Based on research, I think I have it narrowed down to the flywheel, but I’m looking for your guys opinion before I make any moves.
'04 S4
~120K miles
So yesterday I’m driving back home from a car cruise over to Leavenworth, WA. Just cruising along pretty good through the mountains (Spirited driving, some aggressive), outside temps were around 80°F, everything else is normal as far as I can tell/feel. Got up behind some semi trucks, pulled out to pass them when it was safe, mashed the throttle and I felt a fairly decent vibration when I pushed in the clutch pedal to shift. It was also accompanied with a very low pitched humming noise, which I imagine was from the transfer of vibrations. There was no build up to it at all, it just all of a sudden started doing it. I could primarily feel it through the shifter and clutch pedal and a tiny bit through the gas pedal and seat, but nothing at all through the steering or braking. It would completely go away when I pushed in the clutch pedal or put it in neutral. Scanned for codes through the torque pro app and got nothing except for the o2 sensor codes I already had. I carefully drove it the rest of the way home and parked it.
Get up this morning and hook up vagcom, still no codes at all. Went and drove the car, and nothing. Drives smooth as butter. I let the car warm up completely to go do a couple pulls to see if I can duplicate the problem. I was able to get it to do it once at higher RPM, partially did it another time, and I can feel it a tiny bit in the seat when I rev it past 4k in neutral. Problem is, I cannot get it to consistently replicate the issue, so I can’t tell exactly what RPM it is occurring at or if its in a specific gear. Most of the reading I have done, it seems like people were having it occur across all RPM ranges, which is what it was doing yesterday when engaged in gear.
So am I on the right track here thinking the flywheel is giving out? If I drive normally, the car feels perfectly fine, but I obviously want to get this figured out before it possibly cracks the bell housing or worse. Only thing I did to the car before I left was replace the spark plugs and air filter and install 034 rear endlinks. Car shifts fine and clutch engagement feels normal.
Thanks in advance.