C63 vs BMW M3 DCT vs IS F 8 spd

[DakarYM3]

which transmission shifts faster?

[gobuffs]

2 are autos...does it matter?

[E92M3coupe]

double clutch > AMG speedshift > lexus auto

[Jamdun17]

Its a battle between the IS-F and the m3's DCT, the m3's shift speed should be at .2 or so while the IS-F claims .1,(which is very believable if you actually hear that thing shift), who knows but either way the m3 is faster in an actual race, so the shift time is really no factor in this case.

[E92M3coupe]

Its a battle between the IS-F and the m3's DCT, the m3's shift speed should be at .2 or so while the IS-F claims .1,(which is very believable if you actually hear that thing shift), who knows but either way the m3 is faster in an actual race, so the shift time is really no factor in this case.

lol

what u mean by IS-F claims 0.1?

M3 claims MDCT 0.2sec faster than it's manual.
But IS-F doesnt have manual and so doesnt have 0-60mph time for manual IS-F. then where is that 0.1sec come from?

[E92M3coupe]

lexus auto is just a traditional automatic, it does shift fast, but response are very slow.

there is no manual for C63 and IS-F, so hard to say which is better
BUT, as a matter of fact, we know that Mdct is 0.2sec faster in 0-60mph than it's manual. Where C63 we dont know it's 0-60mph comparsion, but we know its shifting speed is 35% faster than NON-AMG benz automatic transmission. and the other non-amg benz automatic that we can compare to it's manual are basically match in 0-60mph time.
so we can conclude that AMG speedshift are 35% faster than it's manual, but dont know 0-60mpg diff. i say around 0.1-0.2 sec. Therefore AMG speedshift are likely same shifting speed as Mdct, maybe a lilbit slower. But forsure faster than lexus auto

[DakarYM3]

lexus auto is just a traditional automatic, it does shift fast, but response are very slow.

there is no manual for C63 and IS-F, so hard to say which is better
BUT, as a matter of fact, we know that Mdct is 0.2sec faster in 0-60mph than it's manual. Where C63 we dont know it's 0-60mph comparsion, but we know its shifting speed is 35% faster than NON-AMG benz automatic transmission. and the other non-amg benz automatic that we can compare to it's manual are basically match in 0-60mph time.
so we can conclude that AMG speedshift are 35% faster than it's manual, but dont know 0-60mpg diff. i say around 0.1-0.2 sec. Therefore AMG speedshift are likely same shifting speed as Mdct, maybe a lilbit slower. But forsure faster than lexus auto

can you explain what's the difference between "shifting fast" and "response"?

i mean, how can a car shifts fast but responds slow? jsut curious. thank you

[Jamdun17]

i think i can help him out with that, the response can be the initiation time (the time between you pressing the paddle to the computer registering it) and the shift time could be the time it takes to change gear ratios, take the IS-F into effect, .2 intiation time and .1 shift time (according to Edmunds inside line) think of it this way, your computer takes a certain time to load a software vs how fast the computer runs the sofware

[Kevlar]

The Lexus IS-F automatic is anything but traditional with a torque converter that can be disengaged as necessary and with 8 speeds it offers supremely close gear ratios to keep the car moving.

The M3 DCT is a new monster and promises great things from what I've been told from people who have driven it.

Mercedes automatic tramissions are some of the best in the world and often can live up to their manual transmission counterparts quite easily.

[GotBHP?]

Its a battle between the IS-F and the m3's DCT, the m3's shift speed should be at .2 or so while the IS-F claims .1,(which is very believable if you actually hear that thing shift), who knows but either way the m3 is faster in an actual race, so the shift time is really no factor in this case.

The M3's clutch disengagement to clutch engagement is 8 milliseconds. Thats .008 seconds. There really is no comparison between that and any torque converter transmission out there in terms of shift times.

[M3roar]

can you explain what's the difference between "shifting fast" and "response"?

i mean, how can a car shifts fast but responds slow? jsut curious. thank you

The thing is the whole Gas OFF and Gas ON thing. Yes the tranny shifts hecka fast but how fast does it let the Gas ON again. Basically the M3 is faster not only for shifts. But also for the Gas OFF/ON speeds. Shifts faster, RESPONDs fast.

[Paunocu]

Somehow I think the difference between 100 miliseconds and 8 miliseconds is not going to make a difference, even if you guys were actually racing professionally, which I seriously doubt anybody here is because professional racers know this issue is not important.

People who don't own these cars do.

[GotBHP?]

Somehow I think the difference between 100 miliseconds and 8 miliseconds is not going to make a difference, even if you guys were actually racing professionally, which I seriously doubt anybody here is because professional racers know this issue is not important.

People who don't own these cars do.

Clearly you haven't driven on a race track or down a 1/4 mile, or maybe even done the simple math. Say on a given lap you shift 15 times. The 8 millisecond shifting car will be 1.38 seconds a lap faster with everything else being equal. That adds up to minutes over a given race. Find me one race driver that wouldn't take that kind of advantage basically for free.

[impulsoren]

The M3's clutch disengagement to clutch engagement is 8 milliseconds. Thats .008 seconds. There really is no comparison between that and any torque converter transmission out there in terms of shift times.

If the torque converter is locked, the shifting of the automatic could actually be faster at times. The clutch packs inside the auto are basically the same design as the clutch packs outside the DCT. So clutch engagement/disengagement should be the same. At times the DCT has to wait until the correct gears are selected on the gearshaft, while the auto never has to because the planetary gearsets always have all the gears meshed, the ratio just depends on which clutch pack is activated.

[GotBHP?]

If the torque converter is locked, the shifting of the automatic could actually be faster at times. The clutch packs inside the auto are basically the same design as the clutch packs outside the DCT. So clutch engagement/disengagement should be the same. At times the DCT has to wait until the correct gears are selected on the gearshaft, while the auto never has to because the planetary gearsets always have all the gears meshed, the ratio just depends on which clutch pack is activated.

The entire purpose of a dual clutch transmission is to eliminate gear selection time, because they are of course pre-selected.

[mryakan]

The entire purpose of a dual clutch transmission is to eliminate gear selection time, because they are of course pre-selected.

What if you want to skip a gear on a downshift!

[Kevlar]

What if you want to skip a gear on a downshift!

As long as you aren't going to a gear located on the same shaft you are on now it shouldn't be a big problem. If you are going to a gear on the same shaft it just jumps back to a regular clutch like action. Clutch out, gear change, clutch in.

http://auto.howstuffworks.com/dual-c...ansmission.htm

Not having driven the car... I'm willing to bet though that by the time you hit the paddle the second time to downshift and to the second gear, it will have already engaged the first.

[GotBHP?]

What if you want to skip a gear on a downshift!

Hit the paddle twice? Time is saved on upshifts, downshifts are done during braking in any sort of performance driving anyways.

[FinalBoss]

Clearly you haven't driven on a race track or down a 1/4 mile, or maybe even done the simple math. Say on a given lap you shift 15 times. The 8 millisecond shifting car will be 1.38 seconds a lap faster with everything else being equal. That adds up to minutes over a given race. Find me one race driver that wouldn't take that kind of advantage basically for free.

While the shifting time of a DCT is an advantage on the track it is not 1.38 seconds per lap. The DCT will only allow 1.38 seconds of acceleration over a traditional manual when looking at data logs.

[GotBHP?]

While the shifting time of a DCT is an advantage on the track it is not 1.38 seconds per lap. The DCT will only allow 1.38 seconds of acceleration over a traditional manual when looking at data logs.

The 1.38 seconds is the difference between a car that shifts in .1 seconds and .008 seconds in 15 shifts. All else being equal (gearing, power, aero etc.), the DCT will spend 1.38 seconds a lap accelerating while the other car is decelerating between shifts, and will be 1.38 seconds faster per 15 shifts.

That is purely the math, so if you have real world data that says differently then surely you know it could be due to 10 trillion variables out of your control. If you want to get into the physics of gearing and the power/torque production of the engine and integrate them for a theoretical laptime using accelerations, by all means write the code for a sim, and maybe I can check it against the one written for our FSAE team.

[Pyrojim1]

The 1.38 seconds is the difference between a car that shifts in .1 seconds and .008 seconds in 15 shifts. All else being equal (gearing, power, aero etc.), the DCT will spend 1.38 seconds a lap accelerating while the other car is decelerating between shifts, and will be 1.38 seconds faster per 15 shifts.

That is purely the math, so if you have real world data that says differently then surely you know it could be due to 10 trillion variables out of your control. If you want to get into the physics of gearing and the power/torque production of the engine and integrate them for a theoretical laptime using accelerations, by all means write the code for a sim, and maybe I can check it against the one written for our FSAE team.

I would actually LOVE to see that written out...I think cars are one of the few works of art that so beautifully iterate incredible complex computations into form and function(my major is pure math not applied...go figure i do not have a deep grasp on physical concepts)

[E92M3coupe]

can you explain what's the difference between "shifting fast" and "response"?

i mean, how can a car shifts fast but responds slow? jsut curious. thank you

Jamdun17 is right

the shifting time is fast, when u put it in "D". like the time between when "it" starts to shift from 1st to 2nd gear.
But when u put it in manual mode, it does not respond fast as u want it to be. like when u press the paddles upshit or downshit, it takes about 2.0-3.0sec to respond or to "think", (not 0.2-0.3sec, but 2.0-3.0sec).

But in SMGIII, MDCT, or F1 tranny, these, are REALLY talking about millionseconds, when u press the paddle.
two complete different levels of transmissions