Thread: DCT noises...
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      10-28-2012, 08:28 AM   #1
Asbjorn
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Cool DCT noises...

Hi all,

Is it normal that the DCT starts to make tiny clicking noises just before gear shifts when warm? [edit: No, this was because my gearbox was still leaking oil, see further down] (only audible with windows up and roof closed) I had my transmission repaired due to a small leak just after taking ownership of the car at around 25.000km, and I do not remember if it was there before changing oil pan and sealing. I worry if the dealer screwed something up...

Here are the noises that I hear from my DCT in order of volume.

1) the loudest noise is the clunk when engaging or disengaging D or R from/to N or P. I believe this is 100% normal and does not concern me. [EDIT: the noise probably comes from the differential. 2nd EDIT: after having the gearbox repaired, this sound now also seems to be less present]

2) there is also sometimes a similar clunk when bringing the car to a stop while the transmission in D. I believe this is normal as well and depends on how the brake pedal is operated around the speed where the creep function is active. I found that other users in here reported the same sound. Not a concern then. [EDIT: the noise probably comes from the differential]

3) finally I get two less audible noises. A few click/tick sounds just before a new gear is engaged and a turbinish whine which is modulated by the revs and seems to peak somewhere between 3000-3500 rpm and again above 5000rpm. Both noises are not there when the engine is cold! They start only after the engine oil temperature has been warm for some time. That is why I think it is related to the temperature of the transmission oil, which may reach higher temperatures only some time later than the engine oil. But I do not know. I think it starts only after +20kms of driving, but again, I am not sure exactly when. [edit: The ticking sounds disappeared after I had the DCT repaired again. The whine is probably related to the turbos...]

I have never had any warnings of the DCT over-heating, and it has always worked brilliantly. It is smooth as silk in normal, no matter if it is hot or cold, and it is fast, solid and punchy in sports and manual modes.

Are other Getrag DCT owners (which excellent ears) experiencing these noises?
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Little known facts about BMW: 1) The N54 is still in production and used in the current Z4 35i and 35is. 2) In a Z4 you can get sport+ steering combined with normal suspension etc by selecting DSC=off. (Update: DSC=off also offers sports steering in the M135i) 3) All Z4s with 19" wheels are still only offered with the worst performing OEM tires ever sold with a DCT equipped BMW (Potenza RE 050 RFT).

Last edited by Asbjorn; 11-29-2012 at 02:47 AM.