[boostm3]

Any new M2 owners experience a nasty resonance coming from the passengeer side rear at 3k rpms as you accelerate from 2500 rpms to 3500 rpms in third gear?

I managed to pin it down to the REAR passenger side seatback latch leading to the trunk.. When its latched, its noisy at 3k rpms in third gear; when its Unlatched, even resting against the latch, no such annoyance.

Its weird because normally, you would think that when the latch is under tension, ie closed, it would be buttoned down and when its unlatched, thats when youd expect to hear anything loose in the assembly.

But Ive got the opposite.. Ill have the dealer take care of it in 350 miles when I bring it in for the 1200 break-in service.

I hate resonances! So annoying, and chasing them down can be a real pain.. I always used to get them in my sport bike fairings when I used to ride.. Usually a shim made out of foam or rubber would quiet it. But this rear latch has me puzzled.

[MrKepan]

Congratulation! You found the "3k rpm buzzing" Easter egg BMW installed fresh from the factory.

Just kidding. Yes, I discovered it the 1st day when I took delivery. Mine actually turned out to be the triangle shaped metal loop in the trunk floor. I flipped it standing up and the buzzing is gone. The other day I was shopping and a box pinned it down again and the buzz came back.

Glad you found your source.

[Artemis]

Originally Posted by boostm3

REAR passenger sideseatback latch leading to the trunk.. When its latched, its noisy at 3k rpms in third gear; when its Unlatched, even resting against the latch, no such annoyance.

Do you mean the seat belt buckle ?

I noticed a metallic buzzing/humming right from day one around 2.8k rpm. Initially I thought that it was related to the MPE. It's somewhere in the back of the interior. Checked several times (rear seat belts, seat belt buckles, rear seat armrest, rear seat cup holders, rear seat trunk locks, rear seat headrests, speakers, rear panel, airco blower behind the front seats, etc.) but never managed to locate it.

Please post a picture of 'your' exact location.

[boostm3]

Originally Posted by Artemis

Do you mean the seat belt buckle ?

I noticed a metallic buzzing/humming right from day one around 2.8k rpm. Initially I thought that it was related to the MPE. It's somewhere in the back of the interior. Checked several times (rear seat belts, seat belt buckles, rear seat armrest, rear seat cup holders, rear seat trunk locks, rear seat headrests, speakers, rear panel, etc.) but never managed to locate it.

Please post a picture of 'your' exact location.

The buzzing is directly related to the latching/unlatching mechanism of the passenger side rear seat back. The rear seat back has a U shaped metal bracket which fits into metal jaws in the rear deck to 'close' the rear seat back.. When the seat back is pressed into those jaws in its normal closed position, I get the resonance.. Opening the jaws via the plastic handle in the trunk eliminates the resonance! You can fold the seat down if you like, or even leave it resting against the metal latching jaws.. Either way, on mine, the buzzing disappears.

Please let me know if you need a picture beyond this description. I cant say for sure its the metal latch that is buzzing, however I CAN say for sure when the rear passenger seat is closed in its normal position, it buzzes, and when its not in its closed, normal position, it doesnt. Strange but true.

BTW, I tried messing with the rear seat belt mechanism as that was one of my first suspects, but its definitely not that. Let me know if this jibes with what's buzzing in yours.

[M2wolf]

Got the same problem. Photos would be helpful. Thanks.

[mjsaville]

Is it possible to simply wrap the U shaped metal buckle?

MJ

[Lukeni]

Originally Posted by boostm3

Any new M2 owners experience a nasty resonance coming from the passengeer side rear at 3k rpms as you accelerate from 2500 rpms to 3500 rpms in third gear?

I managed to pin it down to the REAR passenger sideseatback latch leading to the trunk.. When its latched, its noisy at 3k rpms in third gear; when its Unlatched, even resting against the latch, no such annoyance.

Its weird because normally, you would think that when the latch is under tension, ie closed, it would be buttoned down and when its unlatched, thats when youd expect to hear anything loose in the assembly.

But Ive got the opposite.. Ill have the dealer take care of it in 350 miles when I bring it in for the 1200 break-in service.

I hate resonances! So annoying, and chasing them down can be a real pain.. I always used to get them in my sport bike fairings when I used to ride.. Usually a shim made out of foam or rubber would quiet it. But this rear latch has me puzzled.

Dude i love you for this! Got the same buzz and could not pin it down! Until now! <3

[boostm3]

Originally Posted by mjsaville

Is it possible to simply wrap the U shaped metal buckle?

MJ

Im guessing that's the issue; there must be some tiny 'slack' between the U shaped metal buckle and the latch mechanism creating a resonance/buzzing when closed. So, what kind of 'wrap' could be used? Im thinking tape would be scraped away by the jaws in the latch mechanism, as whatever 'slack' is present is probably tiny, and it could gum up the latch mechanism.. I still want to present this to the dealer in 400 miles for my inspection srvc, so Im just looking for a temporary 'fix' to keep from going crazy til then. I was just going to leave the rear seat back down, but Ill get even more noise in the cabin.

[mrcheezle19]

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

[boostm3]

Originally Posted by mrcheezle19

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

You, my friend, are a GENIUS! I had thought it was an issue with the seat back latch itself since when the seat back was pushed into the latch, the buzzing was heard, and when the seat back was folded down (latch open) it was silent.. but I think now that was a misdirection.. a faux pax.... a strawman, covering up the real culprit, that goddamn plastic child seat latch cover! The one on the driver side is snug with no play, but the one on the passenger side is loose as F with too much side to side play. You tap on int and you can just hear and feel how it cant wait to start buzzing and resonating at the right frequency.. Im not sure what the interplay is between that child seat latch cover, and the passenger side seat back latch itself as to why the unlatched seat would prevent that child seat cover from resonating, but all I know is when I placed a foam buffer in the area under the child seat latch cover to take up the slack/play, I could push the seat back into its latched position and finally, no buzzing!

I think in time the foam I used will compress and the buzzing will resume so Ill be looking for a more permanent solution, or just make this the Dealer's problem instead.. Thanks for ferreting out the real instigator!

[SeanWRT]

Originally Posted by boostm3

You, my friend, are a GENIUS! I had thought it was an issue with the seat back latch itself since when the seat back was pushed into the latch, the buzzing was heard, and when the seat back was folded down (latch open) it was silent.. but I think now that was a misdirection.. a faux pax.... a strawman, covering up the real culprit, that goddamn plastic child seat latch cover! The one on the driver side is snug with no play, but the one on the passenger side is loose as F with too much side to side play. You tap on int and you can just hear and feel how it cant wait to start buzzing and resonating at the right frequency.. Im not sure what the interplay is between that child seat latch cover, and the passenger side seat back latch itself as to why the unlatched seat would prevent that child seat cover from resonating, but all I know is when I placed a foam buffer in the area under the child seat latch cover to take up the slack/play, I could push the seat back into its latched position and finally, no buzzing!

I think in time the foam I used will compress and the buzzing will resume so Ill be looking for a more permanent solution, or just make this the Dealer's problem instead.. Thanks for ferreting out the real instigator!

Originally Posted by mrcheezle19

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

Can you guys post a picture of the children seat latch system you're talking about? I had this buzz too back in summer, it seems already gone but I need to be sure. Thank you!

[look585]

I pinned it down to rear window shelf. Very noisy over bumps. My car is getting its 1200 mile service and asked the service adviser to take a look at it.

If you tap the right side speaker cover you'll see what I'm talking to about.

[boostm3]

Originally Posted by SeanWRT

Can you guys post a picture of the children seat latch system you're talking about? I had this buzz too back in summer, it seems already gone but I need to be sure. Thank you!

You cant miss it.. Its behind the head rest in the rear deck. You can see it clearly if you look down from the outside rear window or crawl onto the rear seat and look in that spot. Theres one behind each head rest right next to the rear speakers.

[gmzanatta]

Originally Posted by mrcheezle19

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

OMG YES 1000X THIS!!!!

It's been well over a year and I could never figure out where it came from, like others I thought it was the seat latch. A little bit of felt this morning and no buzzing on the drive to work.

[M2wolf]

Photos with the fix would definitely help!

[CommitConfirm]

I never hear this as I'm only in 3k rpm on my way to the redline. #flatout

[boostm3]

Originally Posted by CommitConfirm

I never hear this as I'm only in 3k rpm on my way to the redline. #flatout

It doesn't happen when cruising at 3k. With mine you have to be in third and accelerate fairly hard THROUGH 3K.

[hoyasaxa]

Saved for later

[Artemis]

Originally Posted by mrcheezle19

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

Originally Posted by SeanWRT

Can you guys post a picture of the children seat latch system you're talking about? I had this buzz too back in summer, it seems already gone but I need to be sure. Thank you!

Originally Posted by boostm3

You cant miss it.. Its behind the head rest in the rear deck. You can see it clearly if you look down from the outside rear window or crawl onto the rear seat and look in that spot. Theres one behind each head rest right next to the rear speakers.

In the past I also checked the latch child restraint mounting points (for tether strap anchors) behind the backseats, when searching for the resonance location, but that was when I had parked the car. Will check those mounting points again.



part #4: (source: here)

[boostm3]

Here's a pic of the child seat latch.. Youre looking at the latch cover which is the resonator. Underneath is a U bolt that the child seat hooks onto. I didnt want to open the cover which just pops up because the 'fix' I employed is tenuous at best and didnt want to disturb it til I come up with something more permanent.. However all I did was stuff a bunch of foam in there to keep the lid from rattling. The 'trick' if there is one is to stuff enough junk in there to remove the play but not so much it doesnt close. The driver side one doesnt have this problem on mine because theres much less play in it. I think the proper fix would be for the dealer to replace the lid, and if thats not a separate part, replace the whole assy.

[boostm3]

Update..... Back to square f'in 1 Im afraid.. I thought I had it nailed; sure it was either the cover of the rear child seat lock pass. side, or the cover of the rear pass. side C pillar, or a combo of both, as both tended to be loose and have play in them such that when you tapped them with a finger you can feel it.. So, I shimmed both, and it was silent for months.. Last night, it came back

So I repadded the child seat latch cover such that there was zero play in it, and was tight as a drum but the resonance was still there. So I removed it completely, and not sure yet if even that took care of it. It seemed to, however Ive been bitten before my false solutions.. Seems it may be affected by temperature or humidity or both, as it keeps coming back after going away for periods of time.

Chasing resonances is certainly a mixed blessing until the cause is finally found and removed. Cant even have the dealer look at it since its so sporadic.

[akkando]

Originally Posted by mrcheezle19

My resonance was coming from the child seat latch system above the headrest. I simply put some felt tape on the underside on the plastic lid and the noise stopped.

Yes I had this and used felt tape to solve it. I also have a rattle near the rear view mirror on certain bad roads, and also one driver side seat belt pillar area. I can only solve the mirror one but not sure about the pillar.