Hey guys, I’m dealing with a strange issue after changing my brake pads. When driving, there’s a clunking noise, but it goes away as soon as I press the brake pedal, even just slightly. I’ve already gone back to the mechanic, and they readjusted the pads, but the noise is still there. The moment I touch the brakes, it disappears.

I’ve attached a video for a better understanding—sorry if it’s a bit windy!

Has anyone dealt with something like this or have any ideas on what might be causing it?

I dont see a video.

Front or rear? RWD or 4matic?

Hard to say since the mechanic has looked at it again. I would say check the calipers and caliper brackets to make sure all the bolts are torqued right. Check the pistons, make sure they arent damaged and working right.

If you have a floor jack i would jack up the car completely on that end so both wheels are off the ground, spin the wheels by hand listening for the noise. Remove the wheels and spin the rotors listening for the noise. Check how the pads are sitting, should be right up against the rotors.

Could be something new and unrelated to the brakes.

I’ve attached the video again—sorry about that! My car is RWD, and when I last went to the mechanic, we did spin the wheels by hand to listen for the noise, but nothing came up. After driving it out of the shop, the sound returned the next day, but it still disappears as soon as I press the brakes.

I had that - over and again in my C240 (wagon, 4matic). The eventual solution was to adjust the metal clips - or - as much as I hate it...use OEM pads and clips. The aftermarket ones would let the pads wobble a bit in the caliper. Tried multiple brands (I had that car for 13 years and 280k /mi).

When I got my W204 it had all MB brake parts. I replaced the rotors with Zimmerman brand. Front pads I used Ferodo semi-metallic and the rear I used ATE semi-metallic and have had no issues with them at all, i think they work great. the pads looked the exact same as the MB pads that were in there, i even think the rear MB pads were stamped ATE along with the MB logo.

I followed the sheet below for where to grease. I put grease on the front calipers UNDER the anti-rattle springs. No grease at all on top of the anti-rattle springs where the pads ride. And because the pads did not have a self-adhesive pad on the back side I did apply a small amount of grease on the back of the OUTSIDE pad only, nothing on the inside pad. Every so often when I have the wheels off i will remove the calipers and clean off the anti-rattle springs, or just squirt some brake cleaner in there to knock off any built up brake dust.

For the rear I only applied grease on the caliper bracket where the pads ride. The pads came with an adhesive backing on the outside pads so no grease at all. When I happen to have the wheels off ill clean off the brake dust with brake cleaner then work some grease in that area using a q-tip.

Ok, I watched video. Yea that does sound like somethings wrong.

I would be checking to make sure the wire springs are installed right:



I would check to make sure the caliper pins are torqued:



Then double check the caliper bracket bolts to make sure they are torued right.

It could also be an issue with the parking brakes. When i replaced my rear brakes the parking brake pads were caught up on the inside of the rotors and i ended up pulling them off along with the rotor. It was a mess, pulled the parking brake pad springs right out off the dust shields. Then my dust shields were so rusted the springs hardly had any material to catch back on to. A short time later while driving the parking brake pad springs popped out and ground into the rotors. i ended up having to replace all that stuff in there.

But its hard to tell not being there able to look at it. can only guess.

The springs in that video are not at all as common as the flat metal spring...I have also seen them installed incorrectly (I know this because I did it and got laughed at by a shop in like, 2006 or something)

Looked like in the video it was in the rear. Im not familiar with all the different types of brakes on the W204 but i do know there are different ones in the front.

My fronts do not have a retention spring at all for the pads. Also the inside pad does not clip into the caliper. I see other types have the inside pads that clip into the caliper and they have a flat type spring on the outside pads. When I did my fronts i looked at the article on Pelican parts and i didnt see that flat retention spring on mine so was about to order them thinking they were missing. But no they wouldnt even fit my set-up in the first place.

Heres the pelican parts photos of the W204 they worked on, Fronts:





My W204 4matic Sport uses front pads without the clips on the back of the inner pads:





But I think the rears are the same across all models. The same as in the inner pads clip into the calipers and they have that wire type retention spring on the outer pad. Obviously I could be wrong.

What brand pads were installed? Do they have that self-adhesive backing on the outer pads?

Heres the exact rear pads I have installed. They come with a self-adhesive pad on the back of the outer ones. Maybe that prevents them from flopping around? And why I didnt use any grease on them.




Heres more info on different types of brake calipers if you dont have the ones posted above:




Heres what I used instead of the MB grease. Its ATE Plastilube.

If you don't have the retention spring, check that the caliper is moving on the guide pins. If not, remove, clean, and lightly lubricate the pins. If the caliper is not moving smoothly, it could be the outer pad rattling before it makes contact with the rotor.