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      12-14-2022, 08:06 PM   #1
One128i
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Rear clunk over bumps

I have a 2012 128i coupe. I've had this rear clunking noise over small bumps or manholes from the drivers rear side. Strangely, this happened right after I swapped to my winter tires and rims.

I emptied the trunk and the noise is still present. New rear shocks (Bilsteins) were installed by a Euro shop in August - they checked over everything last week and the rear end is tight.

I did a search and read some threads. I thought the issue was the sunroof cover (when open), but as of today the noise is present regardless of sunroof cover (although the clunk is more muted when closed).

Its driving me nuts. What else could it be? Is there something loose in my headliner? How do I check that?
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      12-14-2022, 09:03 PM   #2
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That set of tires been on before? Are they hitting the suspension?
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      12-15-2022, 05:34 PM   #3
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They're the same set of tires and wheels for 5 years now.
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      12-16-2022, 09:31 AM   #4
JohnRa
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I had that and it turned out to be the upper strut bushings on the rear shocks, though I imagine the shop that put in your Bilsteins probably replaced them. Maybe worth a look though.
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      12-16-2022, 09:48 AM   #5
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Quote:
Originally Posted by JohnRa View Post
I had that and it turned out to be the upper strut bushings on the rear shocks, though I imagine the shop that put in your Bilsteins probably replaced them. Maybe worth a look though.
That or the strut itself are where I would look as well. When I've had these noises over the cars I've had in my lifetime it's been a dead strut.

I do get that it happened with the wheel / tire change and so it makes a lot of sense as well...

You kind of have to have a feel for noises, take your best guess at what might be hitting or bouncing around. Can you find someone to sit in say the driver's side back seat, with the passenger side folded down, and see if they can get an idea?
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      12-19-2022, 11:42 AM   #6
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From inside the trunk, remove the semi ridgid piece which gives access to the top of the shock absorber. It measures 12"x6". Fold down rear seats, then get yourself into the trunk and have someone drive the car over roads where your hear the noise. If it is he shock absorber, you should easily be able verify. Maybe take a short video.
Now if this 12x6 piece doesn't work, remove the whole semi ridgid piece about 34"x17".
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      12-19-2022, 07:34 PM   #7
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Mounts were new along with the shocks.

Quote:
Originally Posted by tracer bullet View Post
That or the strut itself are where I would look as well. When I've had these noises over the cars I've had in my lifetime it's been a dead strut.

I do get that it happened with the wheel / tire change and so it makes a lot of sense as well...

You kind of have to have a feel for noises, take your best guess at what might be hitting or bouncing around. Can you find someone to sit in say the driver's side back seat, with the passenger side folded down, and see if they can get an idea?
What do you mean by the tire change? The shock could've failed right after the tire change (coincidently or causation)? I noticed the noise on the drive home.

Quote:
Originally Posted by NorthernDancer View Post
From inside the trunk, remove the semi ridgid piece which gives access to the top of the shock absorber. It measures 12"x6". Fold down rear seats, then get yourself into the trunk and have someone drive the car over roads where your hear the noise. If it is he shock absorber, you should easily be able verify. Maybe take a short video.
Now if this 12x6 piece doesn't work, remove the whole semi ridgid piece about 34"x17".
I see there are two pieces - one is to access the taillight, and the other is near the seatback with 2 plastic screw popouts. The latter looks like the entire half trunk liner.

I'm getting new brakes installed at a different shop on Wednesday. Maybe I'll ask to do a check...
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      12-19-2022, 09:43 PM   #8
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Quote:
Originally Posted by One128i View Post
What do you mean by the tire change?
Just that you said that's when the noise started, after getting the winter tires on. logic would say it's related to the difference there - the winter tires. But of course that also doesn't make sense so... My point only being that focusing on what changed is a reasonable troubleshooting plan.

It could still be related. Maybe getting it up in the air, and the wheel hanging, somehow moved or loosened a part that caused it. or it could still be a bad mount or strut and getting the car in the air caused it.

Strut could be loose too, or the mount. Bolt(s) came loose perhaps.
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      12-21-2022, 09:44 AM   #9
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One other possibility, are the new mounts Oem? If I recall some people on the forum replaced the rear upper strut mounts with Monroe ones (as an upgrade; they are much harder than the soft, foam-ish material of the OEM's) and reported clunking noises that were solved by reverting to OEM.
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      12-23-2022, 12:22 PM   #10
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2 shops made sure everything was tight in the rear end.

I'm not sure if mounts are OEM, I don't think they are, but definitely OE.

Clunk is intermittent. More likely to make noise when warm vs. cold.

Sigh. I really wanna say its the shock itself but how would they diagnose that?
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      12-23-2022, 02:33 PM   #11
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Quote:
Originally Posted by One128i View Post
Sigh. I really wanna say its the shock itself but how would they diagnose that?
Have to see if it's got any pressure in it.

You could... take a guess by seeing if that corner of the car bounces more than the other side - pressing down on the trunk kind of thing. I never really found that to work though. You might be able to see something like oil from where the steel tube goes through the seal and into the shock body. Or undo the strut from the mount at the top and see if that tube drops down into the rest of the strut.

Best way is to get the shock completely off the car, you'll know quickly if it's blown and has no pressure.
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      12-24-2022, 08:35 PM   #12
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Do you have a rear sway bar? If so check the end links.

If not, I suspect a bad or incorrectly installed shock mount. Ppl mess the order/ placement of the washers all the time.

Stock is best, though I'm using KYB this go around and they're great. I'm on Bilstein coilovers with no noises.
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      12-25-2022, 09:46 AM   #13
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Quote:
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Do you have a rear sway bar? If so check the end links.
Yes! Excellent idea that was missed. Sometimes even just squeaking in the bushings can sound "clunky" because they are so tight.
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      12-25-2022, 11:44 AM   #14
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Thanks, the problem has been put on hold because of my brake issues 😥
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