Possible Bad B6 Flywheel?

B6/7 S4/RS4
#1

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.

#2

If it’s the original flywheel and clutch units including the throw out bearing it’s a good chance it’s located as one of the problems. The 04 flywheels were very well known for loosing the bearings and falling apart. From what you said it completely sounds mechanical. If the vibration is more noticeable in certian rpm ranges that would indicate a balance issue and most of the time what you mentioned is the flywheel bearing going out.

#3

Well it sounds very possible that could be the issue. But as of now, I’ve driven the car a couple times and it has not done it at all. Everything feels normal. Ran the car up to redline getting on the freeway tonight in 3rd and it felt smooth, shifted fine, etc.

So as of right now I think I’m going to keep driving it until it happens again. Unless you feel otherwise. This is all I have to drive and I don’t really want to unnecessarily spend money dropping the tranny on a maybe. I have the knowledge/skills to do it myself, but not the time/space so I would have to take it to a shop.

I will update this if anything comes up.

#4

For now if you don’t feel anything after a few runs it’s a good sign. The reality is that sooner or later there is a very good chance that the bearing will fail. It’s very common on the 04 and 05.

Knowing that you can do it but now isn’t the time I would totally just try to wait until it was mandatory.

#5

Yes, I agree it will need to be done sooner or later, along with the clutch. I believe it is still the factory clutch, but I would have to dig out the service records from the PO to confirm that.

When the time comes, do you think it would be worth it to spend the extra money for the 1R clutch? or just go with the stage 3/4? I don’t have any plans to go forced induction, well not in the next couple years at least. Unless this thing takes a dump soon, I will probably be replacing everything this winter as I have some time off around Christmas.

#6

I just saw this post after making a post about similar symptoms!

My 05 S4 was working perfect and randomly started vibrating while going up hill. I drove it home parked it and scanned the car no faults, nothing is loose, my mounts are tight and the wheels are good.

The difference is my vibration is constant, it has not gone away. I can also feel it when in neutral and rev up the engine.

#7

If it’s worse at certian rpm ranges you might want to look into the flywheel

#8

Whelp, it totally took a dump last week so I parked it. Just dropped it off at this morning for a stage 4 clutch and lightweight flywheel. Should have it back by Friday. ;D

Guy who works there has a B5 with the RS6R turbos and all the JHM goodies. Gonna see if he will take me for a ride in it when I pick my car up.