Strange metallic whistling noise coming from the rear.

[AC98]

Good morning everyone, and thank you in advance for your interest.

I own a 2011 BMW Z4 sDrive23i E89. While driving, I hear a kind of metallic whistling noise, similar to the sound of a train passing on the tracks.

I had the car checked by a mechanic, and he told me that there are no mechanical issues.

What could it be? Could it be related to the seals or weatherstripping?

Thank you very much for your help.

 

[B21]

Wheel bearing?

 

[AC98]

Already checked, there are no problems.

 

[NS66]

I am sure mine does similar - but can only hear when roof down and all windows down, does sound like a metallic grinding like pads make against the disc - I did wonder if was one of the backing plates slightly bent and catching perhaps?

 

[AC98]

Exactly, that’s the kind of noise I mean. Do you happen to know what caused it?

 

[MikeyH]

Could there be a small stone stuck between the pad and the disc?

 

[AC98]

I don't think so. The car was put on a lift and checked by the mechanic.

 

[therealmc]

I get a similar noise too, either intermittently or just not always heard.

 

[Miscowjones]

Beginning of a failing wheel bearing?

 

[Miscowjones]

OP not been on since posting, wonder what it was. I think @NS66 has nailed it with the backing plates, particularly if they are crumbly.

 

[NS66]

OP not been on since posting, wonder what it was. I think @NS66 has nailed it with the backing plates, particularly if they are crumbly.

Ive since checked mine - jacked each wheel and spun - no noise or play at all so dont think its the plate, wheel bearing or sticking pad.
Very strange
I am wondering could it be just wind noise? I have the 19" 326M Double Spoke - only hear it over 30. Will be trying some 18" wheels as a comparison soon so will report back.

 

[B21]

326m wheels as such don’t make noise..tyres?