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

aus335iguy

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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 ?
 

dyezak

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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.
 
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Blue335is

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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.
 

doublespaces

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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.
 

aus335iguy

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Are the m4 cltchpacks the same as the 335i ones though? I thought I read that they were different
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.
 

doublespaces

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Are the m4 cltchpacks the same as the 335i ones though? I thought I read that they were different

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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boostE92d

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I would agree. Failures have been so isolated.
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?
 

Blue335is

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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?
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.