[Impious]

A couple weeks ago, I noticed a strange rattling sound from the front left of my 330Xi (barely out of original warranty). It seems to happen when driving at low to medium speed over rutted or undulating roads. It also seems to happen when coming to a full stop, or even gently accelerating while turning. It sounds like something in the suspension is loose. It's causing me to be concerned about the road-worthiness of the vehicle.

The sound itself is hard to describe, but sounds somewhere between a pop and rattle, like when a subwoofer bottoms out. It happens repeatedly as the suspension is loaded and unloaded, and as far as I can tell, the ride has not perceptibly changed.

I took it to the stealership once, and they said it was my plastic splashguard which was broken, and fluttering. Had them replace it. Apparently I bottomed the car out in one of the nastier potholes left by our wetter than usual winter. Anyhow.. no dice... still happens, and seems to be getting worse.

Took it to the stealership again, who sat on it for two days, and now claim it's "loose aftermarket brake pads" A claim which I find to be pretty dubious. None-the-less... I went into the service bay with the foreman, with the car in the air. I watched and listened as he beat on the tire with a mallet, reproducing the sound.

Then he instructed the tech to remove the wheel, remove the caliper, and bolt the wheel back on. The tech held the caliper, while the foreman beat on the wheel again... no sound, eureka! right? So now they want to replace the brake pads, which have about 80% left on them. I didn't have it done cus I was already late for work, so I scheduled a third appointment.

Driving home, I hit several spots in the road that I knew reproduced the issue, so I decided to gently apply the brakes... and wtf... It still made the same sound with my foot on the brake. I did this several times, and it always had the same result.

First thing when I got home, I jammed a screw driver in the gap between my caliper and brake pad. ok... so there's a liiiiitle room for it to wiggle, but not much, and it took some effort. so I grabbed a washer, filed down the edge a little and jammed it in the gap. Beat on it a bit with a hammer until it was nice and wedged. Now any rotational play from the outside brake pad is eliminated. Took a quick test drive... no change... it still made the sound.

So at this point... the only way it's possible that this is due to a loose "undersized" brake pad is that the inner pad is serrriously floppy, and somehow magically still flopping around under braking. I call BS.

Could it be something wrong with the caliper itself?
Either way, South County BMW has fantastic customer service, but otherwise my experience with them has left me a bit underwhelmed over the past few years.

Cheers