Can a worn strut make a clunk or popping sound?

I installed Dinan springs and their ride comfort kit on my 2009 M3 with 130k miles. The struts are original and don't rebound at all.

After the install (long story) I noticed a clunk from the passenger side near the firewall. It happened a couple times when I turned the wheel or went over a bump. I put the car in the air and found this. No noise on the driver's side.

I assumed it was a bad bearing. Dinan was gracious enough to send out a replacement top hat. I replaced the bearing but not the top hat itself. I torqued down the top nut with the assembly out of the car and noticed the strut was squeaking and creaking while the spring was fully extended and seated. It went away when I compressed the spring slightly. It was very clear that the noise came from within the strut body.

Without a replacement, I threw it on the car anyway. There's no creak (thank goodness) but I still have the same clunk. I re-checked the torque on the top nut with the car on the ground.

My question: is it possible for a strut to make a clunk in rotation like that? If so, I'll assume that's the issue. I need new ones anyway. If not, I'll keep searching.

The only other weird thing I noticed was that the stupid shaved top hats don't seem to be perfectly level on the bottom. I figured there's enough play in the rubber mount for this not to matter, but maybe there's a bind between the metal bushing and the metal cups? I regret not swapping to the new top hat now!

I'll put the car back up in the air to see if I can pinpoint the exact location of the noise. The only other thing that's moving when I move the spring like that is that end link, very slightly.

tjames975 wrote

I installed Dinan springs and their ride comfort kit on my 2009 M3 with 130k miles. The struts are original and don't rebound at all.

After the install (long story) I noticed a clunk from the passenger side near the firewall. It happened a couple times when I turned the wheel or went over a bump. I put the car in the air and found this. No noise on the driver's side.

I assumed it was a bad bearing. Dinan was gracious enough to send out a replacement top hat. I replaced the bearing but not the top hat itself. I torqued down the top nut with the assembly out of the car and noticed the strut was squeaking and creaking while the spring was fully extended and seated. It went away when I compressed the spring slightly. It was very clear that the noise came from within the strut body.

Without a replacement, I threw it on the car anyway. There's no creak (thank goodness) but I still have the same clunk. I re-checked the torque on the top nut with the car on the ground.

My question: is it possible for a strut to make a clunk in rotation like that? If so, I'll assume that's the issue. I need new ones anyway. If not, I'll keep searching.

The only other weird thing I noticed was that the stupid shaved top hats don't seem to be perfectly level on the bottom. I figured there's enough play in the rubber mount for this not to matter, but maybe there's a bind between the metal bushing and the metal cups? I regret not swapping to the new top hat now!

I'll put the car back up in the air to see if I can pinpoint [...]

What do you mean by replaced just the bearing? The round track of ball bearings when you open up the top hat, you replaced that only?

Also what's sitting on top of the spring, between it and the top hat? Doesn't look right.

Lastly I had a similar clunk and it turned out to be the pinch bolt that holds the strut inside the knuckle. Is that torqued to spec? I believe it's 33ft-lb.

a5m wrote

What do you mean by replaced just the bearing? The round track of ball bearings when you open up the top hat, you replaced that only?

Yes, that's right. I thought I had damaged it the last time I put it in. I didn't figure out the right way to install it until later.

Also what's sitting on top of the spring, between it and the top hat? Doesn't look right.

That's the lower rubber mount. For some reason as the Dinan springs extend it will start pinching and stretching the rubber mount in a strange way such that it doesn't lay flat. It doesn't make a lot of sense. I don't think there's a way to install them upside down, is there? I spent some time figuring this out originally and now I'm doubting myself.

Lastly I had a similar clunk and it turned out to be the pinch bolt that holds the strut inside the knuckle. Is that torqued to spec? I believe it's 33ft-lb.

Everything is torqued to spec with the suspension loaded. The wheels were on small ramps.

The large, outer rubber piece is the top spring 'pad'. It actually comes with the top hat, so nothing additional needs to be installed - the spring sits directly against it. It shouldn't be distorting that much if that's what is shown in your pic.

Were you perhaps sent an additional spring pad to install, so you have two of them stacked on top of one another? Also the writing on the spring is right side up?

"]https://www.fcpeuro.com/public/assets/products/345380/large/BMW-31302283650-2.jpg?1579891560

It only has the single rubber mount. Dinan confirmed the springs can only be installed one way. There is no writing on them.

I talked to Dinan about the rubber mount. After some back and forth, the support person checked with his production manager and sent this:

He did say that the scrunched top hat is not normal for these kits, but are not an issue. The excess pressure has to go somewhere, and as long as the top of the spring is tight and solid, its ok.

Not normal but still okay.

As far as the original clunk goes, I think it's time for a diagnosis fee. I've spent many hours on a few particularly tricky random noises on past cars. I lifted the car again tonight and couldn't reproduce the original sound. I'll get a second opinion with a wider aperture. Despite it happening right after the install, I might be wrong about what the source is.

Thanks anyway for the thoughts!

I'm chasing down a similar problem on our E91 and have ruled out nearly everything. Let us know what you figure out.

Update: the other day I realized I haven't heard the noise in weeks, if not longer. Uhh?

This might be the first time in 25 years of working on cars where a problem fixed itself.

I still need to replace the struts/shocks regardless. If I hear the noise again, I'll know it's the Dinan top hats slightly out of position or something.

I had this and chased it for a while. Turned out to be a guide bushing in the strut. Replaced the strut and all the noise went away.