M-DCT "preview" (by way of Mitsubishi)

[swamp2]

We can get some very valuable insight into what may likely lie in store for us with BMWs M-DCT dual clutch automated manual transmission by examining the new Evo X TC-SST (Twin Clutch-Sportronic Shift Transmission). Wow what a name, have to say I prefer simply "dual clutch transmission".

This is an optional transmission which is offered in addition to the standard 5 speed MT. It provides both automatic modes as well as a paddle shifted manual mode (almost for sure shiftable via the stick on the transmission tunnel as well - any Evo fans want to confirm that?). It's three automatic modes are Normal, Sport and S-Sport. Normal is for everyday cruising, Sport is meant for more spirited driving wheras S-Sport is for full on track use. According to Road&Track, S-Sport is far more aggressive than the sportiest VW/Audi DSG setting (again like I have been saying all along - software will be as important as the mechanical design for M-DCT as this is the only difference between the various automatic modes - software). In S-Sport mode, again a fully automatic mode, upshifts only occur at redline and downshifts occur automatically on slowing for corners. Also, according to R&T, the TC-SST system, "worked flawlessley in both manual and automatic modes" around the 2 mile Mitsubishi test track. In fact the R&T driver said that on this track the TC-SST shifted exactly where he would have if he was shifting a MT. The transmission was simply "fantastic". The only noted problem on this pre-production unit was trouble getting ideal launches (echos of BMWs SMG...). The Evo Chief Engineer insisted that this small remaining detail would be fully addressed before the production models with this transmission are released.

Last but not least, despite the new Evo X feeling slower and less edgy than the outgoing Evo IX model (it is in fact a tad slower than the outgoing IX 0-60), with TC-SST in S-Sport mode the Evo X bests the IX around this same 2 mile track by about 1 second! Some of this gain should also be attributed to the AYC (active yaw control system) which is basically an actively controlled rear differential to reduce both under and over steer. However the extra 300 lb of the X over the IX and worse power to weight ratio (11.3 lb/hp for the X vs 10.7 for the IX) is not in favor of the X achieving a better time either, so indeed AYC and TC-SST are really doing something here! Just FYI: 1 second in 2 miles would translate to about 6 seconds on the Nurburgring if the average speeds and gains scale solely on the distance of the track. Hmmm what were my personal estimates of the gains that M-DCT will show on the Ring...

Can you hear some of the same things we know about the E92 M3 vs. the outgoing M3 in this information (less edgy but a better performer)? I am confident that BMW will match or exceed Mitsubishi's excellent TC-SST with their M-DCT. If only it will get to the US simultaneously with the cars launch. Us M-DCT fans can only hope...and pray.

[Sedan_Clan]

I read about this in the new Motor Trend. Pretty sophisticated stuff........

...but I'll stick w/ my traditional manual still.

[mkoesel]

Thanks swamp. I'll probably go google this now, but I wonder - what about the manual modes?

[Epacy]

Originally Posted by Sedan_Clan

I read about this in the new Motor Trend. Pretty sophisticated stuff........

...but I'll stick w/ my traditional manual still.

Ditto. Thought of posting this here, but really only Swamp would gush over it.

[ILC32]

I definitely will not get the car untill DSG or SMG is available. I have no issues with SMG in my E46 M3, so even if DSG cannot be implemented in the M3 for whatever reason (perhaps too much hp or tq for current technology?), I would still be very happy with SMG.

[Epacy]

Originally Posted by ILC32

... even if DSG cannot be implemented in the M3 for whatever reason (perhaps too much hp or tq for current technology...

I doubt this will be a problem.

[03SG///M3]

Originally Posted by ILC32

I definitely will not get the car untill DSG or SMG is available. I have no issues with SMG in my E46 M3, so even if DSG cannot be implemented in the M3 for whatever reason (perhaps too much hp or tq for current technology?), I would still be very happy with SMG.

I second that... I would be more than fine with an SMG transmission in the E92 M3.

[GregW / Oregon]

Originally Posted by ILC32

...so even if DSG cannot be implemented in the M3 for whatever reason (perhaps too much hp or tq for current technology?), I would still be very happy with SMG.

The Getrag unit rumored for the M3 has more than enough capacity. Check out the specs...



KEY BENEFITS

- Optimized efficiency
- Shifting without interruption of traction
- Excellent comfort
- Very quick and sportive shiftings possible

KEY FEATURES
-Max. Torque Capacity 600 Nm
-Weight (dry) 79 kg
-Installation length 660 mm
-Synchronization:
1st, 2nd and 3th gear dual cone
4th and 5th gear single cone
6th, and 7th gear dual cone
Reverse gear single cone

- Gear Spread Ratio 6,8
- Max. Gross Vehicle Mass/Gross Trailer Mass 2500 kg/4500 kg
- Shifter System hydraulic

http://www.getrag.de/455

[GregW / Oregon]

I think what is really needed is a TCT (Triple Clutch Transmission) so that one higher and one lower gear can always be preselected!

[TTBear]

This is what I don't understand about the DSG transmissions. Say you are on track, acclerating in third gear, and the tranny has preselected fourth. Instead of continuing to accelerate, you approach a corner, and thus want to DOWNSHIFT into second. Won't the shift be really slow, as it has to disengage fourth, and then engage second?

Or am I missing something here?

[GregW / Oregon]

Originally Posted by TTBear

This is what I don't understand about the DSG transmissions. Say you are on track, acclerating in third gear, and the tranny has preselected fourth. Instead of continuing to accelerate, you approach a corner, and thus want to DOWNSHIFT into second. Won't the shift be really slow, as it has to disengage fourth, and then engage second?

Or am I missing something here?

It will be slower, the reason for my post above.

[mkoesel]

Originally Posted by GregW / Oregon

I think what is really needed is a TCT (Triple Clutch Transmission) so that one higher and one lower gear can always be preselected!

Actually the ideal would be one clutch per gear, so that it doesn't have to shift sequentially.

Of course, that would weigh a ton.

[aerisolphaln]

Originally Posted by TTBear

This is what I don't understand about the DSG transmissions. Say you are on track, acclerating in third gear, and the tranny has preselected fourth. Instead of continuing to accelerate, you approach a corner, and thus want to DOWNSHIFT into second. Won't the shift be really slow, as it has to disengage fourth, and then engage second?

Or am I missing something here?

I would imagine the software would overcome this issue. So you're on the track in "ultra-sport" transmission mode in 3rd gear. I would bet that 2nd gear would be pre-selected by the transmission up until you reach RPM levels in 3rd gear that would no longer be compatible with a down shift into 2nd, at which point the pre-selected gear would become 4. This would happen at the RPM point in 3rd where the down shift to 2nd would be, say, within 500 of redline, making the downshift impractical. This would make the most sense to me.

[aerisolphaln]

And I think that the slowest DCT shifts will be an order of magnitude quicker than the fastest professional human shifts.

[Sedan_Clan]

I like simplicity. This transmission, be it installed in an EVO or the M3, is just another expensive part prone to problems (..and expensive repairs after warranty).

[03SG///M3]

The aforementioned concerns stated above about the preselected gears when on the track is why i think i would prefer SMG 3.

[swamp2]

Good discussion. Hold on for a long multi-part reply...

Originally Posted by mkoesel

Thanks swamp. I'll probably go google this now, but I wonder - what about the manual modes?

Manual modes should be fairly simple. It only shifts when you click the paddles, period. I think it is likely that there will only be one manual mode. Since shifts always combine smoothness and lightning fast speeds why offer a range between slow/comfortable and fast/harsh?

Originally Posted by Celsius

Actually, I think Nissan's Dual Clutch system in the GTR might be better, but I don't think the published shift times reflect it?

There are no published shift times for BMWs nor Nissans systems AFAIK. Also we have most sources claiming 8 ms for DSG and one very credible source claiming 20-30 ms.

Originally Posted by aerisolphaln

I would imagine the software would overcome this issue. So you're on the track in "ultra-sport" transmission mode in 3rd gear. I would bet that 2nd gear would be pre-selected by the transmission up until you reach RPM levels in 3rd gear that would no longer be compatible with a down shift into 2nd, at which point the pre-selected gear would become 4. This would happen at the RPM point in 3rd where the down shift to 2nd would be, say, within 500 of redline, making the downshift impractical. This would make the most sense to me.

That is quite clever and probable I'd say. Again with software, the sky is the limit, it is only about how good they can quantify what a drive wants to happpen when.

Originally Posted by Sedan_Clan

I like simplicity. This transmission, be it installed in an EVO or the M3, is just another expensive part prone to problems (..and expensive repairs after warranty).

Don't be a luddite. There are a few good reasons to not want an M-DCT but this doesn't cut it for me. Would you say that BMWs dual VANOS system or the engine control unit with multiple 32 bit CPUs capable of 200 million calculations per second are "too complex" or subject to too many expensive repairs after warranty? There are essential components of a modern performance car that are reliable for a large percentage of the lifetime of the car (if not its entire lifetime).

Originally Posted by TTBear

This is what I don't understand about the DSG transmissions. Say you are on track, acclerating in third gear, and the tranny has preselected fourth. Instead of continuing to accelerate, you approach a corner, and thus want to DOWNSHIFT into second. Won't the shift be really slow, as it has to disengage fourth, and then engage second?

Or am I missing something here?

2 gear downshifts will make things slower but they should only get as slow as still better than any human and about like a regular SMG system. Furthermore the system will be designed for ultimate performance on the twisties and track as opposed to freeway speed contests. When decelerating on a track you typically downshift a gear at a time - just click off the paddles until you have the gear you like. The tranny knows you are decelerating and will corrrectly preselect a lower gear rather than a higher gear. Each shift can be as fast as the best upshift here. If you want two instant downshifts from say 6-4 on the freeway, for a bit of a race, you may be able to confuse the system a bit. However, even in the worst case scenario the actual clutch movements and shift mechanism movements will still be lightning fast it is just a matter of the software orchestrating the shifts you request. So for the 6-4 when in 6 the system may have 7 preselected it will then have to select 5 instead before clutch operations. Once in 5 there is the question again as to what next gear will be preselected - back to 6 or down to 4. Once that is sorted by the computer the next shift will occur. If the system realized you also gave the car full throttle I can see it getting the preselects correctly (down instead of up) as long as there is no risk of over reving, which will be contoinuosly monitored.

[Hans Delbruck]

Did Sam Mitani do the test and write the article? If so, then he's a good driver, and I believe it.

Otherwise, the new Evo SST trans takes a car that is already way too easy to drive fast, and makes it even easier. No wonder it's easy for an intermediate-novice-weekend track guy to go faster in the auto mode.

What this means in my NSHO (not so humble opinion) ... we are going to see more Evo drivers getting in over their heads and driving above their skills on the track and the street with this car. This car makes anyone look like a hero. The new one is going to take "point and steer" to a new level of 'no skills required.' I have personally witnessed how dangerous this car can be in the hands of a novice.... when things go wrong, it gets ugly really quick. These cars are prone to dig in and roll. Especially when the noobie drivers think it's ok to test their off-road capability at a track day.

Evo rant off (for now!)

[mkoesel]

Originally Posted by swamp2

Manual modes should be fairly simple. It only shifts when you click the paddles, period. I think it is likely that there will only be one manual mode. Since shifts always combine smoothness and lightning fast speeds why offer a range between slow/comfortable and fast/harsh?

Well I don't know the answer to the last question, but from what I found when I googled there are three manual modes, just like there are three auto modes. However, I could not find a detailed explanation of the differences between them.

[Sedan_Clan]

Originally Posted by swamp2

Don't be a luddite. There are a few good reasons to not want an M-DCT but this doesn't cut it for me. Would you say that BMWs dual VANOS system or the engine control unit with multiple 32 bit CPUs capable of 200 million calculations per second are "too complex" or subject to to many expensive repairs after warranty? There are essential components of a modern car that are reliable for a large percentage of the lifetime of the car (if not its entire lifetime).

Sure it is, but as I implied previously, this is one less thing to have to worry about. Plus, I love my clutch pedal!

[swamp2]

Originally Posted by Hans Delbruck

Did Sam Mitani do the test and write the article? If so, then he's a good driver, and I believe it.

Otherwise, the new Evo SST trans takes a car that is already way too easy to drive fast, and makes it even easier. No wonder it's easy for an intermediate-novice-weekend track guy to go faster in the auto mode.

It was Sam Mitani.

There is nothing wrong IMO with making high performance driving easier and I think the Evo X and E92 M3 will both excel in this area. I agree with your comments about getting in over your head but hey with systems as thorough and good as DSC I say, "why not".

[swamp2]

Originally Posted by mkoesel

Well I don't know the answer to the last question, but from what I found when I googled there are three manual modes, just like there are three auto modes. However, I could not find a detailed explanation of the differences between them.

Sounds reasonable. I suppose you can still tweak the continuum between comfort and sport even in manual mode. If the Evo offers multiple manual modes I'd strongly bet the M3 will as well. Do share the difference between manual modes if you can figure it out. I am very interested.