First driving reviews of M3 M-DCT / M-DKG transmission!

[ersin]

Originally Posted by DonM3

FYI Theres a whole gearbox feature in the March edition of Evo car mag. Might be relevant to this discussion.

Sorry no scans.

I'd love to see that. Unfortunately, we're a month or so behind in getting Evo here in the states. But, I'll be looking for it.

[DonM3]

Its very good. Someone will surely post scans before too long

[rai]

questions about DCT?

I don't want to start a new thread, hopefully somebody can chime in. the thread is hard to follow but I think people prefer one thread at a time about the DCT.

My questions..

I have driven one car with a DCT which was the GTi (called DSG)

When I test drove the car, I didn't know fully how to do everything with the tranny and this was about 2 years ago so going back my memory may be wrong.

Here is what I remember. When the car was in Auto mode it was shifting itself as you would expect. But at anytime while it was in Auto mode, I could change the gear with the paddles if I wanted for some reason and the car would turn into the Manual mode for a while (I think would go back to Auto mode after a while). Does the M3 allow this? (I mean can you over-ride the auto mode with the paddle shifters?)

Another thing I recall was when in Manual mode it would still shift-up at the redline. Some people don't like this but I think it could have it's place. If you forget you are in Manual mode, you may not want to be banging on the redline not going anywhere.

Is there a very aggressive Auto mode like you see in the M6 video where basically you can stand on the gas and the car will do everything shift at redline which should be just as quick as the quickest Manual mode (I would think).

How does BMW do with the SMGs in M5/6 etc. I mean besides many people saying the auto mode is not smooth, but as a performance tool do people think it's a lot better than a 6MT?

Thanks if anyone would care to inform me.

[ersin]

Originally Posted by rai

questions about DCT?

I don't want to start a new thread, hopefully somebody can chime in. the thread is hard to follow but I think people prefer one thread at a time about the DCT.

My questions..

I have driven one car with a DCT which was the GTi (called DSG)

When I test drove the car, I didn't know fully how to do everything with the tranny and this was about 2 years ago so going back my memory may be wrong.

Here is what I remember. When the car was in Auto mode it was shifting itself as you would expect. But at anytime while it was in Auto mode, I could change the gear with the paddles if I wanted for some reason and the car would turn into the Manual mode for a while (I think would go back to Auto mode after a while)

Another thing I recall was when in Manual mode it would still shift-up at the redline. Some people don't like this but I think it could have it's place. If you forget you are in Manual mode, you may not want to be banging on the redline not going anywhere.

Is there a very aggressive Auto mode like you see in the M6 video where basically you can stand on the gas and the car will do everything shift at redline which should be just as quick as the quickest Manual mode (I would think).

How does BMW do with the SMGs in M5/6 etc. I mean besides many people saying the auto mode is not smooth, but as a performance tool do people think it's better than a 6MT?

Thanks if anyone would care to inform me.

SMG is slightly different in it's operation from what you have described for the DSG.

1. If you are in auto mode and pull a paddle, it will instantly shift (if it won't over-rev the engine) and go into manual mode. To return to auto you have to switch it back manually by bumping the shifter to the right.

2. In manual mode it will not upshift at redline for you. If you don't shift yourself then you will bounce off of the rev limiter.

3. I believe in that video the M6 is in manual (they call it sequential) mode. I don't know if the M6 will chirp it's wheels during shifting in auto mode.

4. Performance-wise, some will tell you the SMG is better, others say no. Different people have different experiences and ideas. Some find that the SMG transmission is not engaging enough to be sporty.

The M-DCT sounds like it will be similar in operation to SMG. However, it is a very different transmission and this similarity only applies to the user interface. We expect M-DCT to be an improvement to SMG all around -- smoother, faster, more efficient. Can't wait for the first reviews.

[rai]

Originally Posted by ersin

SMG is slightly different in it's operation from what you have described for the DSG.

thanks, I got a chance to drive both the F430 (with F1 tranny) and Lambo Gallardo (with e-gear tranny).

This was a paid driving event just on public roads. But I only got like 15 minutes each and just left in Manual mode. I did not get enough time to absorb what was happening. I mean I pulled the paddles and up or down-shift. Of course I had a blast, I do not know if or if not the 6MT would have been any more fun. It's hard for me to decide.

I hope to make my decision. I know some people are in one camp or the other. But I am just in the middle and I need to make my decision soon before my order gets to the point I can't change it.

Thanks if anyone else cal help me make a good decision.

I will say, I have a S2000 and will be keeping it and if any have driven that has perhapse the best 6MT in production. I would say if the S2000 is a 10 (of 10) on my test drive of the M3 the was a 7 or 8. I didn't hate it but it was not up to the best I've ever driven. I could really live with the 6MT but with all this talk about how good the DCT is and having liked other cars with DSG or SMGs I am maybe leaning to that. My problem is all my DSG/SMG driving put together is less than an hour so I really don't know the warts just that I liked it for the short time I had.

[ersin]

FWIW, I've been driving manual transmissions for ... let's just say since I got my license. I had a 2002 M3 with SMG. I like both transmissions. Each has good and bad points. Both were engaging and fun. If M-DCT is all that they say it is then I will probably get that when the time comes.

[T Bone]

Originally Posted by swamp2

Come on T, stop with the annoying misrepresentations. I have explained my DISBELIEF in BMWs statement of shifts in "milliseconds" time and time again. I used such numbers occasionally in simulations but not generally. Your lie and pesky nature on this is getting soooo old. Don't forget you tried to sucker bet me with known detailed knowledge on SMG III shift times and how that would compare to DCT.

I should have taken you up on the bet when you keep getting confused between seconds and milliseconds, DCT shifts faster than 0.8 s?

I'm getting dangerously close about the 80 ms number, but not yet. I put 100 ms on the table.

What happened to your massive flip flop right here in this thread on the decelerative spike on the leading edge of the shift? My 2nd proposed bet?

COme on, if we were all perfect, we would be Footie

Alright we will never come to an agreement over terms....

[T Bone]

Originally Posted by footie

T-Bone,

When enigma provides a graph on the SMG then I will give you a wager based on what I believe the DCT will look like in comparison and how long the period will be.

If swamp won't, I will.

Sure what do you want to bet on? Name the parameters. Seems to only way to shut you up is humilation.

Originally Posted by footie

Can I get a little off topic and it's my opinion why SMG was a badly executed design.

Would everyone admit here that in anything other than S6 mode the M6 will be beaten by quite a few cars which wouldn't stand a chance when in S6 mode. Surely that is a major failings in it's design when only the roughest of settings give the desired results.

Also with the new DCT, only S6 disconnects DSC (not sure of this being right) and in this mode the car has the most surge which will unbalance the chassis in corners when shifting.

Feel free to knock my opinions down but I don't agree with what BMW is doing and has done with their semi-automatics.

Besides your technical inaccuracies, what idiot shifts mid corner under high lateral g loads? In any type of tranny?

Originally Posted by Wads

If anyone is interested I have similar acceleration trace data to that posted by Enigma..... I have data for the E92 M3 Manual, Golf R32 DSG and M5 SMG (all Euro spec driven by the same driver (me) on the same stretch of road).

I use the Racelogic Performance box with is twice as accurate as the DL1 (10 samples a second Vs 5)

Yes please!!! What resolution can you offer?

[Wads]

Here are the traces for the Golf R32 DSG, M3 Manual and M5 SMG (pictures in that order)

The Golf changes are so smooth that there are no obvious flat spots in the curve...... this was in the manual shift sport mode.

The M3 shift flat spot between 1st and 2nd gears takes 0.48 seconds.

The M5 (in S6 mode) shift from 1st to 2nd takes 0.26 seconds.....

These were the best 1st to 2nd gear examples I have for the M3 and M5...... I should add that I've driven sports manuals for 22 years and the M-DCT is the first "auto" I've considered..... by considered I mean I'll almost certainly be confirming my order on Monday

[ersin]

Thanks Wads. It's a real eye opener. That DSG is a real smooth operator.

[bruce.augenstein@comcast.]

Originally Posted by T Bone

Besides your technical inaccuracies, what idiot shifts mid corner under high lateral g loads? In any type of tranny?

Uh, this idiot?

I'm not completely sure of it, but it appears that footie is playing at a much higher level than you are in this discussion.

Anybody shifts in a corner if that's where the car dictates a shift. It's awfully damned simple. As a for instance, in the Carousel at Mont Tremblant, many, many cars have to pick between second and third gear going in. Those that need second are going to have to shift somewhere in the corner, and no matter. You've just got to manage the shift so as not to end up playing the clown.

My old Neon absolutely had to have second gear going through there, else I'd lose between seven and eight mph at the end of the following straight - the longest straight on the course. Coming out of Namerow at the same track, practically everybody with fairly short gearing has to shift while stilll pulling at or close to max G. It's the nature of the beast.

Shifting during a corner is routine. You absolutely don't do it unless you have to, but sometimes you must.

Anybody with serious track time would understand this.

Bruce

[ersin]

Hey, you know what? Even during shifting the acceleration does not drop below zero for any of those trannys.

[Wads]

Originally Posted by ersin

Hey, you know what? Even during shifting the acceleration does not drop below zero for any of those trannys.

I assume thats down to momentum?

[ersin]

Originally Posted by Wads

I assume thats down to momentum?

No, momentum just keeps the speed constant. Because of losses -- friction and drag -- acceleration should be negative. I would chalk it up to resolution of the accelerometer because I cannot think of why the SMG wouldn't be negative.

[impulsoren]

I'm coming into this pissing contest a little late it seems, but any car with a decent amount of weight tied up in the drivetrain behind the clutch (mostly wheels and tires) is going to not decelerate when the clutch is pushed in. Particularly if you use NLTS programming in whatever car/tranny system you are using thus no engine braking prior to clutch disengagement. I thought it would be closer to zero, but not negative?

[T Bone]

Originally Posted by bruce.augenstein@comcast.

Uh, this idiot?

I'm not completely sure of it, but it appears that footie is playing at a much higher level than you are in this discussion.

Anybody shifts in a corner if that's where the car dictates a shift. It's awfully damned simple. As a for instance, in the Carousel at Mont Tremblant, many, many cars have to pick between second and third gear going in. Those that need second are going to have to shift somewhere in the corner, and no matter. You've just got to manage the shift so as not to end up playing the clown.

My old Neon absolutely had to have second gear going through there, else I'd lose between seven and eight mph at the end of the following straight - the longest straight on the course. Coming out of Namerow at the same track, practically everybody with fairly short gearing has to shift while stilll pulling at or close to max G. It's the nature of the beast.

Shifting during a corner is routine. You absolutely don't do it unless you have to, but sometimes you must.

Anybody with serious track time would understand this.

Bruce

Footie at a high level??


Yes, I understand what you are saying and I have not driven Mount Tremblant.....so equating this to tracks that I know.....

• I would never shift at Mosports's 2nd and 4th corners
• I would not shift through the essess at Watkins Glen
• I would shift mid-way through the corner just before Fabi Straight at Shannoville

[Wads]

Originally Posted by ersin

No, momentum just keeps the speed constant. Because of losses -- friction and drag -- acceleration should be negative. I would chalk it up to resolution of the accelerometer because I cannot think of why the SMG wouldn't be negative.

I can't claim to be an expert on the physics side of things but if the speed continues to increase during the gear change surely that is still considered as positive acceleration? When the speed starts to decrease the acceleration trace dips below zero..... at least thats how the various tests I've done seem to work.

[ersin]

Originally Posted by Wads

I can't claim to be an expert on the physics side of things but if the speed continues to increase during the gear change surely that is still considered as positive acceleration? When the speed starts to decrease the acceleration trace dips below zero..... at least thats how the various tests I've done seem to work.

Yes, that's correct. But momentum opposes acceleration. So if the car is still accelerating during the shift it is not because of momentum. You see, momentum, both the forward and the rotational (angular) kind, will keep the car going but won't make it go any faster. If the car is still accelerating then it is getting faster. So it is not because of momentum.

If the car is still accelerating then there must be some force making it gain speed. Newton said F = ma, that is, acceleration is proportional to force. If there is acceleration there must be a force involved (although it may be "fictional" but let's ignore that).

[enigma]

Originally Posted by ersin

No, momentum just keeps the speed constant. Because of losses -- friction and drag -- acceleration should be negative. I would chalk it up to resolution of the accelerometer because I cannot think of why the SMG wouldn't be negative.

The graphs look as if there is some smoothing of acceleration data occuring. Same in mine. I have the DL1 in the SMG car today. I'll see how close mine line up when I get home.

[ersin]

Originally Posted by enigma

The graphs look as if there is some smoothing of acceleration data occuring. Same in mine. I have the DL1 in the SMG car today. I'll see how close mine line up when I get home.

Yes, that's probably it. It is a digital instrument, that is to say it gives you digital information. The internal software probably applies a smoothing algorithm before outputting it to the computer.

[enigma]

Originally Posted by bruce.augenstein@comcast.

Uh, this idiot?

I'm not completely sure of it, but it appears that footie is playing at a much higher level than you are in this discussion.

Anybody shifts in a corner if that's where the car dictates a shift. It's awfully damned simple. As a for instance, in the Carousel at Mont Tremblant, many, many cars have to pick between second and third gear going in. Those that need second are going to have to shift somewhere in the corner, and no matter. You've just got to manage the shift so as not to end up playing the clown.

You are both right, but Bruce more so. You shift when you have to (and can). There are some turns where the car makes it impossible.

For example T14 at thunderhill. I would really, really like to go down to 2nd on entry. However, if I do this it means shifting back 2->3 on the way out. That requires lifting to shift which would mean the elise spins right off the track. In that case its faster to drive around at the limit in 3rd rather than far enough from the limit in 2nd to allow the shift.

On the other hand in the M3 at GIR I would shift 3->4 in the bowl with no problems. Depends on the turn and car.

By not unloading the rear tires DCT should allow you to shift in places you couldn't with the manual.

[T Bone]

Originally Posted by Wads

Here are the traces for the Golf R32 DSG, M3 Manual and M5 SMG (pictures in that order)

The Golf changes are so smooth that there are no obvious flat spots in the curve...... this was in the manual shift sport mode.

The M3 shift flat spot between 1st and 2nd gears takes 0.48 seconds.

The M5 (in S6 mode) shift from 1st to 2nd takes 0.26 seconds.....

These were the best 1st to 2nd gear examples I have for the M3 and M5...... I should add that I've driven sports manuals for 22 years and the M-DCT is the first "auto" I've considered..... by considered I mean I'll almost certainly be confirming my order on Monday

Thanks for the G reads.... I took a closer look at the charts and if you look at the distance between the g force plateaus (periods of steady acceleration), it looks like the DSG is taking a long time to do the shifting (i.e. completely disengaging one clutch and then ensuring a smooth engagement of the other).

While the g-curve looks very smooth, there is a lot of time wasted in smoothing out acceleration.

I would surmise in D1-3 for MDCT, the g-curves will look like the DSG curve. For S6, it will look like the SMG curve but with a shorter time between acceleration plateaus. BTW, this would be the beauty for MDCT, the ability to be smooth in one setting and balls out aggressive in another.