Paul_mez

Decided to treat my 2012 C63 to a clean yesterday. Got the hose pipe out and washed the wheels. Put the car in the garage over night. The following morning (I used the parking brake over night) I released the parking brake but the parking brake was stuck and needed some small effort to free them up (with a small clunk noise). They released and I went about my trip. When I was driving at low speed there is a terrible grinding noise coming from the rear. As if the metal shield is rubbing on the rotor. If I apply the parking brake a little the frequency of the noise changes.
I got home and jacked the car up. Fired up the compressor and cleaned the area with air. Thinking it was dust or dirt getting dislodged. I opened the pads on the caliper to make sure it wasn't the pads.

Backed it up and the noise is still there.

Any ideas where I should be targeting? Are the parking pads inside the rotor? The car has 21k miles so don't think they would be worn out.

When the car is jacked up, with the parking brake on the wheel rotates a few degrees back and forward. Is this normal? Or a sign my parking pads are broken and were damaged?

Any help or advice would be appreciated.

roadkillrob

Pads are inside the rotor yes, you would have to remove the rotor to get a good look at the parking brake mechanism. I use a lot of water when washing my wheels sometimes the power washer and have never had an issue, but I have also never put the parking brake on after washing. It sounds like the parking brake rusted to the rotor just as the pads usually rust to the rotor after washing and take a little effort to move the car the first time.

I would think it would stop after your small trip if it was just some rust on there, so would be more concerned maybe some pad material came loose inside the parking brake (it just works like a little drum brake inside the rotor) and probably is best to take the rotor off and have a look.

Paul_mez

Thanks roadkillrob. I took the rotor off and found a broken spring all mangled up. (see pics). Rest of the pad looks ok.

Odd that 1 month ago I had the parking brake assembly replaced by Mercedes, since it lost it's return feature in the pedal under the dash.

I'll head to the local Merc dealership and get a replacement hardware kit and caliper mounting bolts tomorrow.