Is the DCT unit the same as in the previous generation M3?

[F80Dreamer]

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Picking up my DCT F80 in a few weeks...does anyone know if this version of the DCT is different than the previous gen cars? I used to have the DCT in my 2011 M3 and thought it was pretty good. Wondering if I should expect same or even better? Thx

[YangEnterprise]

Having driven a handful of E9x M3's with the DCT gearbox and personally owning an F8x M4 equipped with the DCT gearbox, I would have to say the F8x DCT gearbox is similar if not slightly better all around than the E9x M3.

[mercedesc63]

Originally Posted by F80Dreamer

Picking up my DCT F80 in a few weeks...does anyone know if this version of the DCT is different than the previous gen cars? I used to have the DCT in my 2011 M3 and thought it was pretty good. Wondering if I should expect same or even better? Thx

My f80 m3 is much jerkier than my e93 m3.

[shahano]

different DCT. the one of the e92 is geared towards high rev/low tq, where as the f82 is the same as the f10 m5 (different final drive) which are made for high tq.

[JDE92M3]

I still own my E90 M3 and have a F80 M3. And I think the E90 M3 is a smoother DCT overall, could be due to the GTS DCT SW. The F80 out of the box definitely seems to shift harder/faster in the highest settings, compared to the E90 M3. But other than that, both DCTs are very alike.

[GrussGott]

Originally Posted by JDE92M3

I still own my E90 M3 and have a F80 M3. And I think the E90 M3 is a smoother DCT overall, could be due to the GTS DCT SW. The F80 out of the box definitely seems to shift harder/faster in the highest settings, compared to the E90 M3. But other than that, both DCTs are very alike.

This - broadly, they're the same. However comparatively I find them totally different ... the F8x is way more violent and, of course, the shift points are all different. I'm a 100% manual shifter and it took me a few weeks to get used to the F8x and much longer to get a real hang on controlling the car (assuming I can now ... it's so hard to tell ).

[dailym3]

Originally Posted by GrussGott

This - broadly, they're the same. However comparatively I find them totally different ... the F8x is way more violent and, of course, the shift points are all different. I'm a 100% manual shifter and it took me a few weeks to get used to the F8x and much longer to get a real hang on controlling the car (assuming I can now ... it's so hard to tell ).

Curious if you have a technique for driving in manual mode slowly...without the car being incredibly jerky while slowing down into 2nd and 1st gears? The only thing that seems to be somewhat smooth is if you just wait until the revs drop to the bare minimum (just before the car downshifts for you) and then drop into 2nd or 1st. Anything other than that and it really seems to somehow interfere with the braking in a very sudden way, not a typical engine braking, linear way if you get my meaning. It almost feels like the brakes are stabbed automatically. I'm not talking about high rpm downshifting either. Just normal, around town, coming up to a stop light kind of driving.

I love manual mode on the track or while driving quickly on the back roads.

[mephiska]

Originally Posted by dailym3

Curious if you have a technique for driving in manual mode slowly...without the car being incredibly jerky while slowing down into 2nd and 1st gears?

Never downshift into 1st. It's entirely unnecessary at any speed. It's only for when the car is at a dead stop, at which point the computer automatically puts it into 1st anyway.

[Don Molina]

Originally Posted by JDE92M3

I still own my E90 M3 and have a F80 M3. And I think the E90 M3 is a smoother DCT overall, could be due to the GTS DCT SW. The F80 out of the box definitely seems to shift harder/faster in the highest settings, compared to the E90 M3. But other than that, both DCTs are very alike.

I think on the hardest setting the ECU shifts and keeps full boost, so I think the jerkiness is not from smooth operation of the gearbox, but from the car's monumental torque.

[GrussGott]

Originally Posted by dailym3

Curious if you have a technique for driving in manual mode slowly....Just normal, around town, coming up to a stop light kind of driving.

Originally Posted by mephiska

Never downshift into 1st. It's entirely unnecessary at any speed. It's only for when the car is at a dead stop, at which point the computer automatically puts it into 1st anyway.

This - around town coming to a stoplight I let the car downshift and its completely transparent that it's happening, no jerkiness. As you slow down the car will basically just open the clutch, take you out of gear, and then keep moving down unless you hit the accelerator at which point it closes the clutch. So there's no need to downshift unless you want max instant power for full throttle or you want the engine braking.

Summary:

* Coming to stop light: just slow down, car will open the clutch all the way to 1st at a full stop. If you start before a full stop the car will gently close the clutch when you hit the accelerator (at least that's what it feels like - in any event, no jerkiness)

* Traffic - personally I use engine braking usually bopping between 2nd and 3rd. In those cases with my wife in the car I use S1, sport throttle and there's no jerkiness. If there was, believe me, I'd hear about it.

[CanAutM3]

Short answer: NO

As someone has already posted, the DCT in the F8X is an entirely new unit compared to the one in the E9X with completely different gear ratios. The E9X's one was designed around high revs while the F8X's one around high torque. On the F8X, 5th gear is the 1:1 ratio while 7th is on the E9X; which was a smart design characteristic from a fuel efficiency perspective. The DCT in the F8X is also shared with F1X M5/6. I find the DCT in the F8X to be smoother in operation in the "smooth setting" (S1/D1) compared to the E9X. What I dislike with the DCT in the F8X, is that was primarily designed for the M5/6 and the S63. As a result, 1st gear is uselessly short in the F8X (due to the shorter final drive).

[mkoesel]

Originally Posted by mephiska

Never downshift into 1st. It's entirely unnecessary at any speed. It's only for when the car is at a dead stop, at which point the computer automatically puts it into 1st anyway.

Sharply disagree. First gear is just another gear ratio. It is no more special than any other gear ratio in the transmission.

We know this because the DCT is programmed to automatically downshift to 1st gear (just like it would any other gear) if you are going slow enough and you execute a kick-down for max acceleration. If you think about it, this makes perfect sense - match up against another M3/M4 from a low speed roll while you are both cruising in 3rd gear and choose 2nd gear while they choose 1st. Assuming a suitably sticky surface, you'll get beaten down - and badly at that.

Now, it is definitely true that it is never outright necessary to downshift to first gear while moving. For that matter though, it is possible to drive an M3/M4 and never, ever use first gear at all. If you aren't trying to achieve maximum acceleration from a stop or from a low speed, you can just use second gear.

[GrussGott]

Originally Posted by mkoesel

Now, it is definitely true that it is never outright necessary to downshift to first gear while moving. For that matter though, it is possible to drive an M3/M4 and never, ever use first gear at all. If you aren't trying to achieve maximum acceleration from a stop or from a low speed, you can just use second gear.

This too. Purely for purposes of hooning, I use 1st on slow speed corners if I want maximum douche pirate

[mephiska]

Originally Posted by mkoesel

Sharply disagree. First gear is just another gear ratio. It is no more special than any other gear ratio in the transmission.

We know this because the DCT is programmed to automatically downshift to 1st gear (just like it would any other gear) if you are going slow enough and you execute a kick-down for max acceleration. If you think about it, this makes perfect sense - match up against another M3/M4 from a low speed roll while you are both cruising in 3rd gear and choose 2nd gear while they choose 1st. Assuming a suitably sticky surface, you'll get beaten down - and badly at that.

Now, it is definitely true that it is never outright necessary to downshift to first gear while moving. For that matter though, it is possible to drive an M3/M4 and never, ever use first gear at all. If you aren't trying to achieve maximum acceleration from a stop or from a low speed, you can just use second gear.

You're right about 1st being useful for hard acceleration (and hooliganism), I wasn't thinking about that. My answer was more in the context of how to drive the car "slowly" in manual mode as dailyM3 was asking. For casual, every day use I still say you should avoid 1st gear unless you're at a dead stop if you don't want the car to be "jerky".

[ENTER_NAME_HERE]

My e90 DCT box was clunky and slow to engage the clutch in 1st. My F82 is phenomenal.

[CaryTheLabelGuy]

Originally Posted by Don Molina

I think on the hardest setting the ECU shifts and keeps full boost, so I think the jerkiness is not from smooth operation of the gearbox, but from the car's monumental torque.

Just so you guys know:

In S2, the DME commands a decent amount of ignition retard/cut during up-shifting, which helps smooth out the shifts along with less Initial clamping force when the associated clutch closes.

For downshifts, S2 blips the throttle quickly for rev-matching, but not as fast or violent as S3

In S3, ignition timing isn't as regarded or cut between gear up-shifts, which means max torque when the associated clutch closes. Also, initial clamping force is more violent in S3 mode and because the DME isn't cutting/retarding timing between shifts, max boost/power is maintained through the actual shift from one clutch to the other. Target boost can also slightly spike during each gear change.

S1, however, is lazy on the upshifts and does not blip the throttle at all on downshifts. I find S1 to be pretty useless.

[CanAutM3]

Originally Posted by CaryTheLabelGuy

Just so you guys know:

In S2, the DME commands a decent amount of ignition retard/cut during up-shifting, which helps smooth out the shifts along with less Initial clamping force when the associated clutch closes.

For downshifts, S2 blips the throttle quickly for rev-matching, but not as fast or violent as S3

In S3, ignition timing isn't as regarded or cut between gear up-shifts, which means max torque when the associated clutch closes. Also, initial clamping force is more violent in S3 mode and because the DME isn't cutting/retarding timing between shifts, max boost/power is maintained through the actual shift from one clutch to the other. Target boost can also slightly spike during each gear change.

Thanks for sharing

Knowing you, I have to assume you got those from data logs . It confirms my driving impressions. Just to add, the fact that S3 has minimal power cut during the upshift also means maximal recuperation of the engine inertia.

Originally Posted by CaryTheLabelGuy

S1, however, is lazy on the upshifts and does not blip the throttle at all on downshifts. I find S1 to be pretty useless.

From a performance standpoint, S1 is far from being optimal. I however like it a lot for the DD and it is my default DD setting along with Efficient/Confort/Comfort. I like to select my own gears, but I like the smoothness of S1 even when accelerating hard at higher RPM (merging onto a highway for example).

At the track, it is S3 all the way

[TRZ06]

Originally Posted by CanAutM3

Thanks for sharing

Knowing you, I have to assume you got those from data logs . It confirms my driving impressions. Just to add, the fact that S3 has minimal power cut during the upshift also means maximal recuperation of the engine inertia.

From a performance standpoint, S1 is far from being optimal. I however like it a lot for the DD and it is my default DD setting along with Efficient/Confort/Comfort. I like to select my own gears, but I like the smoothness of S1 even when accelerating hard at higher RPM (merging onto a highway for example).

At the track, it is S3 all the way

Don't you find S3 to upset the chassis at all ?

[CanAutM3]

Originally Posted by TRZ06

Don't you find S3 to upset the chassis at all ?

Not at all, quite the contrary actually. That's the beauty of the DCT Drivelogic. Even in S3, when the sensors detect the car is under lateral load, the DCT will execute a butter smooth shift (similar to S1). So you can shift mid-corner with your right foot planted to the floor and the chassis wont budge. Something that is impossible to do with a MT.

[jhbodle]

Originally Posted by CanAutM3

Not at all, quite the contrary actually. That's the beauty of the DCT Drivelogic. Even in S3, when the sensors detect the car is under lateral load, the DCT will execute a butter smooth shift (similar to S1). So you can shift mid-corner with your right foot planted to the floor and the chassis wont budge. Something that is impossible to do with a MT.

When I tried that in S3 on a steep uphill curve the back end stepped out even with traction control fully on. I have used S2 ever since.

[ApexL8]

Ok threadjackers. Back to the OP.

First off, BMW does not make The transmission. Getrag makes DCT for most European cars that have DCT's.

The transmission in your new M3 is very similar to the DCT in your previous M3. There have been some improvements and some gearing changes. The way these transmissions behave (as the driver percieves it) is entirely as a result of programming the TCU.

For your reading pleasure: http://www.getrag.com/en/products/po...smissions.html