scraping noise whenever change in momentum/direction happens

mikoz · 01-12-2017, 06:13 PM

Hi all,

I have a 2010 M3 sedan with 31k miles. Brake pads are good and car has had an easy life.

All of a sudden, the car makes a scraping sound whenever the body is presented with a change in momentum (e.g. braking, cornering) even at very low speeds. It sounds like 2 pieces of coarse metal scraping together. When it happens it's not periodic nor does it even seem to be related in intensity or sound to the speed of the car. I don't think it's the brake pads, as there's plenty of pad life left and the noise happens even while not pressing the brake pedal (although doing so obviously excites a change in momentum). The noise does not happen in Park while modulating the throttle, so I don't think it's engine related (I was concerned about rod bearing issues, but I don't think that's happening here). However, if it's starved for oil or something, I guess that's a possibility, but we are talking about 5mph here, it's not really stressing much.

The noise is more pronounced while the car is cold but can still happen even once it's warm. I am not certain that's a definite truth, though, I don't yet have enough info to say for sure.

it also doesn't always happen, even when driving the same way at the same speed on the same road that caused the noise to appear just a minute earlier.

It's very hard to pinpoint because I have to be in the car obviously to hear it and at higher speeds it's muted by the engine and tire noise. I can't pinpoint front or rear or left/right, either.

All fluids look ok.

Could this be a suspension or bearing or diff issue possibly? I am guessing it's a bearing of some sort.

I have EasyCare still, so if it's something major I'm not going to get too upset

G-Lo408 · 01-14-2017, 02:14 AM

Have same issue but I did change my diff fluid and didn't use the FM booster one cause I wanted the diff to lock better. It's the diff but if you still have the easycare then take it in and have them check it out

Pig Farmer · 01-14-2017, 06:59 AM

I had a similar experience a few months ago. The sound was definately metal-on-metal and it was coming from the rear wheel well. I found a thread on this forum that used the term "cow bell" to describe the noise. There were two theories for the noise. One suggested it was a stone caught between the rotor and brake shield. While possible, I pulled the wheel and found nothing. The other theory was that the rear parking brake assembly/pad shifts and somehow begins to catch on the brake shield. This seemed strange to me since the brake shield does not rotate/move. However, the thread suggested that you pull the parking brake a few time while rolling which re-aligns the parking break assembly. This worked for me. If you need a better description, do a search for "cow bell" in the title of the thread.

mikoz · 01-14-2017, 10:20 AM

I had actually suspected the p brake too, and tried to do a few quick pulls at speed but it doesn't seem to change it.

I checked the rotors and everything looks ok there.

It could be the parking brake or the diff or a bearing of some sort.

I'll take it on Monday.

Thanks.

01-12-2017, 06:13 PM	#1
mikoz New Member 2 Rep 11 Posts Drives: 2010 BMW M3 Sedan Join Date: Mar 2016 Location: Austin, TX iTrader: (0)	scraping noise whenever change in momentum/direction happens Hi all, I have a 2010 M3 sedan with 31k miles. Brake pads are good and car has had an easy life. All of a sudden, the car makes a scraping sound whenever the body is presented with a change in momentum (e.g. braking, cornering) even at very low speeds. It sounds like 2 pieces of coarse metal scraping together. When it happens it's not periodic nor does it even seem to be related in intensity or sound to the speed of the car. I don't think it's the brake pads, as there's plenty of pad life left and the noise happens even while not pressing the brake pedal (although doing so obviously excites a change in momentum). The noise does not happen in Park while modulating the throttle, so I don't think it's engine related (I was concerned about rod bearing issues, but I don't think that's happening here). However, if it's starved for oil or something, I guess that's a possibility, but we are talking about 5mph here, it's not really stressing much. The noise is more pronounced while the car is cold but can still happen even once it's warm. I am not certain that's a definite truth, though, I don't yet have enough info to say for sure. it also doesn't always happen, even when driving the same way at the same speed on the same road that caused the noise to appear just a minute earlier. It's very hard to pinpoint because I have to be in the car obviously to hear it and at higher speeds it's muted by the engine and tire noise. I can't pinpoint front or rear or left/right, either. All fluids look ok. Could this be a suspension or bearing or diff issue possibly? I am guessing it's a bearing of some sort. I have EasyCare still, so if it's something major I'm not going to get too upset
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01-14-2017, 02:14 AM	#2
G-Lo408 El Eme Tres! 25 Rep 287 Posts Drives: 08 E92 M3 Join Date: Jul 2011 Location: San Jose, CA iTrader: (1)	Have same issue but I did change my diff fluid and didn't use the FM booster one cause I wanted the diff to lock better. It's the diff but if you still have the easycare then take it in and have them check it out __________________ Zero Ocho BMW Eme Tres
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01-14-2017, 06:59 AM	#3
Pig Farmer Major 340 Rep 1,293 Posts Drives: E92M Join Date: May 2010 Location: Florida iTrader: (0)	I had a similar experience a few months ago. The sound was definately metal-on-metal and it was coming from the rear wheel well. I found a thread on this forum that used the term "cow bell" to describe the noise. There were two theories for the noise. One suggested it was a stone caught between the rotor and brake shield. While possible, I pulled the wheel and found nothing. The other theory was that the rear parking brake assembly/pad shifts and somehow begins to catch on the brake shield. This seemed strange to me since the brake shield does not rotate/move. However, the thread suggested that you pull the parking brake a few time while rolling which re-aligns the parking break assembly. This worked for me. If you need a better description, do a search for "cow bell" in the title of the thread.
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01-14-2017, 10:20 AM	#4
mikoz New Member 2 Rep 11 Posts Drives: 2010 BMW M3 Sedan Join Date: Mar 2016 Location: Austin, TX iTrader: (0)	I had actually suspected the p brake too, and tried to do a few quick pulls at speed but it doesn't seem to change it. I checked the rotors and everything looks ok there. It could be the parking brake or the diff or a bearing of some sort. I'll take it on Monday. Thanks.
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