Rumble/Vibration from the rear when WOT on a tune
Someone else asked a similar question in the forum Whose Name We Dare Not Speak ...
Does anyelse here get a subtle vibration and hum from the rear of their car when WOT in 4th, 5th, and 6th gear? (only when running a tune)
I have had this problem in both of my 6mt 335i's. The one I have now is on its third diff (first one replaced under warranty for whine, second one replaced with Wavetrac LSD) and it still does it. Some in the other forum suggested it could be something to do with the gap in our spark plugs, given the added power.
I have a clunk coming from my rear subframe bushings, and so I ordered some powerflex inserts to eliminate that. My suspension guy suggested that the rumble could be coming from the axles, because everytime the rear subframe moves, the angle of the axles changes as it sits in the rear diff, apparently he thinks that could cause some "harmonic" issues.
Has anyone else had this issue? Do you live with it, or what did you do to fix it?