[BMWCOUPE]

Can someone explain to me the advantages of a DCT in the 335is over the standard transmission in the 335i?

What exactly does it do?

[Dozhdbog]

Shifts faster than pretty much anyone on the planet can in a manual.

[Dozhdbog]

Nearly perfect rev-matching downshifts.

[Dozhdbog]

I think that's about it.

[Saintor]

Less slippage while accelerating. Almost nonexistent gear shift change.

Probably more expensive just to maintain; S-Tronic or DSG (VW/Audi) require 350-400$ 40000 miles maintenance).

Yet the new ZF 8-sp. makes it less appealing.

[SilverII]

launch control

[BMWCOUPE]

Originally Posted by Dozhdbog

Shifts faster than pretty much anyone on the planet can in a manual.

So in layman's terms it's faster than a standard transmission? If so by how much?

For example if there was a 335i with dct and one without how much faster would the one with DCT be?

[Saintor]

Originally Posted by BMWCOUPE

So in layman's terms it's faster than a standard transmission? If so by how much?

For example if there was a 335i with dct and one without how much faster would the one with DCT be?

Depending on the source, regular ZF shift in 100-200ms. A blink of eye is 300ms. Best DCT I heard (under reserve) of is 40-60ms. Don't know abut BMW's DCT.

[mike-y]

Also, pretty much impossible to mis-shift a DCT.

[BMWCOUPE]

Originally Posted by Saintor

Less slippage while accelerating. Almost nonexistent gear shift change.

Probably more expensive just to maintain; S-Tronic or DSG (VW/Audi) require 350-400$ 40000 miles maintenance).

Yet the new ZF 8-sp. makes it less appealing.

Interesting, thanks

[Saintor]

Originally Posted by 335isWhite

Go to youtube and search for Dual Clutch Transmission animation.

You will find great videos! if I am not mistaking it was first invented by porsche and basically you have two clutch for each set of gears which helps to minimize the interval between shifs. porsche calls it PDK, and VW calls it DSG.
Audi did a great job on their new TT-RS (europian version has DCT).
Here are some fantastic numbers by Audi TT-RS:
- Manual transmission: 0-60 in 4.6sec (available in US market)
- DCT: 0-60 in 3.6sec!!! (not available in the US)

I think that it is also related to 'Launch Control' program, not present on manual IIRC.

[BMWCOUPE]

Originally Posted by 335isWhite

Go to youtube and search for Dual Clutch Transmission animation.

You will find great videos! if I am not mistaking it was first invented by porsche and basically you have two clutch for each set of gears which helps to minimize the interval between shifs. porsche calls it PDK, and VW calls it DSG.
Audi did a great job on their new TT-RS (europian version has DCT).
Here are some fantastic numbers by Audi TT-RS:
- Manual transmission: 0-60 in 4.6sec (available in US market)
- DCT: 0-60 in 3.6sec!!! (not available in the US)

Thanks for the detailed explanation. Wow big difference in the 0 to 60 times. Yet another reason to upgrade my 08 335i to a brand new 335is.

[Kolyan2k]

I remember some magazine did comparison on E46 6-speed M3 vs SMG M3 and out of 10 launches by pro driver only 1 matched SMG, other 9 launches were slower and not consistent. SMG all 10 launches gave pretty much the same time.

[gary88]

Originally Posted by Saintor

Less slippage while accelerating. Almost nonexistent gear shift change.

Probably more expensive just to maintain; S-Tronic or DSG (VW/Audi) require 350-400$ 40000 miles maintenance).

Yet the new ZF 8-sp. makes it less appealing.

I drove a new 650i with the ZF 8 speed last year, pretty much equals DCT in shift times.

[dryicerx]

• Lightning quick shifts
• Ability to provide uninterrupted torque during gear shifts. This also means also to some degree keeping boost during gear shifts as well.
• Launch control feature
• Rev matched shifts
• Lack of a torque converter (for all intents and purposes, a DCT is two manual transmissions with it's own clutch, one with all the odd gears and the other with all the even gears).

Originally Posted by BMWCOUPE

Thanks for the detailed explanation. Wow big difference in the 0 to 60 times. Yet another reason to upgrade my 08 335i to a brand new 335is.

Bear in mind that in a most cars, 335is included, you won't see that big of a improvement of 0-60 times between Manual and DCT (I'm guessing on the TT-RS launch control is magical, or other factors such as US vs Euro spec).

[rgbimmer]

if you got in a drag race with the identical car only manual trans, you would smoke it unless it was a very experience driver.

[BEAR-AvHistory]

Its got real clutches & real gears...think of it as a 7MT driven by a robot. One reason its quick is not just the pure shift time but the fact that you don't need to lift the throttle between shifts so you are never out of the power.

When running against a MT you can see the drop back on every shift when they lift. If they don't lift on the shifts you might see the car grenade as it will happen sooner or later with out a properly prepared gear box that is not suitable for the street.

[BQTuning]

The 335is DCT should not even be compared to a regular automatic transmission of the 335i. They have absolutely no relation to one another.

DCT is more in relation to Manual Transmission but it is automated and has two clutches

[Dozhdbog]

How are the shifts, Bear, are they smooth during normal driving as well as under throttle?

[a7med606]

i heard that the 7speed is converting more horsepower to the wheel than the 6auto

for example comparing a stock dyno runs between the two cars
both of them has n54 with 306 engine horsepower
the 7 speed dct will give you 250 whp
the 6 auto will give you 240 or 230

these are not real dyno numbers but i am trying to explain that the dct will give you more power in the wheel than the 6 speed auto

[Dozhdbog]

I wish I understood the mechanics better. The a/t outputs more torque than the manual when the PPK is installed to a 335.

[Taipei-TT]

Has anyone driven the ZF 8speed against any dual clutch back to back?

For me, more so than just shift speed, what I loved about my old S-tronic was the lack of 'slushy' feeling by not having a torque converter. Does the ZF solve this problem too? I have the 6 speed GM box in my 325...while I can't say it's terrible, I can say it is the worst part of my car! I would have got MT, but that is not possible in the Taiwan market. Some days it just makes me go....grrrrr! It shifts reasonably quickly most of the time, but does not have the immediacy that the direct connection of a MT and dual-clutch box offers. So that's what I really want to know...how does the ZF 8 speed feel, not just how quickly it shifts.