10-27-2016, 03:25 PM | #67 |
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I heard the crunch noise again this morning after have the bumper PPF installed. Warm shop to cold rainy parking lot and coasting forward.
I'm inclined to believe this is not the diff and either the brake dust shield or underside heat shield flexing. In every one of my cases I don't think it was related to having a rock caught as it sounds more like metal flexing vs scraping |
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10-27-2016, 04:04 PM | #68 |
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Has ANYONE had any luck in getting a BMW service rep or dealer to acknowledge this noise, the cause, and a fix? I took my car in for the 1200 mile inspection, had experienced the noise 11 times in 1200 miles, and the dealer claims no one else has experienced it, that there are no bulletins from BMW about the noise, and therefore, basically treated my like I was crazy. Obviously from the number of people on this forum reporting it, the noise and its cause is fairly widespread. I'm really puzzled why BMW seems not to have acknowledged this yet. Yes, the car is drive-able, but I'm starting to get concerned. SOMETHING metal on metal is going wrong and that can't be good.
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10-27-2016, 04:32 PM | #69 |
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Just the axle-back exhaust and midpipe mating.
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10-29-2016, 05:27 AM | #70 | |
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The problem is that we cannot reproduce it. It could be anything. MR |
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10-30-2016, 02:07 AM | #71 |
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Took delivery of my M2 on 10/27. Before leaving the dealer, I asked if my week 38 production M2 was subject to any recalls or TSBs - specifically the diff and/or rear axle bolt. They said no.
I drove home from Oklahoma to California (the scenic and twisty way -- 1600 miles). Just for the record, I heard the soda can crunch noise a handful of times -- sometimes it sounded like it came from the left rear, and sometimes from the right. Usually at low speed. I'll keep my eyes and ears open, but am not overly concerned at this point. The car is amazing, and performed beyond my (high) expectations. |
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10-30-2016, 11:05 PM | #72 |
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Got the car on Oct. 25 after a one year wait. About 100 miles later heard a loud noise in the back that sounded like two non-lubricated metal plates being ground against each other. Sounded like 3-4 distinct grinds. Was going about 15-20 mph slowly merging to a turn lane but not really turning yet. Once I actually started turning the noise was gone. Stopped and checked for rocks in between rotors and the heat shields but saw nothing. Took the car to the dealer. They raised it up and said that they removed a few rocks, including one from the hand brake area (not sure how that would get there). They told me that they get at least a few M cars each week with that issue from new owners. Hopefully that's what that was as the car is not subject to the differential recall. I wonder how much damage does the rock grinding do?
Other than that weird quirk, the car is fantastic. The stock exhaust sounds great! |
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10-31-2016, 10:24 AM | #74 |
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So this is what this horrible sound is. I've been hearing this on and off since I purchased the car back in July. I always thought it was a car or truck that pulled up beside me. It is in fact quite loud and it is definitely a soda can crunch like noise.
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10-31-2016, 11:13 AM | #75 |
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Can crunch like noise on MT shifts?
I can swear I hear the soda crunch sound when changing gears but only if mismatch revs i.e as if trying to "chirp" the tires. Obviously I have a 6MT and it is most obvious when I upshift aggressively and the revs are not perfectly matched (usually a bit higher than the rev match would like)
At first, for several weeks, I thought it was the muffler flap opening and getting louder as part of some sort of computer engine modification to rev match but I have heard the random soda can crunch sound and it sounds very similar. The more I think about it I believe it comes from the differential. It only lasts 1/2 second. Once the revs match the rear wheels engage Almost as is the differential clutches are not engaging initially with the increased drive shaft rotation speed ? willfully? or otherwise protecting the wheels from breaking loose. No DCS light in case you wonder. Once the diff engages I can break the tires and DCS light will come on. I get the same noise if I depress clutch ( while car is moving), rev engine a bit, and drop the clutch. Get a crunchy noise from diff, tires wont break loose. Not that I am beating on the car but just mismatching revs by 1000 rpm or so. My car is may 30 build and I am affected by the diff recall. Got call from dealer. Will get new diff Nov 8th. Curious if anyone else has noticed this noise when shifting aggressively (not necessarily only when trying to chirp tires) with the manual tranny. BTW Since 1977 all my DD vehicles have been manual so I am not a manual noobie missing or blowing shifts! |
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11-02-2016, 01:44 AM | #76 |
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Heard it yesterday for the first time but it happened 3 times on a very short interval. Crunching a soda can is exactly the way to describe it. Late August build.
Happened when turning at low speeds.
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11-02-2016, 02:07 PM | #78 |
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Took it to the dealership today and they suspect it is the brake dust shield on the left side. They ordered a new one and will replace it when the part arrives.
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11-02-2016, 03:14 PM | #79 |
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It's not, the shields do not touch the rotors.
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11-02-2016, 03:17 PM | #80 |
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Right. According to them, one of the shields in my car is actually too far apart from the brake disk and debris gets trapped in the gap causing the noise.
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11-02-2016, 05:36 PM | #81 | |
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Keep us posted whether the noise still occurs after brake dust shield replacement.
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11-03-2016, 03:49 AM | #83 | |
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I am also not very convinced that it is the cause of it but I must say that incidentally the day when it happened 3 times in a row was a rainy day and I had been driving on a road with loads of loose dirt and gravel on the surface.
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11-03-2016, 12:03 PM | #84 |
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There is no way for the shields to move, be installed wrong, or bend on their own.
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11-04-2016, 01:51 PM | #85 |
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Not sure this accumulation of experiences is getting us anywhere, but for me 11 times in 1400 miles. Ten of those times occurred while going quite slowly, twice while making a slow turn. I wonder if this is only happening while going slowly or that that is the only time we can hear it (engine noise at higher speeds).
I still haven't heard from anyone here that has had a dealer do anything other than the brake dust shield thing which I seriously doubt is the source of the problem. I never drive on gravel roads and it is very unlikely that on the paved roads I' travelling a stone is thrown up into the brakes that often, at such slow speeds, and makes that sort of noise. Also wonder if anyone has had success getting their dealer to speak with a BMW service rep about this. Mine won't. I don't think they believe me about the noise!!
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Last edited by andrettifan; 11-04-2016 at 01:51 PM.. Reason: typo |
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11-04-2016, 02:58 PM | #87 |
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No dips or rear suspension travel for me. Ten of eleven times I was slowing either to a stop or making a slow turn on level pavement. iI wasn't always on the brakes; some of the time I was literally coasting to a stop. The one time I heard it when I wasn't going slow was in a straight line in third gear accelerating (not aggressively).
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11-04-2016, 03:09 PM | #88 | |
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