[SS-Traveller]

A friend's 2016 Mercedes C200 Avantgarde (chauffeur-driven) has this awful low-intensity grinding / grating / groaning noise emanating from the brakes. He is seriously upset about the noise, and repeated visits to the MB dealer have not been fruitful in sorting out the issue. They have pointed out that all other C200s have this noise too. However, the gentleman's E350 and SLK 350 do not have this kind of noise. Curious, I checked another friend's C200 and E250, and sure enough, the C makes noise but the E does not.

Use good quality headphones to listen to the noise in the video:

https://youtu.be/uBmG3tl8sMw

The noise comes when the vehicle is allowed to crawl at a millimetric pace by reducing the pressure on the brake pedal. This is not related to the brakes being wet. The chauffeur reports that the brake noise is more prominent on a dry, hot day.

So the friend asked me to try if I could sort out the issue.

I made sure to heat up the brakes well and then try to elicit this noise, and the noise persisted. Had the pads cleaned out, the noise subsided but came back in a few kilometres. The pads are OE TRW pads, and the car has hardly run 6000 km (the other friend's C200 which I checked had run 8800 km). The noise has been present since when the car was brand new.

The brake pads. Just the one of each pair has the TRW branding. I thought that's odd:

Since the noise would not go away with simple cleaning, there were 2 options to try out:

1. To replace the pads. However, all OE pads seem to make similar noise. BHPian dip27in suggested that Brembo pads might eliminate the noise. But procuring genuine Brembo pads for the C200 is a little dicey in Delhi.

2. Use an anti-squeal paste to damp the low-pitch vibrations from the pads & calipers. I narrowed down to a Liqui Moly product available on Amazon. Since this is an entirely reversible process as well as easier to procure the product, I thought I'd give this a try first.

Work begins:

Cleaning out the pads, rotors and calipers with brake cleaning spray. Used a full can of STP, followed by another can of Würth spray. Würth seems to dry out slower, but cleans better.

This is the Liqui Moly product, and the product video:

https://www.youtube.com/watch?v=qhDxsHHhuj0

Unfortunately, Amazon omitted to send the dispensing brush, and sending back the product and asking for a replacement would take another few days. So we dispensed the paste and applied it using nitrile gloves. A little overapplication here, but we were very, very careful to avoid getting the stuff on the friction surfaces.

Work in progress:

That's how it looks finally:

Before opening up the rear brakes, one needs to go through this process:

https://www.youtube.com/watch?v=UJstw4DdgEw

The result: The next couple of days, we had heavy rain showers in Delhi. I drove the car around for about 50 km, and the noise gradually disappeared completely. The owner's chauffeur collected the car, tried to elicit the noise and somehow managed to get about 10% of the original noise, which seemed acceptable.

2 days ago, I got a call saying the noise is back.

I am told by some experts that ALL automatic transmission cars WILL make such a noise, and there is no workaround for this. Mercedes Service Centre has made it clear to my friend that this is a noise that is present in ALL C200s, and he's got to live with it!!

But there is no such noise on the E-class or SLK.

Now what? Any suggestions welcome.

[Rudra Sen]

Mod note: Thread moved to 'Technical Stuff'.

[drifter]

This is normal. Have used MB and non-MB pads. No difference. Easier to live with the problem than have people open up those calipers.

[R2D2]

I think it's a design or a manufacturing defect in the pads/rotors. When my car was new the front pads squealed loudly much like a truck brake and were promptly replaced under warranty with another set. That solved the problem.

As long as the car(s) are under extended warranty it's better to stick with the manufacturer's OEM parts. Otherwise there a several aftermarket rotor and pad options for these cars.

[ACM]

My close friends C200 has the exact same issue.
Checked with my BIL in US evidently his E400 and S500 both had the same issue there as well and in all cases started in the first 5000kms or less.

[androdev]

Internet forums are full of MB brake screeching complaints. I suspect this problem is due to certain batch of brake pads and not aware of any fix that actually works. Certainly not worth the time chasing a solution.

After the recent brake pad change, my S class makes screeching sound when slowly coming to a halt (like when you are stopping to pay the toll). I took it to the dealer, they did something but it clearly did not help. I will just wait for the next brake pad change. It doesn't bother me much, especially with S class windows up, you can't hear a thing even if someone is drilling a hole into your car.

I am planning to do a proper bed-in procedure when I find time.

http://www.stoptech.com/technical-su...-system-bed-in

When a system has both new rotors and pads, there are two different objectives for bedding-in a performance brake system: heating up the brake rotors and pads in a prescribed manner, so as to transfer pad material evenly onto the rotors; and maturing the pad material, so that resins which are used to bind and form it are ‘cooked' out of the pad.

The first objective is achieved by performing a series of stops, so that the brake rotor and pad material are heated steadily to a temperature that promotes the transfer of pad material onto the brake rotor friction surface. There is one pitfall in this process, however, which must be avoided. The rotor and, therefore, the vehicle should not be brought to a complete stop, with the brakes still applied, as this risks the non-uniform transfer of pad material onto the friction surface.

The second objective of the bedding-in process is achieved by performing another set of stops, in order to mature the pad itself. This ensures that resins which are used to bind and form the pad material are ‘cooked' out of the pad, at the point where the pad meets the rotor's friction surface.

The bed-in process is not complete until both sets of stops have been performed.

For a typical performance brake system using street-performance pads, a series of ten partial braking events, from 60mph down to 10mph, will typically raise the temperature of the brake components sufficiently to be considered one bed-in set. Each of the ten partial braking events should achieve moderate-to-high deceleration (about 80 to 90% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between.

Depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat by around the fifth stop (also about the time that a friction smell will be detectable in the passenger compartment). This does not indicate that the brakes are bedded-in. This phenomenon is known as a green fade, as it is characteristic of immature or ‘green' pads, in which the resins still need to be driven out of the pad material, at the point where the pads meet the rotors. In this circumstance, the upper temperature limit of the friction material will not yet have been reached.

As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when all ten stops have been performed - not before. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied. After cooling the vehicle, a second set of ten partial braking events should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.

[patron]

I have a 2018 C 220 and have the same noise when braking at slow speeds. A friend has an A4 and I noticed the same sound too. Though irritating, the braking is confident and sharp. So will live with it.

[R2D2]

Some cars (and I think all the lux models for sure) have their brake systems bedded-in at the factory but new car owners are advised to go easy on the brakes for a few 100 kms. I don't believe most owners are even aware that brakes require bedding-in.

I performed a DIY on my car and installed new rotors (KBX and Bosch) and brake pads (Bosch) on all 4 wheels a couple of months back. Given all 4 friction surfaces were new a bedding-in procedure was absolutely required. I was extremely wary of the new parts' performance and started the bedding in with city driving.

IMO city driving/braking is a perfect way to gently run in the brake pads and rotors but the chief draw back being the hot components don't cool down sufficiently due to lack of air flow in slow city traffic. You are advised not to keep the hand brake engaged OR the brake pedal depressed at traffic lights.

I switched off the engine at the stop lights preferring to leave the car in gear. But even after babying the brakes, the rear brake pads (my car's braking is biased to the rear) left a very light imprint on the rotors. Over time these imprints can cause brake judder and vibrations. Light brake pad imprints can be removed by driving at moderate speeds and braking OR the more stubborn ones using sand or emery paper. I did a few 100 km of running within the city. The brakes used to get really hot.

The next was a highway run with 3 passengers and me driving. More weight means more braking effort = more heat generated, which is essential for bedding in. A few stops from 90-100 kmph down to 10, never coming to a complete stop, and then moving back to cruising speeds helped do the job. Speed breakers and toll booths on certain stretches of the old Mumbai-Pune hwy make it easier to do this as the traffic is forced to slow down any way.

The discs now have a nice even patina of brake material, a greyish dusty coat, evidenced by running my fingers across the surface once they had cooled off. But I'll be bedding-in the brakes for at least 400-500 km to extract the best possible operating performance.

[NTO]

Originally Posted by SS-Traveller

Now what? Any suggestions welcome.

I used to get a similar noise (similar to what I heard from the video that you've shared). I used to open the calipers, clean the brake pads, clean the rotor and the sound used to appear shortly in a couple of days. Later I realized, this was due to the way the wheels were cleaned. If the water jet used to clean is made to hit perpendicular to the wheels, the brakes are made wet with some water seeping into the system of the brakes. Not sure if this would solve the problem on the C after all that you've tried, but try to advise the cleaning person to spray clean the wheel with the water jet forcing water parallel to the wheels so that the brakes are not affected.

[redindian]

Originally Posted by patron

I have a 2018 C 220 and have the same noise when braking at slow speeds. A friend has an A4 and I noticed the same sound too. Though irritating, the braking is confident and sharp. So will live with it.

I have had similar experience on my C220 for the last 18 months. I followed up with multiple service center visits and even an escalation to Mercedes India. Merc India promptly sent their technical expert to help , but the problem still persisted even though we changed pads.

In the C220d ( which is diesel vehicle with higher torque than c200 ), this problem manifests additionally as a frustrating groaning noise when the brakes are not warmed up enough and you come to full stop / near stop. The grinding noise also happens when you slip the brakes at crawl speeds.

I believe this is probably due to the brake pads being not "soft" enough when cold, and the excessive use of aluminium parts , which probably resonate due to the brake shoe vibrations. Problem disappears once brakes warm up , alternatively if I had a spirited drive the previous day ( e.g. high way run with a lot of braking) , the problem is non existent ( probably because of a fresh layer of brake pad getting deposited on the discs)

No solutions yet, but some things on my list of To-Dos include trying out softer pads ( at the risk of sacrificing brake pad life) or trying out more expensive ceramic pads from other brands like brembo - will probably try this out in a few months when i get some spare time to follow this up.

[quickdraw]

I remember watching this video at Porsche dealership a while ago, maybe it should shed some light on the phenomenon?

https://www.youtube.com/watch?v=fUNHb9O52WQ

[NYMEX]

My new C-200 mercifully does not have this problem with the brakes.

However it had wiper juddering & door rattling noise which was reported and attended in April 18 & July 18.

Despite my advise (based on intensive experience of car repairs & engine overhauls) the wiper blades were finally changed only after the 3rd time.

The door seals were changed in the 3rd visit but the beading was left intact. Now the beading is being procured which had thermal deformation, due to shut doors for 6 months in the stock yard, and hence the wind noise.

A couple of days back I went to show the i10 for very low mileage. The service adviser assured me that everything was all right. I forced him to check the plugs & leads, it was found that 1 plug and a lead were short. Got all 4 sets of plugs & leads replaced since the car was already 5 years old.

The lessons learned are :
1) The quality of European luxury cars is worse than that of ordinary cars costing a fraction of the price.
2) The service supervisors have fancy suits and will explain away every defect/fault with the single magic words - 'electronic settings'.
3) The mechanics across dealerships have no clue about fault diagnosis

PS - My Corolla Altis (2009) remains my 'go to' car for incident free road trips.

[patron]

Originally Posted by NYMEX

wiper juddering.

Another identical problem but I never realized this was an issue. Though quite irritating, thought it was by design. Was living with those wipers. Now I have to complain too.

This is fast becoming a C class niggles thread.

[SS-Traveller]

Originally Posted by R2D2

I performed a DIY on my car and installed new rotors (KBX and Bosch) and brake pads (Bosch) on all 4 wheels a couple of months back. Given all 4 friction surfaces were new a bedding-in procedure was absolutely required.

Only problem is, this vehicle and its chauffeur drive more sedately than I do my bicycle. Therefore, right from the beginning, brakes bedding-in wouldn't have happened, and nor would it happen even if the entire set of pads and rotors is changed now. But there seems to be no cut-and-dried solution to make that noise go away.

Originally Posted by patron

This is fast becoming a C class niggles thread.

But the brake noise is certainly irritating enough to be considered more than just a niggle. The friend had escalated the matter to MB in writing, yet no solution has been arrived at in over 2 years of ownership. It's so frustrating, I'm almost inclined to spray a bit of silicone oil on the rotors to stop that damned noise! (Just kidding)

[R2D2]

Originally Posted by SS-Traveller

Only problem is, this vehicle and its chauffeur drive more sedately than I do my bicycle. Therefore, right from the beginning, brakes bedding-in wouldn't have happened, and nor would it happen even if the entire set of pads and rotors is changed now. But there seems to be no cut-and-dried solution to make that noise go away.

I confess to have spent an inordinate amount of time researching braking systems both pre and post DIY. The car has an ABS system and it is the first time I've ever changed my car's brake pads and rotors. I wanted to get it done right since lives depends on it. What remains now is re-torquing all the caliper and caliper carrier bolts to specs after the 'bedding-in' is done.

In your friends case, the owner could drive the car himself and bed the brakes in. Unless of course he doesn't drive at all. It's pretty easy. Just do about ten 60-20 kmph runs, allowing cooling off time between the sessions. And then take her out on the hwy to bed them in at higher speeds doing about half a dozen 100-20 braking sessions, never coming to a complete stop and again giving ample time for the kit to cool down. I stress the cooling off period is necessary to avoid warped rotors. Just follow that Stoptech article and you should be fine. Stoptech BBK bedding in procedure

Most brake pad and rotor manufacturers provide bedding in procedures for their products. There are a few variations between procedures so I'd follow the manufacturer's suggestions.

If this were a chronic problem with my luxury car I'd change the rotors and pads for sure once the vehicle was out of warranty. EBC, Brembo, Stoptech, Textar, Bosch are among the several manufacturers of braking systems that offer excellent solutions for not just big brake kits but bolt on OEM pads and rotor replacements too. Most EU cars have it good in terms of aftermarket options and upgrades

@karan561 got a Stoptech BBK (drool) for his BMW 328i E46 upgrade project. Stoptech BBK

But the brake noise is certainly irritating enough to be considered more than just a niggle. The friend had escalated the matter to MB in writing, yet no solution has been arrived at in over 2 years of ownership. It's so frustrating, I'm almost inclined to spray a bit of silicone oil on the rotors to stop that damned noise! (Just kidding)

That noise isn't going away even if you had applied Permatex ceramic paste (or similar) to the pad clips, ears and back of the pads. It may solve the problem temporarily but it will be back for sure just as you mentioned in the first post. IMHO this common problem with MB C class cars lies in combination of the materials selected to manufacture the friction surfaces. I'm more inclined to fault the the pads than the rotors.

Hey my friend has a 2011 W204 C250 and luckily for him the brakes don't squeal or rumble.