N or D - DCT

Discussion in 'M Power' started by The Livster, Jan 28, 2016.

  1. The Livster
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    The Livster

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    What do you recommend when stopping at lights etc. leave in Drive or move into Neutral ?
    If I think I will be stopped for more than a couple of seconds I usually put the gearbox in Neutral, is this necessary or should I just leave it in drive ? In my automatics I usually left it in Drive
     
  2. Mieke
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    Mieke WARLORD Site Supporter

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    I've considered the same question, as the 330d is the first automatic that I've owned. On manual boxes I would always select neutral at TLs to save wear on the clutch and thrust bearing. On the 330d I just leave it in Drive at TLs but on the odd occasion when I'm going to be stopped longer than a couple of minutes, I'll select N.

    I'm assuming that the ZF auto box is designed to remain in D for short stationary periods without causing problems? I take it the DCT box on the M5 is more of a semi-automatic transmission to handle all that power?
     
  3. The Livster
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    The Livster

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    The Auto is fine sitting in drive, not sure if the posts regarding it are on here or previous site , but well documented. Asked same question on PH and opinion seems to be DCT is also fine in drive, thanks for your reply (y)
     
  4. Spuffington
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    Spuffington Moderator WARLORD Site Supporter

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    Peter has covered this off many a time with very comprehensive explanations of how the gearbox deals with it these days. The upshot being - automatics, leave them in Drive all of the time, regardless of how long you're stationary. (y)
     
  5. markyboyt
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    markyboyt

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    If I stop at traffic lights in my auto I shift to park so I'm not dazzling other drivers by sitting on my brakes. In a manual I shift to neutral and put the handbrake on.
    In a DCT box I would leave it in drive but put the handbrake on and get off the brakes for the same reason if at red lights.
     
  6. Spuffington
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    Spuffington Moderator WARLORD Site Supporter

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    From what I recall, there's a danger if you're in Park for too long with the engine running, that the oil pump is potentially not engaged and that you'll ultimately ruin the box.

    When I'm in a similar situation, I just pop the handbrake on and leave it in Drive - again to prevent dazzling.
     
  7. markyboyt
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    markyboyt

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    In an auto or DCT?
    In an auto the oil pump is driven by the torque convertor outer casing either directly or via a chain so is mechanically linked to the engine permanently, in park the gearbox is in neutral so there is no load on the torque convertor and the car is held with a mechanical parking pawl in the gearbox locking the output shaft of the gearbox.
     
  8. Peter
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    Peter WARLORD Site Supporter

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    The whole concept of an auto is to put in 'D' and drive. There is no need and no technical benefit to putting it in neutral. Some in the business suggest it causes more wear to use neutral.

    The latest gear boxes are designed to activate an internal 'neutral' on idle, with the foot brake on, automatically. In the 6 & 8-speed ZF autos it is referenced NIC, (Neutral Idle Control). It offloads about 90% of the TC slip and automatically re-engages on moving off.

    We've always got the handbrake, if we don't want to keep the foot on the brake. Models with auto-hold (like the 5-series, including the M5 with DCT) the drivetrain looks after itself, takes care of all the functions, simply engage Drive and go. :)

    Peter
     
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  9. 21qazxsw
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    21qazxsw

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    I always put it in neutral when I'm waiting at traffic lights, etc. but that's just me. I have an E92 335i with DCT.
     
  10. Lucero
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    Lucero

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    I would have thought that Auto Stop/Start feature would negate the need for a conversation like this. I know ASS can be annoying in diesels, but in the M5 it's a charm and the gearbox stays in D all the time. There can be no damage the transmission waiting for long periods if the engine is off :)
     
  11. 21qazxsw
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    21qazxsw

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    I know.

    With Auto Start Stop, you have to keep your foot on the brake all the time. Highway Code says put the handbrake on and take your foot off the foot brake so as not to dazzle the driver behind you with your brake lights. I know nobody does that, but that's what the Highway Code says.

    Personally I don't like Auto Start Stop. I always disable it if I'm driving a car with Auto Start Stop. My current car does not have it, but my previous car (E92 320i 2007) did have it.
     
  12. Singvogel
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    Singvogel Moderator WARLORD Site Supporter

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    I have ASS on my 330d and don't find it annoying at all - now that i am used to it - it was a bit disconcerting for the first few days until I sussed out exactly when it would operate.

    How would it be annoying on a diesel and not on a petrol?
     
  13. Spuffington
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    Spuffington Moderator WARLORD Site Supporter

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    I'm also fine with it and can't understand what the fuss is about. Admittedly I turn it off if I'm in an urban environment where it's continually start-stop but I leave it on otherwise. I've got to the point with the X3 that I'm so used to it that when the Z4 doesn't turn off, I think something's wrong with it! :D
     
  14. 21qazxsw
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    21qazxsw

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    Surely that's the whole point of the auto start stop Mr Spuff??? :ROFLMAO:
     
  15. Lucero
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    Lucero

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    Just my own observations really but a diesel seems to crank a fraction longer than petrol and then hits you with a spot of lag while it tries to work out what it is you're doing :)
     
  16. Spuffington
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    Spuffington Moderator WARLORD Site Supporter

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    I think it's a balance between wear on the mechanicals, load on the battery and fuel saved plus the time taken to move away at a junction or something. In Saffron Walden, the traffic at school times particularly is dreadful. But you're never stopped for any length of time particularly. That means that it's constant stop & start. As opposed to if I were somewhere where the traffic is moving but then there's a set of traffic lights which has a longer stay.

    I have got reasonably adept at managing the pressure on the brake pedal. If you stop with minimal pressure on the brake pedal then the system will not stop the engine; only stopping it when you apply very firm pressure. This can help to manage a stop when you want it.
     
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  17. Singvogel
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    Singvogel Moderator WARLORD Site Supporter

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    Before I settled on the 330d I test drove several alternatives including a 330i and I have to say that I couldn't detect any difference in the restart between them.

    Perhaps with the M cars it's different of course.
     
  18. kleynie
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    kleynie WARLORD Site Supporter

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    If someone hits you from behind aren't you going to mince the gearbox? Surely neutral and handbrake is better?
     
  19. kleynie
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    kleynie WARLORD Site Supporter

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    But auto hold still applies the brake lights, thus dazzling the driver behind.
     
  20. Singvogel
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    Singvogel Moderator WARLORD Site Supporter

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    Doesn't the auto-hold just prevent the car from rolling backwards before you move off on an incline - for approx 2 seconds - i.e.after you take your foot off the brake until you put it on the accelerator.
     

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