6MT - Clutch chatter when engaging 1st & 2nd at low RPMs

[chitown18]

Hi all- I've searched extensively, and while there is some mention, I didn't find alot specifically about this sound. 2012 E92 6MT ZCP. 38k miles.

This is NOT the idle rattle (with clutch engaged) while stopped.

This sound happens when you are engaging 1st or 2nd gear at low RPMs. As the clutch begins to grab, there is a subtle chatter. It seems less subtle when the car is very warmed up (louder, more consistent). Call it a chatter, a rattle, a flutter, a golf ball going into a plastic hole, pigeons in your transmission, or the sound of kicking a door stop at your home. There is no slipping problem. It still seems smooth enough, though perhaps I've lost touch with how smooth is SHOULD be. It's mostly a subtle nuissance that just doesn't feel "right."

Anyone have this? Had it fixed? Know what it is?

This is the best video I could find with the exact sound audibly reproduced- from and E46 M3:

Things I've seen mentioned: throw out bearing, input shaft bearing, dual mass flywheel, glazed clutch disc, loose springs in the clutch disc, misaligned clutch assembly, unevenly worn flywheel surface, etc. But which is it? And is it worth trying to get fixed or just lived with? And would it be warrantied?

Thanks in advance for any help!

[Konig]

Mine does the exact same thing, this is the thread I found about it.

http://www.m3post.com/forums/showthread.php?t=1052413

[thekurgan]

It's the dual mass flywheel coming to a stop. There is a certain amount of variation in the amount of free play the DMF can have, the wider the variance, the louder it seems. For the most part, it's a normal sound.

[V8FunNaturally]

dual mass flywheel. It's normal. Here is my explanation :

dual mass flywheel (DMF) are made of two wheels connected by a set of springs mounted circularly. under load when the engine is pulling the car the two parts of the flywheel make a constant angle that is proportional to the torque. As you press down the clutch pedal, the flywheel is no longer loaded and those springs shoot the energy they had stored moving the second wheel back in angular alignement ( 0 degree) with the engine shaft that drives the primary side of the flywheel. Being very powerful springs they oscillate the second flywheel for a brief moment which you can hear. There are no shocks absorber like car suspensions. The DMF reduces vibration coming from the engine which improves the ride and reduces wear in the drivetrain (including the clutch itself and gears).

This animation shows the dual mass flywheel. The yellow marker shows angular deflection from 0 degree and is proportional to instantaneous torque. Throughout the animation shows acceleration from the car stopped and then under various acceleration loads but not the above but it's enough to understand.

damn youtube is blocking the video and this forum robot is refusing to show the link with http !
youtu.be/MfNjARZc5Wo

[SenorFunkyPants]

Could be the DM flywheel has a broken part...there have been failures before.

[V8FunNaturally]

Originally Posted by SenorFunkyPants

Could be the DM flywheel has a broken part...there have been failures before.

Then it could be one of the springs in the DMF. Check my post before yours, you may have missed it since we posted at the same time.

[chitown18]

Thanks guys! Great vid of how a dual mass flywheel works too!

The physics of the flywheel and the sounds I hear definitely make it seem plausible that the chatter is caused when loads are either placed or removed from the flywheel causing one mass to bounce back and forth on the springs (it does also happen if you push in the clutch pedal quick while driving in 1st).

I guess I'm just looking for that next level of certainty, so that I can know what is normal versus what may be excessive or a damaged flywheel. For the people who say it is normal, how can we know whether we don't all just have damaged flywheels? I didn't have this car new so I can't know whether it happens on even brand new M3's, you know? I can't find anything definitive documenting the sound, attributing it to the dual-mass flywheel, and stating that it is normal. On the other hand, I can find lots of cases documenting the idle rattle and successful resolution after replacing the throw out bearing...

[thekurgan]

Originally Posted by chitown18

Thanks guys! Great vid of how a dual mass flywheel works too!

The physics of the flywheel and the sounds I hear definitely make it seem plausible that the chatter is caused when loads are either placed or removed from the flywheel causing one mass to bounce back and forth on the springs (it does also happen if you push in the clutch pedal quick while driving in 1st).

I guess I'm just looking for that next level of certainty, so that I can know what is normal versus what may be excessive or a damaged flywheel. For the people who say it is normal, how can we know whether we don't all just have damaged flywheels? I didn't have this car new so I can't know whether it happens on even brand new M3's, you know? I can't find anything definitive documenting the sound, attributing it to the dual-mass flywheel, and stating that it is normal. On the other hand, I can find lots of cases documenting the idle rattle and successful resolution after replacing the throw out bearing...

TOB bearing is an easy diagnosis with the clutch out (pedal dow) and the noise present. If you want to see if it's the dmf, let the car idle in neutral, clutch in (pedal up), and then turn off the ignition, you should hear the same "clack clack clack".

[12mpgm3]

I have had a similar issue for some time but it has gotten worse. What I have is NOT the "press the clutch in and it suddenly chatters" (that is normal operation of these clutches it seems and can be compensated by deft use of the throttle). For me this is starting from a stop in 1st after car is warmed up particularly when cold out. No matter how gently or moderately aggressively I engage, there is chatter, some slipping, and a hard grab. I have 32K miles, stock car, driven hard but never abused. I just brought it in the second time to dealer (who couldn't reproduce first time!) and had shop foreman drive with me and he said not at all normal and is going to pull the transmission. The clutch is fine engaging other gears while moving and the clutch is rock solid (no slipping under any load / condition when moving). May be several days until I get the car in but hoping this is one of those situations where they find something was broken / not operating properly, replace everything and give me a bill with a zero balance due!

[Ashbc]

I had the same chatter clatter from my 08 6mt M3, I had it diagnosed, not sure how reliable the Bmw specialist was but he said it's the Internal components on the gearbox.. Never got around to fixing it because someone body decided to plough into me and write it off.. Good luck, I can guarantee its not a normal problem, don't get fobbed off with "it's normal" 100% not normal

[villillo]

Originally Posted by chitown18

Hi all- I've searched extensively, and while there is some mention, I didn't find alot specifically about this sound. 2012 E92 6MT ZCP. 38k miles.

This is NOT the idle rattle (with clutch engaged) while stopped.

This sound happens when you are engaging 1st or 2nd gear at low RPMs. As the clutch begins to grab, there is a subtle chatter. It seems less subtle when the car is very warmed up (louder, more consistent). Call it a chatter, a rattle, a flutter, a golf ball going into a plastic hole, pigeons in your transmission, or the sound of kicking a door stop at your home. There is no slipping problem. It still seems smooth enough, though perhaps I've lost touch with how smooth is SHOULD be. It's mostly a subtle nuissance that just doesn't feel "right."

Anyone have this? Had it fixed? Know what it is?

This is the best video I could find with the exact sound audibly reproduced- from and E46 M3:

Things I've seen mentioned: throw out bearing, input shaft bearing, dual mass flywheel, glazed clutch disc, loose springs in the clutch disc, misaligned clutch assembly, unevenly worn flywheel surface, etc. But which is it? And is it worth trying to get fixed or just lived with? And would it be warrantied?

Thanks in advance for any help!

Hey did you find solution to this? My car is currently doing same 2011 zcp 6mt

[monterey]

Sounds like a hot spot on the flywheel.

[abeardo83]

If it's what i think it is, it's normal. It's a combination of the DMF and the slack in the drivetrain being taken up. I used to get the same in my S2000, alongside my M3.

[TX]

yep normal clutch chatter on slow on/off release ... mine does it..
i actually have chatter sitting still where the clutch is chattering just at red lights etc...totally normal

[Rajmun340]

As is the case with bmw, they often provide insufficient documentation to determine key technology for easy diagnostic outside the dealer and most dealer's are highly incompetent, unwilling and uninterested in solving customer concerns. If at least bmw was intelligent enough to provide more technical details we could DYI diagnosis things like this. There are many kinds of DMF clutches . All we know is this flywheel is hydraulically damped based on the E60 M5 manual 6MT that it came from. The chatter or chuckle noise could be from the the damping effect disappearing when the secondary side is either coming to a stop of just starting to turn and the arc spring becomes a noisy pendulum until rotation is fast enough (or comes to a stop) for the damping effect to eliminate it which takes a second. Most likely it's normal. Conventional manual gearbox are not DMF and will not have that noise. DMF is superior for isolating engine vibration to the gearbox and drive train. This is a minor side effect of that technology. Still, there are moving parts, springs and guides so it's possible some secondary part has broken without causing any trouble except for the slightly annoying brief noise. What i know is that gearbox is not repairable they change it whole or leave it.

http://www.luk.com/remotemedien/medi...techniques.pdf

[///BMW Junkie]

I purchased my 08' with 25K miles back in June. Thus far this clutch rattle was the only thing I was disappointed in. I mean it's pretty loud. Took it to one of the best independent shops in DC area and was right away told not to worry about - that the noise is normal due to the tranny/clutch type. My car has yet to see the dealership for a second opinion, but seeing other people having the same noise makes me think it's probably normal.

[E90Mthusiast]

Both mine and a coworkers M make this exact noise consistently, so I'd think it's totally normal. I actually kind of like it? These cars are known for having a somewhat clunky drivetrain.

[rsproject]

Originally Posted by thekurgan

It's the dual mass flywheel coming to a stop. There is a certain amount of variation in the amount of free play the DMF can have, the wider the variance, the louder it seems. For the most part, it's a normal sound.

You are talking about low RPM yes? what is the sound is at about 4k rpm when shifiting from 1st to 2nd ? thank you

[STooK]

Originally Posted by rsproject

You are talking about low RPM yes? what is the sound is at about 4k rpm when shifiting from 1st to 2nd ? thank you

Sounds like a totally different issue to me. Mine makes this noise only when I'm trying to get the car rolling from a stop in 1st. If it's doing it when you're shifting at 4k rpm, maybe you're not depressing the clutch all the way?