For a little while now (~ a month), the 380 front brakes that I've got on my TL have been rattling quite badly. I've taken the things apart about half a dozen times now, and I can't seem to be able to get them to quiet down. They only rattle when I'm on a bad road, which is most of Sydney. It stops, however, when I put my foot on the brake. I've been able to narrow it down to the caliper not being completely compressed when it's at rest (by that, I mean I can slide the caliper along it's guide pins a few mm).

My question for the experts: Does this mean that I'm mucking up the bleeding, or could it be a symptom of something more serious? The brakes have been on the car for about 30,000km now, and they were brand new when I installed them.

Got the anti rattle shims in there?

Got the anti rattle shims in there?

Yep, both the shims and pad clips. I've even tried some of that anti squeal paste to try and glue the pads in place, but that only lasted a few days.

Can you please explain this a bit more precisely for an old bugger like me......I understand the pistons are retracting into the caliper bore allowing the caliper to move along the slides?...is this correct?....if so you should have a very low pedal as when you apply the brakes this gap must first be taken up before the pads contact the disc, yet you do not say this. If the discs were distorted they would force the pad and piston back into the caliper but you normally do not hear a rattle. The only other way I could figure that the pistons get retracted is if the master cylinder has one of it's valves blocked meaning that when you take your foot off the brake pedal there is negative pressure in the hydraulic system.
My understanding of brakes is that the caliper should not move at all except to centalise the pads as they wear and when the brakes are applied to allow equal pressure on each pad. I've heard of caliper slides rusting up and becoming solid but never the way you describe it.
Just my opinion, but I'd be quite worried (as you are) if the caliper behaves in the manner you describe.

After a couple of hours of completely stripping both calipers, recutting every thread, cleaning out all the old grease and dust, and pressure washing everything, the noise seems to be cured. There was quite a bit of muck built up around the guide pin sleeves on the right caliper, which was the noisier of the two. I think this might've been the cause; the top pin was quite hard to move. Either way, it's all loctited back together and torqued to spec. Fingers crossed.

hako - that's pretty much what it felt like. The pedal height was normal, and the discs were machined about a year ago. was The master cylinder checked out fine though, so I'm hoping that I've solved it.