DCT Dual Mass Flywheel Dissection

doublespaces

Administrator
Oct 18, 2016
9,050
4,158
0
AZ
Ride
2009 E93 335i
A lot of people have heard about the issues which arise from using the factory dual mass flywheel in high horsepower situations. It is theorized that the extra weight on the flywheel knocks around causing vibrations, frequencies and noise that causes false knock in cylinders 5 and 6.

The solution is to purchase the M4 flywheel, which is still apparently a dual mass flywheel but it is missing the extra weight. @[email protected] decided to cut this weight off, but noticed that it was seeping a substance and did not take it any further. There have been reports that modifying the flywheel by cutting off the weight does indeed help, and there have also been reports that it does not. To get to the bottom of this, part of that requires we open up the flywheel and see what is inside. Jesse was kind enough to donate his flywheel to the cause and sent it up to Andy @AD-ENG for me to have it cut open. Here is what he found:

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Now I wonder what the M4 flywheel looks like inside.
 

aus335iguy

Colonel
Nov 18, 2017
2,086
717
0
Down under
Ride
335i DCT 2009
The harmonics generated by that thing swinging at upwards of 6and 7krpm would be fricken diabolical.

No wonder there’s issues