Vanquish59

Hi guys, recently acquired a 2019 S63 4matic sedan with 25,000 miles on it. The car still has warranty on it and I have had the car for about a week now. Drives amazingly except one problem, the REAR brakes squeal loudly. The problem only occurs after I have warmed up the brakes on a spirited drive (probably cause of metal expansion). On a speed of 5mph, the brakes squeal when driving and go away when braking. It's like the brake pads and rotors are constantly touching / caressing each other. The brake pads (both front and rear) were changed 1000 miles ago, per carfax. I've read online and there are so many different scenarios, glazed pads, loose caliper bolts, no grease when applying new brake pads, etc. Anyone have similar issues and solved them? Thank you

attached sound clip

PatPend

Try bedding the brakes. A few easy stops from 40 mph to 5 mph to warm them up, then 5 hard stops from 60 mph to 5 mph. Don't stop completely and brake hard enough but just shy of activating ABS.

Vanquish59

Didn't solve

W205C43PFL

Good read I think: https://mbworld.org/forums/sedan/868...ke-squeal.html

Vanquish59

Thank you, since i bought the car a week ago i convinced the dealer to let them look at it and see if they can find / change anything. It's ****en annoying af.

W205C43PFL

I agree it is annoying but it might be the nature of the beast, however there might be ways to at least quiet it down a bit, it is still very loud when windows closed? I mean the S-Class sound insulation is second to none (should be after).

Vanquish59

Inside, windows closed you don't hear anything. Outside you can hear it, especially in insulated places like parking lots etc. The front wheels make no noise, it's only both back wheels. Feels like the caliper isn't being released properly, maybe the bolts need lube, etc. Only happens when car is warmed up, slow speed. You can definitely hear the caressing of some kind.

Attached sound clip

W205C43PFL

Ya that is typical MB brake squealing, hopefully there is a way to lower the volume or even eliminate it.

Vanquish59

Attached sound clip

Vanquish59

Attached sound clip

superpop

I have a 2019 S63 with 24K miles on it now and I replaced the factory pads with Z23 (Rear Z231681) and Z26 (Front Z261291) Carbon Fiber Ceramic Pads. Mine did not squeal but I got sick of all the brake dust. With these new pads I have zero noise and zero dust with no real difference in performance that I can tell. If you are not comfortable installing them, any competent brake shop should be able to do the swap for you. That is where I would start.

Vanquish59

Thank you, can you listen to the sound clip too, would really appreciate your insight.

ChrisHimself

can you show me a picture of the rotors? lets make sure we don't have uneven wear, deep grooves

Vanquish59

Back tire rotors

superpop

Rotors look fine. Could be a sticky caliper. I would start by having a brake shop pull the rear calipers and give them a thorough inspection and then grease all of the appropriate mating surfaces.

Vanquish59

The thing that baffles me, well maybe I'm not hearing correctly, is that BOTH rear tires making the same noise at the same time. Maybe it's one but noise coming from both sides, who knows. Is there any possibility that there might be some loose bolt, or some **** on the rear part of the 4matic system? The bridge perhaps? I attached a sound clip to the original post.

superswiss

Yeah that doesn't' sound right at all. The brake pads are technically always in contact with the rotor, but there's no pressure applied. This does sound like there's light pressure being applied due to potentially a stuck piston. I would expect some splotching of brake pad material, though eventually if that's the case. Might be a good idea to use an infrared thermometer and see if the rotors get unusually hot. If the pads are touching then you'd see higher than expected rotor temperature just driving around.

I do have to say that for having been changed supposedly only 1000 miles ago, those rotors are quite rusty already. The rotor surface looks ok, though. What's your environment like? Do you frequently park the car with wet brakes? Driven in salt during the winter and or parked outside? The pads are semi-metallic, so the brake dust does rust as well if exposed to a corrosive environment.

Vanquish59

Rotors are very hot, but not red, no noise from front, only rear. Rotors haven't been changed, only pads. Car has 25k miles on it. No wet, no salt, sunny California. Just too many things tbh, stuck calipers, rotor back plate, rocks between rotor and pad, cheap pads, etc. Pads were changed at a benz dealer, previous owner. Got the car a week ago, besides this noise, car is phenomenal. Already put 600 miles on it.

superswiss

Then the rotors might be worn below their minimum thickness. Can you feel a pronounced lip at the outer edge of the rotor surface with your fingernail? The rear rotors are generally good for two sets of pads, but it's not ideal. The grooves in the rotors from the previous pads can prematurely wear the new pads if the rotors aren't turned, but there isn't really enough material on these rotors to turn them, though. They have only about 1 mm of allowed wear before they reach the minimum thickness.

Vanquish59

Dealer sent me the paperwork for the rotors before purchase. Mm measurements, etc. Said they got at least 50-75% left, brakes work amazingly well, no screeching. It's only when I go slow, and rotors are hot I get the squealing noise like something is slightly scraping, rubbing. Doesn't happen when cold.

Vanquish59

See how the holes have a sort of dragging slide mark?

superswiss

Yes, I do, and with the different lighting that looks like it's smearing pad material over the rotors, so I would also conclude that you most likely have a stuck caliper.

ChrisHimself

those look fine I've seen worse. everythings wearing as it should. I'm a bit concerned because you're not to replace just the pads on these cars which can cause these issues. You'd have to replace the pads again so I'm hoping I'm wrong.


the OEM 2-piece rotors are brutal, $1300 apiece. You can get by by switching to other 360x26mm rotors like the Brembo 2224232012KT1 or whatever the part number for Zimmerman is. They will weigh more than the OEM design. the OEM brake compounds are also just loud in general which doesn't help. I have the same size brakes on my car and went straight to ceramic

Vanquish59

I mean what are the odds of a stick caliper on both wheels? Taking to dealer this week

Vanquish59

This is the 3rd brake pad change, per carfax in 25k miles. The last owner said he never heard squealing noise. Might be pads got changed, no lube, no good quality to prepare the car for sale, who fkin knows. The car has 3.5 years of warranty, factory + CPO left. However no wear n tear coverage.