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Question about the M3's tranny

2K views 16 replies 6 participants last post by  dennisjai 
#1 ·
hey fellas im a newbie =] can someone elaborate on the differences between a MANUAL Tranny and a SMG Tranny (Sequential Manual Gearbox) for the BMW m3?

thanks
 
#2 ·
First off, welcome to the forums :welcome

The manual transmission has 6 gears plus reverse, and from what I hear its clutch is a little heavy, but the car is after all, high performance. The SMG tranny only has a reverse, neutral, and +/- gears. The +/- gear has 2 modes, Sequential and Automated. The sequential mode has 6 drivelogic programs which are different transmission programs that control shift speeds, ideal shift point, and so on. In this mode, you may use the lever or the paddles on the steering wheel to change gears. The right paddle upshifts, the left paddle downshifts. The automated mode has 5 drivelogic programs, which act the same way as the sequential program in that they both control shift speeds, and shift points, and so on. However in automated mode, the SMG system shifts the gears for you kinda like an automatic. The one big difference between the Steptronic Automatic Gearbox and the SMG, is that the Steptronic Transmission has a torque converter which "eats" horsepower" and does not have a true electronic clutch like the SMG system.

Which one is better you ask?? I'd go for the SMG because of the unbelievable fun you will have driving like an F1 driver, and because of its lightning fast shifts in Sequential Mode 6. The SMG also helps in stop and go traffic, because you can just pop the shifter into automated mode and the computer takes care of the rest. However if you want a stickshift and are not willing to fork over the extra 2,400 for the SMG option, then just get stick.
 
#3 ·
i see.. thanks for the very detailed apply although i got confused abit.. did u mean the AUTOMATED tranny that u dont have to do anything eats alot of horsepower?

edit: also the - gear is the one where u change gear by urself
and the + is where it does everything for u?

thanks again!
 
#4 ·
did u mean the AUTOMATED tranny that u dont have to do anything eats alot of horsepower?
No, the SMG transmission does not have a torque converter which eats a lot of horsepower, regardless of what mode it is in. An automatic transmission with park, rever, neutral, drive, has a torque converter and that eats up HP.

edit: also the - gear is the one where u change gear by urself
and the + is where it does everything for u?
No, the - on the lever is used to downshift, and the + is used to upshift. To change from sequential to automated mode, you would nudge the gearshifter to the right, let me draw you a diagram...

®
|
(N)__(+/-)-o

® = reverse gear
(N) = neutral gear
(+/-) = Upshift or Downshift
o = Change transmission mode

If you still don't get it, check out SMG and then click on SMG Drivelogic
 
#7 ·
and an interesting thing: how to launch:
stop. push the shifter forward and hold it there... rev to 3500 i think and let back into the normal position (the shifter that is)
 
#11 ·
thanks all for your help now i just wanna get the AUTO part fully correct
on the BMW website you have this bar thing as shown on the picture below
so i guess you click the button to change style like if u wanna drive eco or sporty or full power?

edit: so can like someone explain from gear 1 - 5 or was it 0-5 i dunno but can someone explain those gears a bit as the website isnt so clear
 

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#12 ·
thanks all for your help now i just wanna get the AUTO part fully correct
on the BMW website you have this bar thing as shown on the picture below
so i guess you click the button to change style like if u wanna drive eco or sporty or full power?

edit: so can like someone explain from gear 1 - 5 or was it 0-5 i dunno but can someone explain those gears a bit as the website isnt so clear
I think you're referring to the drivelogic programs not gears. In automated there are five programs, right below the shifter, there is a button that looks like this:

\/ [][][][][] /\ the \/ arrow selects a lower program, while the /\ arrow selects a higher program. Program A1 (Automated 1) has slower more economic shifts, and is basically for neighborhood driving. Higher programs like A5 (Automated 5) provide faster shifts like when you wanna go on a highway and don't want jerky shifts.

As for launch control, here is the step by step:
Step 1: Stop the car completly, no acceleration or movement. Turn off DSC and choose sequential mode 6.
Step 2: Pull the left paddle on the steering wheel OR hold the shifter in the - position
Step 3: While - is held down, fully open your throttle (gas all the way down)
Step 4: The RPM will automatically go to 4,500 RPM in cars with the European software, but with the US software, i believe it is lower.
Step 5: Release the shifter from the - position (or let go of the paddle) and keep the gas pedal fully depressed. Be prepared to upshift since the car will violently accelerate.
Note: If you have the US software installed, doing this more than twice will void your warranty, so try to get the dealer to install the European software and do this to your heart's content, but be sure your engine is broken in (has a few miles on it).

Hope this helps, B)
 
#13 ·
Are you sure that doing this twice will void the warranty? According to this Popular Science article, it is illegal to void warranties on something like this, which is why the RPM limit is only ~1800 on US software:

But there is a catch. In Europe, where the feature isn't so hush-hush, doing more than 15 launches voids the car's warranty. Federal laws prohibit such stipulations here, so BMW has turned down the wick. U.S.-spec cars are programmed to wind to only 2,500 rpm—and our test car topped off at 1,800. That's why you have to ask your dealer to install the European software. Most will happily oblige.
http://www.popsci.com/popsci/auto/article/...,358540,00.html

I hope you're wrong 'cuz I've done it about 6-7 times. :blink: (It's really fun, btw)
 
#15 ·
Another correction: This hard launch does NOT work from the paddles. Only from the stick.
Not too sure about that, have you tried it???
 
#17 ·
hehe smg is so confusing they should just add a regular automatic because a luxuryish sport cars are my fav like the g35 and i'd say its more fun to drive a auto instead of having to shift up and down 24/7 i'll probably get like a older subaru for that =p
 
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