[Amg2Turbo]

I tried replicating the creak by pushing down on the car with the boot open but wouldn't make the sound. Only happens while moving.

 

[Amg2Turbo]

That a good suggestion, thank you. Ill give it a try this week and let you know.

 

[Amg2Turbo]

It could be the bootlid or lock itself that makes the sound, I have a similar creak whenever I drive slow diagonally up and down from and to my parking area/carport. I haven't gotten around to looking into it yet, I suspect that it could be one of the rear doors or the bootlid that creaks, try driving on the same bumps with bootlid not fully closed, like just before the lock engages the striker to see if its quiet then. If it is, well theres your source of the creak. my CLA is a 2018 Shooting brake.

It wasnt this, tried driving with the boot open and sound still present. Neighbours think im mad though

my CLA has that creak in the rear as well, but only occurs when my car turns left and as it leans on the rear right end of the car. Does not do it, if I turn right and as it leans on the rear left end of the car. I had the suspension checked, and its not the springs or shocks. Some is not properly bolted down , and the creak is only occurring when I turn a tight left turn slowly.

Why didnt you get the mechanic to try torquing down suspension bolts. Turning left or right sounds like its the anti-roll bar, so could be a bush as the post below.

 

[Amg2Turbo]

My money is on the strut bar. Easy to test, disconnect the endlinks and go for a drive. I’m pretty confident this is your issue. If you have an H&R bar back there by chance I am 100% confident that is your issue.

the other way to test is to get under the car and hit the bushings with WD40 and go driving. That should make the squeak vanish too if that’s your root cause. But careful, this is actually a terrible idea because it’s short lived and there is a high risk of “causing” a bushing squeak if that wasn’t your root cause, and if it was, the squeak will come back in a couple days anyways.

If this is your issue, the fix is:
1. Take the bushings out, clean the junk off them, clean the bar, make it spotless and dry, reassemble.
2. if that doesn’t work, get some well respected bushing grease and reclean, apply grease, reassemble, and clean the exterior.
3. If that doesn’t work, buy replacement bushings and do #1 and #2 in order again.
4. If that doesn’t work, buy a new bar (H&R) and repeat 1 and 2.

Anyway, easy enough to test. Yes I have experienced this squeak.

thanks for the write up.

Have to disconnect both sides right? And just the top one that mounts to the hub or better to do the lower side that goes to the bar?

Before doing that Im going to wrap my phone cable mic around the bushing on the left side and go for a drive. Sound does not occur when I go over a bump with the right rear wheel, just the left or both.

I tried spraying every component with silicone and nothing got the sound to go away. I just saw this post so will try. Spraying the bush does nothing really as its so tightly wrapped around the bar nothing is getting in.

Getting to the bolts looks like a pain though. The upper bolt is near the body of the car. How best to access it? From the side or underneath?

 

[Amg2Turbo]

I get to them from under. Either on ramps or jacks. Yes both sides disconnect.

If you hosed the underside with any solvent, I'm more sure than ever it's your bushing. I totally get where you are coming from about no-way-capillary-action, but I don't agree. Not gonna fight about it or anything, I just strongly believe spraying is enough to get penetration in there.... and the subsequent squeak.

So I'm more sure now than ever that the bush is your root cause, and the solution is to unbolt it, clean the heck out of it, and put it back dry.

--------------------

For the record, I have some really nice sway bar grease (snake oil?) in my toolbox, but I never got to the point of using it. What worked for me was clean, clean, clean, and put back dry, dry, dry. I'm not sure if using purpose specific grease is a good idea or not.

I can tell you for darn sure WD40 makes it worse. When I had my squeak from crap getting in there, I hosed it with WD40 for troubleshooting pathfinding, and the squeak went completely away. I knew what was coming tho, 2 days later and it was worse than ever. That's what triggered my 1-2-3 plan above. But I never got past #1 because it worked.

Lasted 1-2 years no squeak, so I'm a few months away from being due again if the crap-accumulation is happening at the same pace.

The squeak/creak was present before I hosed anything down but I don't disagree that it can cause a squeak. If its not the sway bar bush, I'm leaning towards the lower spring arm bearing as thats closet to the road and susceptible to road salts and other things which cause failure. This will need to be pressed out with a special tool so hoping its just the sway bar bush!

 

[Amg2Turbo]

Mine are metal and sound disappeared with both sides disconnected. I then went to remove and clean the ARB bush only to find them bonded and unremovable. Massive waste of a few hours, I didn't drop the charcoal canister so the bolts from hell (for the bush mounting plate) took me a while to remove. I had to put it all back uncompleted. I will buy the rear links and bar and change them together. The link integrated bolt (pic below) squeaks when I turn it but I do not think that bolt has any movement when the car drives, rubber and links are in good condition otherwise.

Apparently (according to OEM workshop manual) the diff needs to be dropped with the shafts somewhat to access the bush mounting plates on the O/S, just to change the bushes due to the whole bar needing replacement. Never experienced this on different makes so caught me off guard.

 

[Amg2Turbo]

For me the issue was just the drop links. Didnt think those small links which don't flex when trying to move by hand would make such a loud noise. Replaced with Lemforder branded parts.