[c0nstant]

sorry for the novice question, but what exactly is the different between a dual clutch transmission and the sequential? also, what are the pros of both and what are the cons?
i was just curious, any information is appreciated

[AndrewAZ]

They both suck for the street. Learn how to drive a manual or just live with an automatic.. For the track SMG would be best.. Basically SMG is a manual transmission with hydraulics attached to it that control the clutch and shifting via a computer. It is very quick about 60-80 ms shift times, the downside is if you are not redlining it the shifts are slow and laggy along with being rough especially when coming to a stop.

Dual clutch has 2 gear shafts one with even and one with odd gears, to make it simple assume your in 2nd gear and getting near redline well 3rd gear is on a different shaft so its ready to go, so when the car "shifts" gears it more of a handoff from one shaft to another and it basically has no shift time. Its smoother than SMG at up shifting, but the downside is the downshifting, its fine if you downshift from 3rd to 2nd but if you downshift from 4th to 2nd it must disengage that shaft and since its an even gear it does not have the next gear ready so it takes a while at times it cant be slower than a standard auto transmission.


I have owned an SMG car and dont recommend it, its fun at first but very boring after a while and driving around town really sucks.

I have only test driven a DSG car and since I had an SMG car at the time I as not thrilled with the idea of another SMG like system.

[c0nstant]

Originally Posted by AndrewAZ

They both suck for the street. Learn how to drive a manual or just live with an automatic.. For the track SMG would be best.. Basically SMG is a manual transmission with hydraulics attached to it that control the clutch and shifting via a computer. It is very quick about 60-80 ms shift times, the downside is if you are not redlining it the shifts are slow and laggy along with being rough especially when coming to a stop.

Dual clutch has 2 gear shafts one with even and one with odd gears, to make it simple assume your in 2nd gear and getting near redline well 3rd gear is on a different shaft so its ready to go, so when the car "shifts" gears it more of a handoff from one shaft to another and it basically has no shift time. Its smoother than SMG at up shifting, but the downside is the downshifting, its fine if you downshift from 3rd to 2nd but if you downshift from 4th to 2nd it must disengage that shaft and since its an even gear it does not have the next gear ready so it takes a while at times it cant be slower than a standard auto transmission.


I have owned an SMG car and dont recommend it, its fun at first but very boring after a while and driving around town really sucks.

I have only test driven a DSG car and since I had an SMG car at the time I as not thrilled with the idea of another SMG like system.

thanks man, im already a big fan of using a traditional manual transmission and i had a basic idea of how the SMG and DCTs worked, i just needed someones opinion on their performance- especially someone whos driven both. i really appreciate it, thanks a lot

[montreal_bimmer]

SMG kicks ass on the track....

[Eastmeetswest]

I think you guys will be surprised at how well the new sport auto works with the double clutch. How often do you shift from 4-->2 on a daily basis and even that will be such a minute difference. Trust me this new clutch is everything SMG tried to be in the manual department and everything an auto is in the auto department. Perfect auto mode that is smooth as a bmw real auto and quicker shifts, no clutch and smoother manuals shifts than any manual bmw offers.

This is a whole step up than the SMG was and that is why its gone.

[c0nstant]

Originally Posted by Eastmeetswest

I think you guys will be surprised at how well the new sport auto works with the double clutch. How often do you shift from 4-->2 on a daily basis and even that will be such a minute difference. Trust me this new clutch is everything SMG tried to be in the manual department and everything an auto is in the auto department. Perfect auto mode that is smooth as a bmw real auto and quicker shifts, no clutch and smoother manuals shifts than any manual bmw offers.

This is a whole step up than the SMG was and that is why its gone.

so youre saying when bmw finally decides to make DCT a choice itll make the SMG completely obsolete?

[Eastmeetswest]

It is a choice on the 535/550s already-or will be in a few months on the 08s. And yes SMGs will be out of bmw line up atleast.

[c0nstant]

Originally Posted by Eastmeetswest

It is a choice on the 535/550s already-or will be in a few months on the 08s. And yes SMGs will be out of bmw line up atleast.

i hope the offer DCT for the 08-09 3s also, that would be impressive

[FirstClass]

I disagree. I think SMG is in the BMW lineup to stay. Look at Audi, they have wonderful DSG transmission tech and what did they put in the R8? They put a single clutch (R-Tronic) that operates exactly like SMG. SMG is here to stay on the Ms.

[AndrewAZ]

The new SMGIII going into the M3 is a lot different than SMGII that I had. My SA told me SMGIII (in the current M5 and M6) was made as a SMG unit from the ground up so its smoother and quicker, vs SMGII which is basically a retrofitted manual transmission.

SMG is a great system for up shifting and downshifts the biggest weakness I point to is the lack of a clutch paddle that race cars have with sequential transmission. If you had a clutch paddle behind the up and down paddles it would make SMG so much better since when you are say making a right hand turn on the street you can pull the clutch paddle in downshift to 2nd gear without having a rough downshift and be able to release the clutch paddle after you have slowed down and are in mid turn. Also this would be useful when coming to a stop, as of right now SMG unit cluck down the gears when you slow down and when it hits 1st gear you get a nice hard clunk and it makes coming to a stop annoying.

[AndrewAZ]

Originally Posted by montreal_bimmer

SMG kicks ass on the track....

Yes and No.. The paddles get in the way. The only reason paddles work on say an F1 car is because of the tight steering wheel ratio that turn at most 90 degrees lock to lock vs say a street car that has to turn 720 or so degrees lock to lock.