use a mini-microphone, + I-phone or Android phone, to locate the rattle?
 

Here's what I would try (loving gadgets): I'd buy one or more (in case one is lost or damaged) mini-microphones that I could hear/record sounds from inside or outside the X, and locate the rattle that way.

If the rattle is probably inside the X, then a corded mic attached to your phone could be used, or a Bluetooth mic could be firmly clipped onto, or taped (w/Gorilla tape) in place temporarily, near suspected sound sources undercar, for a short hop, and it would pick up the rattle, while driving.

Drive the same course, at the same speed, and move the mic from one location to another, until you can pinpoint the source of the sound.

On Amazon, a pair of wireless mics runs under $20 (a throwaway sum for X5 owners) and a corded one for less than that.

Just an idea.

Combine with FFT app


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