1. Intel iGPU (6xx series) crashes
    Fixed drivers available!
    Instructions here

    Dismiss Notice
  2. Before reporting issues or bugs, please check the up-to-date Bug Reporting Thread for the current version.
    0.19 Bug Reporting thread
    Solutions and more information may already be available.

DCT shift time inconsistency

Discussion in 'Troubleshooting: Bugs, Questions and Support' started by default0.0player, Oct 3, 2019.

  1. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    This happened more or less in every DCT vehicles, both the upshift and the downshift time is not consistant.
    Note the M number changes and the RPM gauges. The 200~500ms lag is noticeable, especially during downshift. It would be better to leave the shift lever in D in non-aggressive driving, only use M in racing, where the lag is less likely to happen.
    ssssssssssssssssssssssssssssssssssssssss.png
    Check out the videos in the attachment
     

    Attached Files:

    • Agree Agree x 1
  2. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    DCT shifts are not immediate as it first needs to make sure the second part of the gearbox is in the right gear. So depending on when and how you shift it's not in the gear you want to shift to and takes longer to shift.
     
  3. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    Understood. However another thing is the rev-match is not synchronized when the downshift is delayed
     
  4. _Tanco

    _Tanco
    Expand Collapse

    Joined:
    Jan 7, 2017
    Messages:
    216
    Im gonna do a video later, my problems is that the engine do some "jumps" of RPM while downshifting several speed, I didn't saw @default0.0player's videos but his description looks pretty close to my problem (I will try to show it later in a video, im not on my computer right now)
     
    • Like Like x 1
  5. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    The thing is when the preselected gear is not matched, the shifting time is delayed(not a bug), BUT the rev-match throttle time is not synchronized with the delay, which leads to a noticable jerk in some downshiftings.
     
  6. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    Hm, that sounds like it's not possible, it should only revmatch when it's ready to shift. You are probably seeing something different. But yea, multi-downshifts are a bit rougher than I'd like them to be, I'll take a look again. :)
     
    • Informative Informative x 1
  7. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    A good way to recreate this is to drive a DCT vehicle at M2 at a constant speed for a few seconds where the RPM is in mid-range such as 3500, then downshift to M1. The TCU probably preseclect to 3rd gear so shifting to 1st is delayed, then the mismatched rev-match throttle will be noticed.
     
    • Like Like x 1
  8. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    Interesting, that is something completely different to what I mentioned, thanks for the tip.
     
  9. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    Oh, steady RPM as well, ok, I was under the assumption we were speaking about full load/aggression things.
     
  10. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    Not always appeared at a steady RPM, but a steady RPM is the most likely to recreate the phenomenon and easy to observe
     
  11. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    Alright. I'll see what I can do. Overall I'm not really happy with how the DCT works and stuff, but it's a surprisingly difficult topic....
     
  12. _Tanco

    _Tanco
    Expand Collapse

    Joined:
    Jan 7, 2017
    Messages:
    216
    I don't know what default player is talking about (but it seems really relevant !), but the problem I was talking about is this :
    The Sunburst's DCT works better than SBR4's one, they both have the same problem but the DCT6 upshift and downshift a little bit smoother than the DCT of the SBR4
    (btw i think the gearbox agression reduce too slowly but that's a personnal opinion) @Diamondback
     
    • Like Like x 1
  13. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    762
    Here's the video, the clutching and the rev-matching are not synchronized.
    I also discovered some other problems.
    1. In D, shifting form 1st to 2nd gear is always above 3000 RPM regardless of throttle aggression
    2. The 1→2 shifting time is about twice the time of 2→3 or 3→4.
     

    Attached Files:

    • Like Like x 1
  14. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    That might just be the lowest rpm it's told to shift at, after all this is all still configured in jbeam.

    That's expected, it takes the gearing difference into account for how quickly to shift. (ie higher difference -> slower shift)
     
  15. Diamondback

    Diamondback
    Expand Collapse
    Moderator
    BeamNG Team

    Joined:
    Apr 8, 2014
    Messages:
    1,584
    Apart from that the other issues look like overshoot of the rev matching more than anything else, "rev match" might be the wrong term really, it's more of a "rev blip", it just presses the throttle a given percentage while the rpm is not high enough.
     
    • Informative Informative x 1
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice