Tha Original i30 Owners Club

GOT PROBLEMS OR ISSUES? => GENERAL => Topic started by: thekswenson on March 11, 2020, 09:53:54

Title: Clunk from rear (even AFTER stopping)
Post by: thekswenson on March 11, 2020, 09:53:54: 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:

:link: Clonking noise on uneven roads (https://i30ownersclub.com/forum/index.php?topic=7575.msg97365#msg97365)
:link: Clunking noise at the rear of my car (https://i30ownersclub.com/forum/index.php?topic=37291.msg380066#msg380066)

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.
Title: Re: Clunk from rear (even AFTER stopping)
Post by: Surferdude on March 11, 2020, 10:15:09: 2009 model.
How many Klms?
Title: Re: Clunk from rear (even AFTER stopping)
Post by: thekswenson on March 11, 2020, 10:22:54: 150,000 km
Title: Re: Clunk from rear (even AFTER stopping)
Post by: Surferdude on March 11, 2020, 10:49:28: That's not a lot.
Is it possible a brake caliper is loose?
Title: Re: Clunk from rear (even AFTER stopping)
Post by: CraigB on March 11, 2020, 11:30:02: or one of the exhaust hangers :undecided:
Title: Re: Clunk from rear (even AFTER stopping)
Post by: thekswenson on March 16, 2020, 22:33:41: It has now happened twice about 4 seconds after coming to a complete stop!
The exhaust system seems to not be moving much.
Title: Re: Clunk from rear (even AFTER stopping)
Post by: Surferdude on March 16, 2020, 23:27:55: I still wonder if you've got a sticky brake caliper.
Title: Re: Clunk from rear (even AFTER stopping)
Post by: thekswenson on March 17, 2020, 19:46:01: 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?
Title: Re: Clunk from rear (even AFTER stopping)
Post by: Surferdude on March 18, 2020, 02:49:31: Quote from: thekswenson on March 17, 2020, 19:46:01
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.
Title: Re: Clunk from rear (even AFTER stopping)
Post by: thekswenson on March 18, 2020, 16:04:17: 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.
Title: Re: Clunk from rear (even AFTER stopping)
Post by: Surferdude on March 18, 2020, 18:19:54: 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.