Hi everyone,

I started having a very annoying issue where I cannot drive my car due to the fact that I am scared if smth is really wrong underneath the car..
Problem is that when I brake - there is a clunking sound coming from what I believe - the back of the car. The sound I hear only when I am driving slowly, for example near to a stop in the car parking lot. When braking while going 60-80 - I can't hear it, but most likely due to all the other surrounding noise. Interesting thing is the sound is getting bigger when you drive the car more. For example after the night I can drive 2-5 kilometers with no issues and no sounds, afterwards I start to hear mild clunking sound and if I drive more, for ex. 20 mins - it starts to clunk really really bad that I can feel it. So why does it come gradually? Is the temperature is at play here?

This all started after rear brakes were replaced..both disks and pads. I have sent the car back to the shop where they replaced it - they could not find anything wrong with it, took it to another shop - same thing, they re assembled the rear brakes - nothing bad with them. Shop also found that sway bar stabilizers(bushings) where shot - so replaced them, but the problem did not go away.. They have also found that differential's bushings were also bad - they will replace them next week.
They said that suspension should not be the cause here as it is still in good condition otherwise.. Regarding the differential..I think if bushings were bad - I should hear it when I accelerate or like, always, not gradually increasing in sound.

I'm lost here, any ideas?

Video of the sound in question: https://www.youtube.com/watch?v=4VHj...ature=youtu.be

 

Most likely loose brake pads or sticky guide pins for the pads. My GS did it up front for a while, but when I removed the pads, took a wire brush to the rust on the pins, then put on a light coating of anti-seize, they freed right up and haven't done it since. If the shop didn't properly reinstall the brake pad retaining clips, or install them at all, then they could be shifting around, causing there to be a gap between the pads and pistons; if this is the case, there will be a clicking noise when braking, since the piston and pad are connecting.

 

They have cleaned the pins as they were rusty, had them lubricated. I suppose second shop would have noticed that any brake hardware is missing, like clips. Is there a way to check if they are installed without removing the assembly/wheel? I've tried to move the pad with hands without disassembling anything - they are pretty firm.

 

Sorry, didn't see the video. Definitely doesn't sound like loose brake pads, but can't rule it out completely. Can you get a video from the outside, close to each wheel while applying the brakes? Also, are the pads and rotors OEM or aftermarket? Do you notice any wobbling when you brake from a roll? I was going to suggest bushings, but it sounds like you have that covered. Do your calipers wiggle a bit when you grab and shake them?

 

Kinda hard to tell from the video, but why werent the mechanics able to pin point the problem? I mean the sound is pretty obvious! Is it possible for you to crawl under the car and tape your phone or a gopro pointing to the inside of the wheels suspension?

Sounds almost like a bad wheel bearing, when you hear the sound does turning the steering wheel change the pitch of it? What about when applying the brakes does the knocking change its pitch?

 

@TRD_Power From outside it's almost silent, no sound. Pads and rotors are aftermarket, when I brake I have no wobbling. I have taken another used brake caliper and swapped it in - same movement as with mine - so discarded that as well..
Will change the bushings for the differential - I hope it fixes it..

 

@ibidu1 They are looking into it but cannot find anything..They are saying that the suspension is solid except differential mounts which they will replace next week.
If if turn the steering wheel it does not make any difference. The clunk sounds starts when I apply brakes only. To be exact I hear the sound when I am driving slow and about to park the car - as soon as I hit the brakes - the clunk comes in. BUT - the clunk does not come in if I brake in reverse, only in D.

 

Ok, I am thinking maybe its the parking brake pads that are inside the center of the brake rotors. More likely the second mechanic only looked at the caliper and didnt remove the rear rotors. You have to remove the rear rotors to inspect the parking brake pads, to make sure they are properly in place and not just hanging loose or maybe its not properly tensioned.

Try this! Drive and when the car does its clunking, press on the emergency brake and see if the noise changes. If it changes then that your issue.

This is what the rear parking brake looks like, in the video its an IS but it should be the same as a GS

 

@ibidu1 I've tried what you have suggested, when I press the emergency brakes I hear no sound of clunk. First time I've pressed the emergency brake seemed like pads were sticky a bit, most likely as I've never used that emergency brake. After driving a bit and pressing the emergency brake - it came back to OK.. Although I believe the emergency brake pads would need a replacement, seems to me they are worn out a bit if looking at the affectiveness of their work.

 

Awesome glad you figured it out, more likely the tolerance in the aftermarket rotors are bigger then the oem. So when the new rotors were installed the mechanic didnt properly adjust the brake shims or unhooked it by accident. Probably best you go back to the first mechanic and explain to him where the noise is coming from, it is his error.

 

@ibidu1 Wait, so if I brake normally, without the emergency brake and it clunks but if I only use emergency brake to stop and it does not clunk - that means it's the emergency brake assembly that is faulty?

 

Yes! If the parking brake shims are not seated properly they will flop around and slap the inside of the rotors, when you pressed the emergency brake that puts tension on the pads to press against the rotors therefor stopping the slapping/loosens. I wouldnt say its faulty unless you open it up and see, could just need to properly be adjusted, and that could simply be turning the nut for extra tension. Or maybe one of the internal springs fell off. But if you see the video I posted earlier you will see what is involved

 

@ibido1 Thanks for explaining, it does make sense. I will try to check that. Do you think it is dangerous to drive with the current condition? I will go to the shop maybe tuesday/wednesday, but till that time would need to get groceries and etc.

 

I wouldnt drive to far with it, the pads can snap and break a bunch of things. When you go to the mechanic explain the noise and tell him you think its coming from the emergency brake pad. Explain to him that there might be play in the adjustment, inspect and tighten them.