... there is a Sequential Manual Gearbox (SMG) but their is also a Sequential M Gearbox (SMG) as fitted to the M3 and CSL, ie. with Drivelogic. There is also an SSG, an Automatic and a traditional Manual.
Tell you what, lets all waste another day debating the merits of each.
LOL!!
What a lot of squabbling.
A [fully] manual gearbox as found on most UK cars allows any gear to be selected from neutral and vice-versa. Since about 1948 they have normally incorporated synchro-mesh (small brass cogs with limited friction which help synchronise the main gears when changing). The gears run on keyways and only the cogs of the gear selected are actually in mesh.
A [fully] automatic box uses an arrangement of planet and sun gears, originally to provide three basic ratios (with the assembly locked, with the cage free to rotate and with only the planetary gears free to rotate). A fluid flywheel / hydraulic clutch completes the assembly and allows the car to move off from stationery. The hydraulic arrangement may also provide some flexibility in gearing (torque converter) and a take off of hydraulic pressure to operate the gearbox. More recent boxes have more gears and solenoids can be used to activate gear changes, however the original Borg Warner and Powerglide boxes had no electronics and the box worked automatically changing gear in response to road speed, power and load.
An SMG box is basically a development of the continuous mesh gearbox found on most motorcycles. All the gears are in mesh all the time, and it works by a dog clutches which can select one gear (or none) at a time, the rest simply rotate around the shaft. Its main advantage is lightweight (hence its use in F1), but the disadvantage is that [usually] you have to pass through all the gears to get to neutral (a pain after an emergency stop on a bike). It is a relatively simple matter to automate selection by paddles using solenoids (on a bike the selector is mechanical and usually operated directly into the gear box with the left foot). There is nothing inside the box to make it change gear, so IMHO it is a manual which can be operated [automatically] by electrical means.
Q.E.D. :-)
DAS
For direct contact replace nospam with schmetterling
Coorrr!! I'd love to know if that was said with "authority" or just general knowledge because it doesn't half sound good!
I think I'll just drive the damn thing and enjoy it. But.... the actual, physical gearbox in the M3 is the same irrispective of SMG or not. BMW just got clever and bolted on a "box" to automate the shift.
Quite frankly I don;t care and I'm off on hols driving a "towncar" for a week :-(
That makes no difference. Unless you've got another name for a crash box?
So all epicyclic gearboxes are autos? I've got news for you...
Well thanks for the lecture, but you've missed out the CVT - belt and pulley type. Which is an auto. Many ways to skin a cat.
That's bollox too. They (in this context) all have conventional synchromesh. And all manual gearboxes in recent times are constant mesh - at least for most gears.
Have you ever looked at gearbox design?
That would be servo control. Automation is rather more. Watch my lips. It changes gear by itself, therefore is an auto.
Do you understand the meaning of manual? Or automatic?
Full of holes, unfortunately.
Which makes it an automatic. ;-) Or do you think the internals of the 'box make a scrap of difference?
I hesitate to add to this thread, but if what you say is true, why wouldn't anyone make a truly Sequential Manual Transmission with a foot operated clutch, much like a motorcycle's sequential transmission has a hand clutch?
That actually might be quite attractive to the sport drivers... I mean, after all, the weak point of having a 5-speed manual transmission has always been the 2-3 & 4-5 dogleg shifting. That is where all the missed shifts happen with the attendant valve bendage.
It would be easily done.
Which is why they made SMG autos for those who can't handle a true manual box and clutch. ;-)
Yes. Shame it has so many technical mistakes. I'm no expert on gearboxes, but I've had enough of them apart to know that much of his detailed explaination is cobblers. How synchro units work for just one example. Mike.
Obviously you have your cemented-in opinion while the rest of the world differs with you. That's your choice. Sure, it changes gears automatically, but it's a completely different mechanism. Calling it an automatic transmission only muddies the waters. It's a matter of accuracy, not a matter of not acknowledging that it changes gears automatically. When somebody says it's not an automatic transmission, people are saying it's not a slushbox with planetary and sun gears that are involved and that's why people don't call it automatic.
Something to think about....
Do you put ATF > >
Plenty of pure manual boxes use ATF, so that's no guide.
You use grease in a transmission?
An automatic transmission is one which changes gear by itself. Regardless of how it achieves this. Epicyclic, belt and pulley, or robotised manual box.
Nor does a torque convertor enter the argument as these have been used with manually selected gears/ conventional synchro box. And it would be possible to make an epicyclic auto with a conventional servo operated clutch instead of fluid drive.
The CVT is different. I wouldn't call it an automatic or a manual, in the popular application of those words. It's something different.
It's an automatically controlled manual transmission.
You could have a manually controlled automatic transmission.
We will never agree on the semantics. I say that the world uses the term "automatic transmission" to mean a gearbox using a hydraulic link to transfer power, whether it's shifted by the user or by electronics. I say that a maual transmission is one that uses a clutch, whether shifted by a computer or by a human. I classify oddities such as CVT's and centrifugal clutches as specialty transmissions and would use specific words such as "sequential manual gearbox" or "continuously variable transmission" to desribe such things in a conversation.
You say that anything that shifts for itself is an automatic and anything that is fully controlled by a human is a manual.
We'll have to agree to disagree.
I would ask you, in your lexicon, how do I specifically tell somebody that the transmission in car A is a hydraulic torque converter fluid link type, that has been referred to as an "automatic transmission" by every car sales person and manufacturer for the last 50 years, rather than an SMG, CVT, robot-actuated manual transmission, etc?
-Russ.
Bad choice of criteria, Keith. I put ATF in the 5 speed manual gearbox of my '95 325i as recommended by the manufacturer.
You mean like the ability to 'force' a gear on an auto box?
DAS
For direct contact replace nospam with schmetterling
It's a method of providing torque multiplication and starting from rest for an IC engine. Same as any gearbox although different in operation. But in practice most are 'automatics' since they can be left to their own devices.
Seems to me the term 'auto' has been hijacked in the US to mean just one thing. But if you have automatic AC for example does this also include a slush box somewhere? ;-)
Phew. At last. You've got it in one.
Well, you'll have to re-write dictionaries etc then. Because the difference is pretty fundamental. If a car can go from rest to top speed with no intervention from the driver as regards clutch and gear changing it's an auto. Regardless of any over-ride options.
'Conventional' auto might do? Unless you lived in Holland, where the first locally made autos (DAF) had belt and pulley CVT transmissions?
The man on the Clapham omnibus isn't in the least bit interested in how an auto actually works. He just wants one where you plonk it into drive and it goes.
Just look at what you've started!!!
Please let us know what you go for in the end and whether you think an SMG is an automatic or not!
I'm off to try an automatic Toyota for a week :-)
Hertz don;t do cars with SMG boxes.. "Sorry sir, we have autos and manuals. Whats an SMG?"
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