DCT on Track & Downshifting Problem

[sayemthree]

MarksM had an issue where he tried to downshift from 4-3 and it refused. human nature is to try again and he then got 2nd gear, a big over rev and suprise. thats not safe?

[hakaida442]

Originally Posted by Mickb

A lot of speculation here I'm afraid. Just in case I wasn't clear in my initial posts, the failure to downshift occurred during heavy braking and on the straights, i.e. before I had put any steering angle on the car or turned in. I always have my cornering gear selected before turning in, so this wasn't a case of the car trying to prevent a potentially troublesome downshift during a turn. If you have some inside knowledge on this then great, but I really feel the system is potentially fatally flawed if it won't allow a downshift on a straight during heavy braking.

Secondly, I had no problem upshifting during long drifts transitioning from 2nd to 3rd gear.

Finally, I find it kind of ironic that the BMW promo video that we all saw before the DCT was available made a huge amount of its ability to shift during cornering causing no loss of momentum or balance to the vehicle. If they have now engineered in this "safey" facility that would be pretty sad IMO.

I could understand it if they left this in on certain modes, but it should be possible for the driver to communicate to the vehicle that "YES I WANT FULL MANUAL CONTROL EVEN IF THIS CAUSES VEHICLE INSTABILITY".........restrict it to S6/DSC off if you will but teh current situation is unacceptable IMO.

[MarksM]

Originally Posted by Mickb

A lot of speculation here I'm afraid. Just in case I wasn't clear in my initial posts, the failure to downshift occurred during heavy braking and on the straights, i.e. before I had put any steering angle on the car or turned in. I always have my cornering gear selected before turning in, so this wasn't a case of the car trying to prevent a potentially troublesome downshift during a turn. If you have some inside knowledge on this then great, but I really feel the system is potentially fatally flawed if it won't allow a downshift on a straight during heavy braking.

Secondly, I had no problem upshifting during long drifts transitioning from 2nd to 3rd gear.

Finally, I find it kind of ironic that the BMW promo video that we all saw before the DCT was available made a huge amount of its ability to shift during cornering causing no loss of momentum or balance to the vehicle. If they have now engineered in this "safey" facility that would be pretty sad IMO.

I could understand it if they left this in on certain modes, but it should be possible for the driver to communicate to the vehicle that "YES I WANT FULL MANUAL CONTROL EVEN IF THIS CAUSES VEHICLE INSTABILITY".........restrict it to S6/DSC off if you will but teh current situation is unacceptable IMO.

I agree 100%. It is not "JUST" inconvenient, as some might think, it is a safety issue. Do you watch the road/track or the display to find out which gear you are in? Because it REALLY maters how you go through the turn if you have power= 3 gear or none= 5th gear. The second problem is that you never know if it it going to shift or not. I have had it shit a second later in the middle of the turn. I have had it shift into 2nd gear and go into overrev. I have had it shift to 6th. But usually just not at all, 5th is such a wonderful gear at 30 mph.
You(I) begin to watch the display instead of where I am going (a very bad idea). I am loosing confidence in the ability of the car to preform consistently in corners, which is TRULY a safety issue.

[skierman64]

I will have my DCT at the track in a month. I'll be severely disappointed if I have downshifting issues if I'm trying to downshift under braking.

[lucid]

Originally Posted by MarksM

The second problem is that you never know if it it going to shift or not. I have had it shit a second later in the middle of the turn. I have had it shift into 2nd gear and go into overrev. I have had it shift to 6th.

Ouch! These observations are not good at all. I don't understand why these issues have not been caught during testing. Maybe they were caught, but they were under pressure to deliver, so they released it anyway.

Unless BMW can clean this up within the next year or so, I'll shelve my plans for a DCT upgrade...

[MarksM]

Originally Posted by lucid

Ouch! These observations are not good at all. I don't understand why these issues have not been caught during testing. Maybe they were caught, but they were under pressure to deliver, so they released it anyway.

Unless BMW can clean this up within the next year or so, I'll shelve my plans for a DCT upgrade...

You can have mine pretty cheap if they don't.

[lucid]

Originally Posted by MarksM

You can have mine pretty cheap if they don't.

It'll still be cheap even if a software upgrade provides the needed fix?

Having said that, I'm thinking that if it was simply a matter of a software upgrade, they would have fixed it during testing?

[hakaida442]

Larry Koch should be let known about this problem. This is a dealbreaker for some people. Some porsche guys are unhappy about pdk controls being on the front of the steering wheel too. So far no one has the perfect paddle shifting tranny yet.

[Gearhead999s]

Originally Posted by hakaida442

Larry Koch should be let known about this problem. This is a dealbreaker for some people. Some porsche guys are unhappy about pdk controls being on the front of the steering wheel too. So far no one has the perfect paddle shifting tranny yet.

Ferrari does with the fixed paddles.So simple left for downshifts,right for upshifts,pull both for neutral.You always know where the paddle is when are turning,very simple!

[hakaida442]

Originally Posted by Gearhead999s

Ferrari does with the fixed paddles.So simple left for downshifts,right for upshifts,pull both for neutral.You always know where the paddle is when are turning,very simple!

for the track the f430 is great, but the auto mode for the street needs work. no one has the best of both worlds perfected yet imho.

[swamp2]

Guys, great observations, experimentation and documentation. Now get yourselves over to a good service advisor and SHOW them the problem. MAKE them take a report of the problem. Mention that you believe the issue to be a "SAFETY" issue. That will get their attention. Either way I would bet that all such reports will get elevated to a fairly high level since no NA BMW grease monkey will know a lick about M-DCT software and this is almost for sure a software issue.

I agree with lucid, it is really tough to believe that BMW M Engineers and test drivers would let such a thing make it to production. If the issue really is an intentional "nanny" it just doesn't make sense. How can they offer things like DSC=OFF and S6 modes then bring the nanny right back?

[footie]

Until I hear if the same situation is happening on any of the D modes or the lower S modes (1~4), I have to assume that it's a problem with S6. We know that the system is meant to stop the surge happening in corners but is it possible the same system is controlling the gearbox in other ways, less favourable ways.

Enigma said that D5 proved to be quickest but didn't say how the gearbox behaved during it's laps.

I would have thought with the extent of testing done by BMW that this problem must have arisen more than once.

[MarksM]

Originally Posted by footie

Until I hear if the same situation is happening on any of the D modes or the lower S modes (1~4), I have to assume that it's a problem with S6. We know that the system is meant to stop the surge happening in corners but is it possible the same system is controlling the gearbox in other ways, less favourable ways.

Enigma said that D5 proved to be quickest but didn't say how the gearbox behaved during it's laps.

I would have thought with the extent of testing done by BMW that this problem must have arisen more than once.

Oh, by the way it happens in S4 and S5 and S6. D mode is not related to this issue because you can't shift paddle mode in D it always reverts to S mode when you hit a paddle

[footie]

Originally Posted by MarksM

Oh, by the way it happens in S4 and S5 and S6. D mode is not related to this issue because you can't shift paddle mode in D it always reverts to S mode when you hit a paddle

So it's happening in all the mode with surge or is it the only modes that happen to have been try at the time?

P.S.
I know D mode wouldn't experience the same problems, I was only asking the question if any other behavioural issues where experience in it because for that mode to have been quickest on the day he must have been giving it stick.

[MarksM]

Originally Posted by footie

So it's happening in all the mode with surge or is it the only modes that happen to have been try at the time?

P.S.
I know D mode wouldn't experience the same problems, I was only asking the question if any other behavioural issues where experience in it because for that mode to have been quickest on the day he must have been giving it stick.

I have not tried it in S1-S3 because I saw no point, because I was looking for good uphifts also. I could become further distracted by both shifting down for the corners and reducing the S mode at the same time when entering a corner, then increasing the S mode upon leaving the corner or better yet at the apex. Hell I'm liking this transmission more and more. I didn't have enough other things to distract me from not dying.

[footie]

Mark,

It has yet to be comfirmed that the surge benefits the actual acceleration by that much anyway so why disregard them altogether. My point was more that until all modes are tried we don't know all of the facts about which settings are at fault.

[Mickb]

Originally Posted by footie

Mark,

It has yet to be comfirmed that the surge benefits the actual acceleration by that much anyway so why disregard them altogether. My point was more that until all modes are tried we don't know all of the facts about which settings are at fault.

Footie an awful lot of assumptions and speculation on your part in various posts above.

Firstly it happens in ALL modes.

Furthermore, your speculation about this preventing a surge during cornering doesnt make sense in this context...it is downshifting we are talking about......the surge doesnt come into play at all during downshifting.

I would be willing to bet this is a supposed "safety" feature that is engineered by BMW and triggered by ABS activation.

Only BMW can answer this.

[enigma]

Originally Posted by footie

Mark,

It has yet to be comfirmed that the surge benefits the actual acceleration by that much anyway so why disregard them altogether. My point was more that until all modes are tried we don't know all of the facts about which settings are at fault.

Actually I measured how much it helps this weekend. I just need to go through and clean up the data so I can post it.

[Pitkis]

Originally Posted by MarksM

I have not tried it in S1-S3 because I saw no point, because I was looking for good uphifts also.

I tried it in S2 and the situation was the same as in other modes. Also, I was under ordinary POWER and EDC, DSC full safe mode (due run-in).

[MarksM]

Footie,
I understand what you are saying about the surge and you are right. I would give up the surge for being in the right gear in the corner. Accelerating in a mystery gear to be determined is not very fun or safe.

[nusevad]

It would be nice if we could put the tranny in neutral like Ferrari if we pull both paddles.

[Mickb]

Originally Posted by FifthStreetz

It would be nice if we could put the tranny in neutral like Ferrari if we pull both paddles.

You can put it in neutral while rolling by pushng the shift lever to the left.