»Strange metallic "clunk"

Give us even the vaguest hint as to what car...?

Side issue - but you'll also be much more highly regarded, and more likely to get help, around usenet groups if you figure out how to post to usenet, instead of to some crappy web forum that freeloads off usenet.

I couldn't have put it better myself.

But that notwithstanding, it might be a parking brake shoe finally releasing. If the car has drum brakes, of course. Who knows?

Thank you - and yes, should have said Ford Focus, 2009

It's the ABS selftest. Perfectly normal.

Thank you so much, that's stopped me worrying.

I've driven many vehicles with anti lock brakes and I've never heard any noises until the moment the modulator kicks in during a stop with reduced grip. Drive well within the limit of the grip available and the noise never appears.

What precisely is this ABS selftest doing and why is this so badly implemented there is a metallic clunk during normal operation?

A quick Search for "abs brakes self-test" turned up this:

I've also driven plenty, and it's only my focus that makes the noise. No idea why its so loud, but it is normal.

Is that other Ford Focus don't make the noise? Or Other Fords don't make the noise? Or Other makes of car with other makes of ABS don't make a noise?

My 80's Nissan makes a whir as the motor runs up to prime the accumulators once it exceeds 19mph. At which point it would throw a warning if that failed. Other basic checks like solenoid continuity and sensor integrity are done at switch on.