I've been having this awful groaning + popping sound coming from the rear of the car for the past few thousand miles. It sounds like a suspension component, which is odd to me because I recently replaced a bunch of bushings about 20,000 miles ago.

I have replaced in the rear:
-sway bar bushings
-sway bar endlinks
-rear struts
-rear strut mount bushings

I got the car on jacks and looked under, but couldn't find anything wrong, so I went to three different mechanics and got three different answers. The first shop told me the strut mount bushings had gone bad again. Thought not a big deal, replaced them, the noise was still there. The second shop told me the rear sway bar endlinks were worn out. I had replaced them 20,000 miles ago too, but I saw end links were pretty cheap at Autozone, so I replaced them anyways. The old ones did feel a little loose to me, so maybe they did need replacing, but the awful noises remained. The third shop told me my front control arm bushings were bad. I have no idea where they got this from, as I recently replaced the control arm bushings, and the noise is only coming from the rear of the car. I have come to the conclusion that most of these shops are as clueless as I am or like just pulling things from their a**. Probably the latter.

Anyways, I give up asking mechanics for advice. I'm sure it is something stupid obvious I overlooked so I am asking you guys instead. The car only makes the noise when I'm driving on an uneven surface, like going over a speed bump with the right wheels off and the left wheels on the bump. Or when turning into an angled driveway. I don't hear it at all during normal driving, or even spirited driving. I should also mention the car also handles fine, it doesn't feel like there is anything wrong.

Any help/ advice would be appreciated. I attached a video with sound below. I'm tired of passengers asking if my car is falling apart. :(

Groaning sound: https://drive.google.com/file/d/1JDr...ew?usp=sharing

 

From your description of when the sound happens and what it sounds like, my gut says sway bar bushings. Least invasive check would be to pull the brackets and lube the bushings.

 

The latter, while deftly attempting to relieve you of the contents of your wallet. But, these guys are petty pick pockets compared to the Stealerships.

Would inspect and re-torque everything you listed as a start, and anything that got undone / loosened / removed to make way for what got replaced on that list.

 

With noises last thing touched first thing suspected.

You touched a lot of things.

But given under the circumstances the noise appears I'd have to go along with njaremka: Sway bar bushings.

 

Hmm, the sway bar bushings are easy enough to pull and check. I'm travelling right now but when I get back to the car in a couple weeks I will take a look and update you guys. The current ones have only been on there though for 20k miles. Is it possible for them to go bad this fast? I'll admit, I am an aggressive driver and canyon carve a lot (I'm trying to tone it down, it's just difficult when these cars are so fun). Any other suggestions?

 

Check the bushings first. If they are the source of the noise then I guess you need to explore a solution.

I fitted -- machined actually -- aluminum sway bar blocks with Delrin bushings for a car of mine for the front sway bar. Even though Delrin is supposed to have good lubricity I installed grease fittings and greased the bushings every oil service. Rear sway bar bushings were rubber and remained quiet..

 

You can remove the sway bar links, drive it and see if the problem still exists. If not, your issue is with your strut, not necessarily with the mount. I was having a similar issue and finally figured out that the strut was completely suppressing and hitting the upper mount. Replaced the strut (Monroe QuikStruts) and fixed the problem.

 

Could it potentially be the trailing arm bushings? That's the only thing back there I haven't replaced. The car has 131k miles so it's probably on its way out if not already bad. It just seems surprising to me that my rear sway bar bushes would be bad after 20k miles. I do have an aftermarket H & S sway bar back there too, and from what I understand the bushings are lifetime and shouldn't require any maintenance? Or so their site says... Any validity to this or is this similar to Mini's "lifetime" fluids?

 

Aftermarket rear sway bar? I am now convinced it’s your rear sway bar bushings. Aftermarket bars use urethane bushings, which require lubrication. Once the lubrication wears out or washes away, the bushings will get noisy. My new recommendation is to remove the bushings, clean off any grease residue, wrap the sway bar with 4-5 turns of Teflon plumbers tape, and reinstall the bushings.

 

Believe you already know the answer to that question. BMW's idea of 'lifetime' differs from that of the general public; in their deceitful lizard brains, they mean 'lifetime' of first ownership, so maybe 36K miles. Not the lifetime of the car.

No rubber holds up indefinitely even in a climate controlled museum. It ages, it cracks, it loses its elasticity, gets brittle etc. Polyurethane is the preferred choice for long(er) life replacement:

https://www.outmotoring.com/mini-coo...2014-2015.html

That said would first check what was touched per the above, and also look at struts as @cooper48 recommends before delving into a potential new issue.

 

Alright, I will give the sway bar bushes a shot first. I'll be reunited with my car on the 2nd so I'll update on how it goes.

 

Pulled the endlinks off last night and took the car for a drive. The creaking sound was gone! So I guess it was the sway bar bushings. I popped the bushings out to lube them and both were torn, so I'll order some replacements and hopefully that fixes this issue.

Here's an image of one, the other side is similar: https://drive.google.com/file/d/1nXA...w?usp=drivesdk

Is this normal after 30k miles?

This did not eliminate all the sounds though. There is still one fairly quiet popping sound coming from the passenger side at the rear. I was able to replicate it by putting a jack under the rotor and raising it up. It's audible when the strut is almost fully compressed and audible when I let the strut down. I still had the endlinks disconnected. Only happens on the passenger side. Here's a video: https://drive.google.com/file/d/1nWn...w?usp=drivesdk

It doesn't sound like it's coming from the strut or the strut mount. Trailing arm bushing? I had a look at both of them while I was under the car, both look dry and cracked. Just wondering if this is likely to be the source of that noise.

 

That bushing looks like I would expect from a dry poly bushing

 

So what about that popping sound when I jack the rotor up then?

 

Sounds like something is binding and then releasing. I would go through that jacking exercise again, but crawl under the car to try and pinpoint where it’s coming from.

 

Went under again today while I was replacing the bushings. I still cannot really tell where exactly it is coming from, but my best guess would be near the strut mount? If I put the wheel back on and wiggled it with my torque wrench I could replicate it easily. It sounds like metal on metal. Here's a clip: https://drive.google.com/file/d/1udS...ew?usp=sharing

Honestly, I didn't spend as much time under there as I'd liked. Might check again next time I get a little free time. Thoughts though? Would the next step be dropping that strut? Would the upper/lower rear control arm bushes be worth taking a look at? They have never been replaced afaik.

 

So I went under ONCE again and just my luck. Couldn't replicate the noise anymore with the jack. It's still there, and it's driving me a little crazy, but ever since I did the sway bar bushings that awful groan is gone, so atleast it's better. I really do not understand what could be causing this. I was thinking it was a strut mount bushing but that was replaced 5k miles ago.

 

So I've decided I'll mess with it again when I feel like it but not make it a priority. I can tolerate it for a little I'm going to drop the strut and check the mount bushing and check it out when I get bored. It will be pretty obvious if the bushings are bad, right? They would be uneven and flat probably?