Clunking sound in passenger rear tire area

Has anyone experienced a "clunking" sound over bigger bumps (like separation joint between bridge/road). The clunk sounds like metal-on-metal, similar to having a bunch of tools in a box that quickly rattles and then stops.

Trunk is empty, spare tire is secured, pulled out the jack and stuff with no change in the sound. Checked the convertible frame under the boot and everything is rock solid.

Sound doesnt happen on every bump, just those heavy-bumps that get your attention.

Any ideas or hints?

Thx for the help!

I've read it could be the differential mount. I have the same issue in my 01 325Ci vert. I'll ask my mechanic next week to check it. I'll let you know.

Originally Posted by 2001greenvert

I've read it could be the differential mount. I have the same issue in my 01 325Ci vert. I'll ask my mechanic next week to check it. I'll let you know.

Sounds good. Please let me know what he says. Only appears to be on the passenger side but I suspect replacing both is the best decision.

I would check your rear shock mounts to be sure the rubber hasn't pushed thru the mount or is just worn out and the top of the shock is just banging around in the mount when you go over a bump. Check both sides. see photo's...

1. Removed the 2 access hole covers.

2. Look in between the 2 shock mount nuts to view the rubber bushing and the top of the shock strut.... push up and down on the car to make sure the rubber is not loose in it's mount allowing the top of the shock to hit the metal above it.

I had a broken rear spring replaced both now nice and quiet. Don't know if this is common? this is on a 2003 325ci convertible

Ron W
Saint Paul, MN

Originally Posted by wolffy

I had a broken rear spring replaced both now nice and quiet. Don't know if this is common? this is on a 2003 325ci convertible

Ron W
Saint Paul, MN

Did you hear the spring on every bump? Or just the bigger ones?

To me, my rattle sounds like metal-on-metal and not a "thump" when I hit bigger bumps. Almost sounds like a bunch of tools rattling together. I'm guessing it may be a broken spring now bc of the sound. Will have to check it out at lunch time.Weird in that it doesn't always make the sound, only on certain bumps.

Metal on metal...hmmm could be end links. Very common in the front though, I haven't experienced this noise in the rear.

Rear springs do break, its not uncommon in certain rust prone geographical areas.

Its really easy to pull out the rear spring to inspect.

Loosen lugs

Jack car up/Secure with jackstand.

Pull wheel off

Use your OEM jack, secure, and wedge it in on the RTA, start jacking it (lol) to help you release tension. "This will push down on trailing arm where otherwise, a helper would be required.
Wiggle the spring as you do this, so you know when you have it loose.

Once tension is relieved:

Observe everything make mental note for reassembly, and pull the spring out.

The plastic mounting pads will likely come out with it. Observe which is top and which is bottom.

Keep the jack wedged in there to allow easy reinstallation.

Best of luck.

Originally Posted by petemo94

Did you hear the spring on every bump? Or just the bigger ones?

I only heard the noise on larger bumps I did notice the car didnt quite site level also. car has 120k miles on it.

I am trying to figure out the same issue. My car is sitting lower on the passanger side. I have been hearing that noise coming from the back on the same side. I installed new springs (H&R) and Koni yellows and the situation got worse since the new springs make the car a little bit lower.

Another thing I notice is the convertible top tray is not sitting perfectly flush on the passanger side, as it does on the driver's side.

I am praying that its not a subframe issue (Verts are less prone).
Could it be an old RTAB that is causing this? Maybe a Rear Shock Mount?

Car has currently 74K miles.

Originally Posted by tinchomermoz

I am trying to figure out the same issue. My car is sitting lower on the passanger side. I have been hearing that noise coming from the back on the same side. I installed new springs (H&R) and Koni yellows and the situation got worse since the new springs make the car a little bit lower.

Another thing I notice is the convertible top tray is not sitting perfectly flush on the passanger side, as it does on the driver's side.

I am praying that its not a subframe issue (Verts are less prone).
Could it be an old RTAB that is causing this? Maybe a Rear Shock Mount?

Car has currently 74K miles.

Funny you say passenger side sits lower than driver side. I took a measurement of my 2 rear wheel arches. The passenger side was 1/2-inch lower than driver side. Checked the rear suspension and springs. All looked solid - no issues found.

My sound definitely occurs on the passenger side. But now I'm suspecting its not coming from outside but somewhere inside, as you hit a decent size bump. Still baffling to me, but will check inside the rear-passenger side seat area (arm rest, under seat, near convertible top,...).

Will report when I find the cause.

I figured it out! One of the bolts on the RSM (rear shock mount) on the passenger side was loose... What happened was, I installed new H&R sports springs and Koni yellows a week ago and I guess..somebody forgot to re-tight everything...

Originally Posted by petemo94

But now I'm suspecting its not coming from outside but somewhere inside, as you hit a decent size bump. Still baffling to me, but will check inside the rear-passenger side seat area (arm rest, under seat, near convertible top,...).

Will report when I find the cause.

Nothing looks out of place from the rear suspension point of view. No cracked spring (I've got an 04-325CiC so those spring issues have been addressed since 2003).

Appears to happen more with the top up .vs. down. Looked inside the passenger side lift mechanism and everything is tight. Suspecting it may be how its sitting on the hard cover. Still investigating and quite baffled at the moment. Nothing obvious stands out.

Originally Posted by petemo94

Has anyone experienced a "clunking" sound over bigger bumps (like separation joint between bridge/road). The clunk sounds like metal-on-metal, similar to having a bunch of tools in a box that quickly rattles and then stops.

Trunk is empty, spare tire is secured, pulled out the jack and stuff with no change in the sound. Checked the convertible frame under the boot and everything is rock solid.

Sound doesnt happen on every bump, just those heavy-bumps that get your attention.

Any ideas or hints?

Thx for the help!

Must be the differential mount! BMW had a recall on those! It is quite serious problem and expensive to fix! Not a good news!

Originally Posted by plachkoff

Must be the differential mount! BMW had a recall on those! It is quite serious problem and expensive to fix! Not a good news!

Was driving around today. With the top down, I dont hear the problem. With the top up, it sounds likes metal tools rattling around in the back seat. Really weird, but I suspect its not suspension related anymore. Thinking now it may be within the back seat or back passenger window area. Still havent figured it out yet.

Hmm.. have you checked that the large "concave" washer (acts as the stop for the bump stop) on the rear shock shaft just below the top mount isn't hitting the metal part of the mount.... when the rubber in the upper mount starts to age it will allow that washer to bang into the lower metal part of the mount. That washer also limits the shock shaft from punching way up into the top area of the car in case the rubber completely fails. Have someone rock the car up and down and look over the top of the rear wheel to check that washer isn't hitting the mount....just an idea.

Well I found the source of the noise. While I was working on my CCV, ICV and other stuff, I pulled the battery terminal. While I was in there, I must have banged it and it made the SAME sound as what I've been hearing.

I have an Interstate battery installed from the PO but I'm not sure it totally secured to the trunk like it should. Appears the convertible uses the battery to squelch certain frequencies to make the car sound/behave better.

So if you hear the clanking/clunking coming from the trunk, take a moment and move your battery and see if it rattles in place. Mine did (but I havent had time to properly fix it bc the CCV required nearly 2 full days of my effort to replace).

Thx for all of the tips during this investigation.

Originally Posted by petemo94

Well I found the source of the noise. While I was working on my CCV, ICV and other stuff, I pulled the battery terminal. While I was in there, I must have banged it and it made the SAME sound as what I've been hearing.

I have an Interstate battery installed from the PO but I'm not sure it totally secured to the trunk like it should. Appears the convertible uses the battery to squelch certain frequencies to make the car sound/behave better.

So if you hear the clanking/clunking coming from the trunk, take a moment and move your battery and see if it rattles in place. Mine did (but I havent had time to properly fix it bc the CCV required nearly 2 full days of my effort to replace).

Thx for all of the tips during this investigation.

That's great news. Its always comforting when you solve a problem that doesn't involve a mechanic and $2000 of your own money

Originally Posted by petemo94

Did you hear the spring on every bump? Or just the bigger ones?

To me, my rattle sounds like metal-on-metal and not a "thump" when I hit bigger bumps. Almost sounds like a bunch of tools rattling together. I'm guessing it may be a broken spring now bc of the sound. Will have to check it out at lunch time.Weird in that it doesn't always make the sound, only on certain bumps.

I have the exact same issue and cannot find it either. Only on larger bumps do I hear the metal-on-metal rattling sound.

Checked RSMs, battery, convertible top, subframe, ... stumped. Checking the CSB and diff bolts next.

Is the battery an after-market? Is it securely in place?

Try this, pick up one edge of the battery (1/2 inch?) and let it go. Does the sound resemble what you hear? This is the exact sound from mine.

I'll spend time this weekend trying to secure it properly. Not sure if its tied-down or not, didnt have time to be absolutely sure with it.

Also, I learned the battery in the "vert" is used not only for an electrical source, but also a dampening source to help certain vibrations be reduced (or eliminated). Pretty wild to think they went thru this effort to reduce harmonics and vibrations by placement and configuration of the battery.

Report back what you find.

I mentioned checking the battery, its OEM and securely fastened. I wish it was that simple.