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DCT Failures and what we’ve learned....

Discussion in 'BMW DCT - GS7D36SG' started by aus335iguy, Feb 13, 2018.

  1. aus335iguy

    aus335iguy Lieutenant

    Messages:
    692
    Ride:
    335i DCT 2009
    So theres now two DCT failures that i know of. I think that the illusion that these things are unbreakable is now, well, broken :)

    First one was a local guy and basically the TCU stopped communicating with the DME and the car wouldn’t start. I have that TCU its the one that ive taken phots of etc. Basically the the car was fairly mild with only minor mods. No root cause was found.

    Second was a failure whilst doing a launch. Car is in the high 600’s power wise. Running a single, with drag slicks and upgraded clutches. Had MHD flash tune by pure evil, JB4, had two step and antilag etc. Car had the 135is flash and was being launched when it short shifted a couple of gears then revved out. Some suggestions that the JB4 was the cause, could be?? But slippage is pretty easy for a tuner to see in logs ...

    Quote from the facebook post ...
    I need some help guys, I have a 2012 335is with the dct transmission with a 135 flash (3500rpm) and ssp clutches, I was heading to the drag strip so i was testing out the launch. I did one launch and spun the tires pretty bad so I decided to do a better burn out the proceeded to do another launch.. the car hooked up pretty well she short shifted into second on its own at about 5k even tho it was in manual mode then it shifted to third gear then went to forth and the car went straight to the rev limiter like there was no gear at all and when I came to a stop the car stalled kinda like how a manual car would stall if you didn’t push in the clutch and left it in gear, went to restart the car and it started lurching forwards so I pulled out the Allen wrench and manually put the car in neutral was able to restart the car and limp it home but the car would only use odd gears it would skip over the even gears shift from first to third and so on when I got the car home at least it did not stall when I stopped it would idle like normal, I check the fault codes and I have codes p188d and p188e and I can not find much of any information on these codes any insight on my issue would be helpful thank you


    So.... other than if you play you pay, what can we learn from all of this ? What other failures have we heard of and what were the causes and fixes? DOes any one have any error codes and translations they can share ?
     
  2. dyezak

    dyezak Major

    Messages:
    1,692
    Location:
    Plano TX
    Ride:
    335is
    Oh, I did some testing and found that if DSC isn't completely off (i.e. you have it half off for launch control), after the 1-2 shift in M mode if you lose traction the DCT will short shift to 3rd, and if you still lose traction it'll short shift to 4th.

    DSC completely off eliminates this behavior, but prevents the use of launch control.
     
  3. Blue335is

    Blue335is Specialist

    Messages:
    56
    Ill have to find the photos but there was one gentleman I spoke to who destroyed the dct in a S55 m3 I believe it was. They pulled the trans apart and this so far is the only dct failure I've seen where the actual gears were stripped of their teeth. Considering its the only unit weve seen where the actual transmission failed Im assuming it was a manufacturer's defect.
     
  4. aus335iguy

    aus335iguy Lieutenant

    Messages:
    692
    Ride:
    335i DCT 2009
    Wow, what were the circumstances of the failure ? Power level? Was it tracked or ?
     
  5. Blue335is

    Blue335is Specialist

    Messages:
    56
    Bolt ons and a tune, with stock turbos on a drag strip. Like any good drag racing failure it all went wrong in the first 60 feet.
     
  6. aus335iguy

    aus335iguy Lieutenant

    Messages:
    692
    Ride:
    335i DCT 2009
    Yep the Achilles heel in every go fast plan... the first 60
     
  7. brandon818

    brandon818 New Member

    Messages:
    8
    Ride:
    335is
    I was going to have pure evil make a custom map 6 for me, now im scared lol
     
  8. doublespaces

    doublespaces Administrator

    Messages:
    6,243
    Location:
    AZ
    Ride:
    2009 E93 335i
    I know about steve nestore. Some of you may know him as lostmarine. His dct ate some teeth in one of the gears. Clutches went out first. Then driveshaft. Then teeth. @BMWJunkie is the one who told me.

    Also rk tunes says he can get the stock clutches to hold 700wtq in the m4 i believe.
     
  9. aus335iguy

    aus335iguy Lieutenant

    Messages:
    692
    Ride:
    335i DCT 2009
    Are the m4 cltchpacks the same as the 335i ones though? I thought I read that they were different
     
  10. Blue335is

    Blue335is Specialist

    Messages:
    56
    Jason at pure evil will take car of your car. We literally have listed ever get failure we are aware of on this thread. It' beyond rare.
     
  11. doublespaces

    doublespaces Administrator

    Messages:
    6,243
    Location:
    AZ
    Ride:
    2009 E93 335i
    No idea, I do know that the F chassis uses a different communication system, (BN2010) so there are some differences at least in the way the transmissions communicate.

    And here are the photos of the S65 DCT failure from Steve:

    gear_zpsiaqz50a7.jpg IMG_20150408_151509_711_zpsh1qz6mp5.jpg
     
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  12. Blue335is

    Blue335is Specialist

    Messages:
    56
    Yeah that' the only photos ive ever seen of a true dct failure.
     
  13. LMB335is

    LMB335is Corporal

    Messages:
    182
    Location:
    FOB FL
    Ride:
    13 335is
    Damn, that's impressive! That shaft is just sheared in two.
     
  14. Nisse Järnet

    Nisse Järnet Private

    Messages:
    39
    Ride:
    BMW E30 turbo 4wd
    Yes, all BMW DCT share the same clutches.
     
  15. boostE92d

    boostE92d Corporal

    Messages:
    123
    Location:
    Houston TX
    Ride:
    12 335is
    Manufacturing defects happen... I'm just saying.
     
  16. Blue335is

    Blue335is Specialist

    Messages:
    56
    I would agree. Failures have been so isolated.
     
  17. boostE92d

    boostE92d Corporal

    Messages:
    123
    Location:
    Houston TX
    Ride:
    12 335is
    To me that points even more to a defect, but we will see. More and more people are pushing dct turbo cars but the m3 guys have been going fast for a long time. What kind of failures have they had?
     
  18. Blue335is

    Blue335is Specialist

    Messages:
    56
    This one failure I'm referencing was from an m3. There's not enough cases of actual trans failures to conclude anything. The hundreds that have been pushed hard in the bmw world have not failed with the exception of one or two cases.
     
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