2011 128i Clutch Issues

[white_averson]

So, when I got my 128i 2 years ago the clutch was slipping. Had just rolled 60,000 miles, seemed like it could have worn out by then. So, a year ago, I did a full clutch replacement. The old clutch looked suspiciously okay but I swapped it all. And sure enough, the clutch still slipped. The oil pan gasket was leaking so I thought the oil getting in the bellhousing was contaminating the clutch. So, this month I did the clutch again, along with the oil pan gasket. A real pain. And... it still slips.
Did I install something incorrectly on both clutch jobs?
Can improper torque specs cause a clutch to slip? Torquing the pressure plate and flywheel with the dual mass flywheel is a pain but I think they are close to spec.
Bad slave cylinder? Pulled the slave out and confirmed the fork has a half inch of free movement so there's no mechanical pressure on the pressure plate. Tried crack the bleeder to release potential residual pressure. That did nothing. Deleted the CDV and bled the clutch. The feel is better but it still slips. Losing confidence that the issue is hydraulic. Try a new slave? Its frustrating because I can't think of a way to confidently diagnose the culprit. The next would be the flywheel? The one half rotated quite a bit torquing the pressure plate but thats normal? Not excited to drop the trans again
It slipped immediately after both replacements. And was slipping before I replaced it the first time, though I wasn't paying attention to how it slipped at that time.
It slips when I'm in "too high" a gear and step on it. Think passing on the highway. If I drive it like I'm trying to get in trouble, it won't slip and if I baby it, it doesn't slip.

[white_averson]

Also the feeling is a shuddering, like its rapidly catching and slipping, that almost maintains revs when it does slip

[summitp]

Sounds like improper parts used or improper installation. Post up part numbers used.
Did you replace the flywheel? Was there ridging on the mating surface of the flywheel? I don't know about the clutches on these 1ers, but other w DMf can't be resurfaced and should be replaced as part of doing the clutch (didn't stop me from successfully refreshing the DMf on my 540i/6 with sandpaper...)

When you bolted up the transmission, did it align properly and seat against the back of the crank case without compressing the clutch? If it is slipping and correct parts are used, there is some interference preventing the pressure plate from engaging all the way.
Could be pp attached to flywheel improperly, Could be throw out bearing and release arm not disengaging all the way, (is there some obstruction on the guide sleeve it rides on?)
Is the release arm properly seated on the ball pin that it pivots on?
All these things could prevent the pressure plate from engaging all the way.

IF everything is assembled correctly AND you did not replace the flywheel (and did not have it resurfaced) this would be a suspect.

Post up the part numbers used and call out all clutch related parts used.

[white_averson]

So this last time I used

Luk clutch kit part # 21207587368

I didn't replace the flywheel on the most recent clutch job but I used

Luk part # 21207573785

On the first job along with the same Luk clutch kit.

Replaced the bellhousing, pressure plate, flywheel bolts. When I replaced the flywheel the factory one looked fine but I did it anyway. Transmission alignment seemed fine. The clutch fork moves when the slave is out so there shouldn't be anything compressing the clutch other than possibly the slave but that doesn't seem likely. I didn't replace the fork pivot pin. I should get the steel one. The release bearing guide tube seemed smooth and clean. I think I'm going to have to drop the trans again and inspect everything again...
I'm leaning towards the new flywheel being the issue? The slipping behavior is weird. I wish there was a way to confidently diagnose the culprit.

[white_averson]

Is it unusual for the friction face of the flywheel to rotate a significant amount when torqueing the pressure plate?

[summitp]

Hmmm. Clutch disc in backwards? Does the pedal return fully? I do think you are going to be doing a disassembly. Something is not right preventing pressure plate from clamping down 100%.

If nothing else you are gonna be the go-to person for all things 128i clutch related bout the time you get this wrapped up.

[white_averson]

I definitely am becoming more familiar than I would like with dropping the transmission. I'm pretty certain I put the disc in the correct direction. Pedal movement and feel seems normal if maybe a bit light. I guess I need to find the space to get this thing apart again.

[white_averson]

Well, I hung on to hope and bought a new slave and a pressure bleeder and did that this weekend. As expected, no change, so I guess I gotta drop the trans again. Trying to decide what to replace. I think the flywheel should be and I definitely need the fork pivot. Do I bother buying another clutch kit? Can the pressure plate be removed and reinstalled without the throwing star?

[white_averson]

As an update and conclusion, I'm clueless and was actually dealing with a misfire. Assumed because I wasn't getting a check engine light it was something else. Knocked out the valve cover gasket along with plugs and coils this weekend and now the car pulls through the rev range without any hesitations.