[thekswenson]

Hello,

I'm experiencing a clunk from somewhere in the back half of the car. The clunk happens only rarely and is hard to reproduce.
THE CLUNK DOESN'T HAPPEN WHEN:
- accelerating hard
- breaking hard
- going over speed bumps

THE CLUNK HAPPENS WHEN:
- cruising casually on slightly uneven road
- lightly breaking when in traffic
- a second or two after coming to a full stop (!!!!!)

The last one really surprised me.  I found a couple posts summarizing typical problems:

Clonking noise on uneven roads
Clunking noise at the rear of my car


I checked that the rear suspension plastic covers are not coming loose. Could the "movement between the rear shock absorber damper rod cover and the upper strut mounting bush" be the culprit?

Any other ideas of what could be making this clunk?

Thanks for your ideas.

[Surferdude]

2009 model.
How many Klms?

[thekswenson]

150,000 km

[Surferdude]

That's not a lot.
Is it possible a brake caliper is loose?

[CraigB]

or one of the exhaust hangers

[thekswenson]

It has now happened twice about 4 seconds after coming to a complete stop!
The exhaust system seems to not be moving much.

[Surferdude]

I still wonder if you've got a sticky brake caliper.

[thekswenson]

About the caliper, could it make a clunk that I can (faintly) feel in the driver's seat?
Could you explain to me what the cause of the noise is, when there is a sticky caliper?

[Surferdude]

About the caliper, could it make a clunk that I can (faintly) feel in the driver's seat?
Could you explain to me what the cause of the noise is, when there is a sticky caliper?

Oh well. It's rare but I've seen it a couple of times.
Not on i30s but back when I was working.
There's a small amount of reflex built into brake piston seals (so the pads don't stay locked on the rotor when the brake pedal isn't applied) and if there's a bit of grit or gunk building up the piston can take a moment or two to retract, letting the calliper loose on the rotor. Because everything else is quiet, there's a slight clunk when this happens.

[thekswenson]

Thanks @Surferdude ...
  it sounds like the clunk would be pretty faint then, depending on how far the piston has to travel before clunking back onto the pad. I'm not sure I would feel this force.

I won't rule it out, however. Do you have any hints for checking if it is the piston?

I'm thinking of maybe attaching a gopro back there.

[Surferdude]

Only by an inspection around the calipers and seals. Make sure any dust covers are intact.
I'm not sure about the set up so that may be easy or hard.

But you're right. It wouldn't be very loud.