Originally Posted by madfast

i'm no sst/dsg/dct expert or anything like that but this sounds wrong. it'd be the case if you're talking about a true sequential manual like the ferrari f1 tranny but the SST is a dual clutch. gears 1,3,5 are on one shaft and 2,4,6, on another. so to go from 6 to 2 it DOESN'T have to go through every gear to get there. it simply has to go from 6 to 2. the problem however is that the next gear on the other shaft is preselected. if you slow down and then plant the throttle, the computer gets confused and it may need to deselect the next preselected gear for a situation that it didn't expect given the parameters that it monitors.

EDIT: i reread the original post that talks about the delay and this only happens in normal mode. that's because only in normal mode does the SST skip gears. in supersport and sport modes it will act like a true sequential and row thru all the gears. why? exactly for this reason, no delay in power.

if you're in 4th and start braking, it will preselect 3rd. step on the gas and depending on rpm it may either stay in gear or drop down to 3rd for a bit and then go back up to 4th. in normal mode, depending on how they programmed it, it may preselect a much lower gear like from 4th to 1st. when you step on the gas you really need 3rd so the tranny has to disengage 1st (the "wrong" preselected gear), engage 3rd (the "right" preselected gear cuz you all of a sudden pressed the gas again), disengage the clutch on shaft 2,4,6 and engage the clutch on shaft 1,3,5. all this for a simple downshift to the next lower gear? YES!!!

THIS IMO causes the delay in normal mode. the preselection of the next gear is all based on fuel economy and well... NORMAL driving. if you want uninterrupted power, use sport mode always.

for evidence look a this video where BM does 0-400m runs in all 3 modes.

http://youtube.com/watch?v=ZvSvN5ja884&feature=related

in s-sport and sport modes, even when the brake is fully depressed, the SST will row thru all the next lower gears to get to 1st. in normal mode, the gears go from 5th to 6th (an upshift on decel!!!) back to 5th then 2nd (totally skipping 4th and 3rd) then 1st.

Originally Posted by Ridge Racer

This is a true sequential transmission, not act like, it is. It just has an option not to be. My motorcycle comparison was just to show that this tranny is comparable to one in the way it shifts, and to stress the point its not an automatic with a torque convertor. Where did you find that it skips gears in normal mode? I been reading everything that comes up about this car since the unvieled it at SEMA I never saw anything like that to date. Read this link below, I got more if anyone wants to see them.

Originally Posted by Ridge Racer

Also read this page, you'll see it is like the one you use on a motorcycle or a race car. The differance in the ferrari tranny and this one is... The ferrari has one clutch and one tranny. In the SST what you really have is two 3 speed trannies and 2 clutches. You still can't skip a gear like you think. Each gear box will have to move down to the next gear in its selection. Now I'm not saying that the computer can't or want not go from 6th a differant gear than 5th, I'm saying each tranny must move to the next gear in its order. If this doesn't make sense tell me.

Originally Posted by madfast

it is NOT a true sequential. it can skip gears. motorcycles can NOT. the ferrari f1 sequential tranny can NOT.




no you are wrong. the engagement of both clutches and the engagement of gears is electronic. by virtue of having two shafts you can skip gears. for instance if i'm in sixth, i could have programmed the twin clutch to preselect 1st, 3rd, or 5th on the other shaft. i could even program it to skip the other shaft altogether and have the clutch disengage and select either 2nd or 4th and then re-engage the clutch. this of course would destroy the purpose of having 2 shafts/clutches and would be very slow.

please view the link i posted and watch the 0-400m run in normal mode. at the end when they brake you can CLEARLY see the SST skip gears. don't listen to me, listen to what your eyes see. ooh that rhymed

Originally Posted by USP45

Ridge Racer you are flat wrong man. There is a scematic for the SST running around somewhere. The SST is not a stacked design like a motorcycle tranny, you DO NOT have to go through all of the gears when going from 6-2 or vice versa. And a sequential tranny like in a motorcycle and a Ferrari or BMW are not secissarily sequential in the same way a motorcycle is to, some SMG's are automated manuals, not true sequential tranny's. And don't believe everything that you read on Wikepedia...

Originally Posted by Ridge Racer

Reread what I wrote again, I never said it couldn't skip gears, I said each of the seperate 2 trannies can't skip gears, I don't think I am wrong. I think you still don't understand there are like 2 three speed trannies spliced together and that each one operates separatly.

Originally Posted by madfast

you asked "Where did you find that it skips gears in normal mode?". i posted the youtube video that proves that it does.

i fully understand that the tranny acts as two 3-speed trannies. what you seem to not understand is that each 3-speed tranny is not a true sequential tranny. by true sequential i mean any tranny that cannot physically skip gears. in motorcycle engines and other auto sequentials, the tranny uses a ratchet type mechanism to turn an up/down motion into an H-pattern. now i dunno for sure if the ferrari f1 tranny can physically skip gears but i doubt that it still uses this ratchet system. it may be that ferrari just programs the tranny to not skip gears so as to be as "F1-like" as possible. if someone knows for sure, chime in. my guess is that it's not a true sequential as it can skip gears if programmed to, but they don't?

what i DO know is that DCT's use electro-hydraulic activated shift forks to switch gears. so depending on how you program the tranny, ANY gear can be engaged at ANY time on the other shaft. which gear to select of course would depend on the parameters set. if you're in 6th gear at 6000 rpm and you brake, you could program the SST to physically move the shift fork to engage 1st as the next lower gear, but that'd just destroy the engine. in a motorcycle tranny, you cannot physically get to 1st without engaging every gear in between. there's a big difference between "could but wouldn't" and "can't".

so what we have here is PROOF that the two 3-speed trannies that make up the DCT are NOT sequential trannies. they do NOT use any kinda ratchet system. they have electro-hydraulically actuated shift forks.

DSG proof:

http://www.youtube.com/watch?v=WVWP7TYhP0c

you CANNOT get anymore clear than this video above

SST proof:

http://www.carbuyersnotebook.com/TC-SST_01.gif

notice the "hydraulic unit" activates (green lines) EACH INDIVIDUAL shift fork (rectangle with X).