Clunk in rear of car...

[mazda747]

Hey guys, I'm new here. I just bought a 2010 Mazda 5 Sport 5sp. When I go over speedbumps (no matter how fast or slow), the back end of the car sounds weird, like a clunk when coming off the bump. At first I thought maybe it was the tire tray in the back, but it sounds more like its coming from the shocks and I'm not going fast enough to make the tray jump up out of its spot.

I'm just wondering if anyone else has had this issue or heard of this issue. The car has 450 miles on it so could it just be it needs to be "broken in"?

Thanks!

Tim

 

[SuperJETT]

450 miles, take it to the dealer.

 

[flcruising]

Not normal.

 

[mazda747]

Ok, I'll do that. It should sound like the front, correct? Just nice and smooth?

 

[Martyd]

2010 Sport. No clunk here as well.

 

[flcruising]

Should be clunkless.
What exactly does 'nice and smooth' sound like?

 

[mazda747]

It's hard to describe the sound but you can definitely tell a difference in sound from the front compression of the shocks and the rear. Almost like the rear shocks are bottoming out or something. Should the rear sound like the front when going over a speedbump slow? I assume yes which is why I think I might have an issue. Almost like there is something loose or something.

 

[Rockin03mp5]

you sure there isnt something rattling around in the spare tire compartment?

 

[flcruising]

Good point.
Maybe someone left a soda can back there. <- I've heard stories like that, with hard to diagnose symptoms. Then a 'lightbulb' moment!

 

[mazda747]

I did check but tonight I'm going to pull the tray out with the tire stuff in it just to make sure. It does feel like its coming from under the car though, but we'll see. I scheduled service for Thursday and will cancel if it goes away after removing the spare tire stuff.

Thanks again!

Tim

 

[Silentnoise713]

Did you buy the car new or slightly used (with 450 miles on it)? Did you buy from a dealership or mom and pop shop?

If new, did you just notice this now or did something happen that lead to this (big pothole/curb)?

Unless there is some shady history with the car (could be a lemon or the assembly worker was cranky the day he/she was assembling your car), I would guess something is loose.

 

[mapguy]

Could it be the Rear Coil Spring perch thing? I read on the forum about a fix where a weld needs to be ground down on one of the spring seats.

 

[mapguy]

I should add that I heard a "pop" the other day making a left hand turn that sounded like a kid threw a rock at the car. It came from the back. I hope it's not the same thing. My 5 only has 150 miles on it. I chalked it up to my mag lite sliding around in the storage area above the spare, but will definitely keep my ears open.

 

[mazda747]

I bought the car new with 30 miles on it for a Mazda dealer. It's done this since the day I brought it home because I have to go over a road with speed bumps to get to my house and noticed it the first night. I looked in the back last night and there is nothing loose back there that would be making the sound. I have an appointment tomorrow morning at the dealer to have them check it out. I'm driving it to Florida in 2 weeks so I want to make sure everything is as it should be back there before the 900 mile drive.

Mapguy, did you read that on this forum or another one?

Thanks.

Tim

 

[mazda747]

I should add that I heard a "pop" the other day making a left hand turn that sounded like a kid threw a rock at the car. It came from the back. I hope it's not the same thing. My 5 only has 150 miles on it. I chalked it up to my mag lite sliding around in the storage area above the spare, but will definitely keep my ears open.

It's not a pop sound that I'm hearing. It's almost like a shock without fluid in it.

Could yours have been a pebble in the wheel that hit the wheel well as you made the turn and put side pressure on the wheel?

 

[mazda747]

So I got the car back from the dealer. They heard the noise I was talking about and tightened everything down in the rear. The car still makes the noise and I test drove another one at the dealer and it seems to make the same noise. Although I didn't have a speedbump to go over, just a couple regular ruts. Guess I'll live with it...

 

[flcruising]

I guess I'll have to pay more attention to the rear as we drive over speed bumps (very rarely).

 

[wedginator]

My 5 has a clunk and it's not due to anything loose. Rather than bringing it back to the dealership, I decided to investigate this myself. I suspected it was coming from the shock because of the noise it made and the frequency of it. I took the shock off and drove without it around the block just so I can single out the noise. It was coming from the shock... More specifically it was the way the shock is mounted.

If anyone has taken the shock off their car, you'll see the shock mount has a rubber centre and the strut sticks up a few cm's. If the factory has mounted this a few mm's offset, the strut sticking up has a chance of hitting the chassis when going over bumps because the rubber flexes. I un-did the mount, and luckily I placed it where it would not clunk anymore. I spent months trying to figure out this problem... So glad the noise is gone...

 

[flcruising]

Do you have a picture to show what you describe?

 

[wedginator]

Do you have a picture to show what you describe?

Not my picture, but from another thread... this is the parts I'm talking about: The little thing that protrudes out (the nut as well) can rattle against the chassis due to the rubber flexing.