**Vibration when braking**
By chance do your breaks squeal at all when you are backing up first thing in the morning (usually if it is cold outside it really squeals)?
Here is my experience on my 2014 S550 4matic. When I would back up in the morning my brakes would screech so bad people two blocks away probably could hear the brakes There is a warranty replacement for this issue. I had all four sets of brake pads replaced under warranty. Before I had the brake pads replaced, I had pulsating like you are referring to. Once they replaced my brake pads under warranty the pulsating went away.
So I believe these are somehow tied together since my pulsating went away after the warranty brake pad replacement.
Here is my experience on my 2014 S550 4matic. When I would back up in the morning my brakes would screech so bad people two blocks away probably could hear the brakes There is a warranty replacement for this issue. I had all four sets of brake pads replaced under warranty. Before I had the brake pads replaced, I had pulsating like you are referring to. Once they replaced my brake pads under warranty the pulsating went away.
So I believe these are somehow tied together since my pulsating went away after the warranty brake pad replacement.
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It's not a breaking issue its the rotors. I've had my 2015 s550 for a year and have had my rotors and breaks repaired every 3-4K miles amongst my tires are only lasting 4 months. 😬 It is in on its 5th repair and Germany as of today has recognized the issue. I hope this helps.
It is amazing to me, that a company like MB could find themselves with a weak link, in the way of easily warped brake rotors, on their flagship sedan, after so many years of producing similar systems. Does every single system need to completely change with each new model? One would think that you get brakes engineered to perfection and then LEAVE THEM THEM BE! Why fix something that isn't broken? Oh well.
It is amazing to me, that a company like MB could find themselves with a weak link, in the way of easily warped brake rotors, on their flagship sedan, after so many years of producing similar systems. Does every single system need to completely change with each new model? One would think that you get brakes engineered to perfection and then LEAVE THEM THEM BE! Why fix something that isn't broken? Oh well.
And hard stop where you end up at 0MPH and have to stay there for more than 10 seconds can warp rotors--check that, what happens is that the pads being clamped on a hot rotor allow the rest of the rotor to cool while the clamped part heat soaks. The difference between the cooling rotor and the hot rotor is what causes the distortion.
There are several solutions:
a) If you have to brake hard, take the car out of gear so you can release the brakes without going forward.
b) 6-8 stops from 90MPH-30MPH as hard as you can brake and as hard as the car will accelerate as fast as the car will accelerate will unwarp most rotors. (diesels not applicable--lack of acceleration, Don't do this within 20 miles of any city, watch for constabulary forces.)
c) drive in such a manner that you don't have to stop all that hard.
Interestingly I notice in the German Price list an option U29 - Brake system with larger front brake discs for the fairly modest price of Euro 297. The catch however is "Not in conjunction with AMG line (950)", which option I believe is very common in the US.
Stop the ‘Warped’ Rotors Myth!
Myths take hold *because either A) they seem completely logical or B) they are so often repeated that they just become common knowledge. The warped rotor myth is a little bit of both. A rotor that contributed to a pulsation condition certainly appears “warped.” Plus, everyone says it — even technicians that know the rotor isn’t *really warped will say it as shorthand.Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.
Obviously rotors aren’t invincible. They can crack, break and develop irregularities that lead to pulsation, but all of those problems start to develop in other ways that need a technician’s touch.
Starting today, remove “warped rotor” from your vocabulary. Instead, you should be both looking for and educating yourself about these terms:
Lateral Run-out:
Root causes of run-out include:• Run-out from the hub mounting face;
• Run-out from the wheel bearing;
• Sloppy resurfacing/machining procedures;
• A build-up of rust and corrosion between the rotor, hub and wheel;
• Uneven torque on the lug nuts;
• Wheel loading distortions; and
• Variations in manufacturing tolerances.
Other vehicle components can exacerbate the problems with run-out. For example, if a vehicle’s floating or sliding calipers aren’t sliding as they should, that will prevent the caliper housing from moving, and any run-out can cause pulsation. The caliper piston will move in and out as the rotor rotates resulting in fluid movement and pedal pulsation. Fixed-caliper vehicles are sensitive to run-out induced pedal pulsations as well. Fixed calipers have pistons on both sides of the rotor due to the stationary caliper housing. Excessive run-out will cause piston movement and can result in pedal pulsation. Over the past 30-years, factory run-out specification have fallen from as high as .015″ to .000″ (or no detectable run-out) for some vehicles. These tightening of the tolerances is due to changes in suspension design, friction formulations and caliper designs. When run-out moves beyond specification set by the manufacturer, the uneven application against the pad will lead to disc thickness variation (DTV).
Disc Thickness Variation (DTV):
The thickness variation is subtle, but all of these details add-up. When the thick part of the rotor is forcing itself through the caliper, the torque of the brake and the pressure in the caliper rise. When the thin spot passes through, the torque drops and pressure drops. Very small amounts of DTV can create a significant problem. More late-model vehicles are built with a thickness variation of less than 0.00078”. Thickness variations in excess of 15-microns (0.00059”) can easily generate driver complaints of pulsation/vibration.
Factors to take into account:
• The suspension. Unibody vehicles with strut suspensions are more sensitive than those with a separate frame and body.
• Wheel bearings. Unitized bearings, in particular, are pre-loaded and have zero play, which means there is no wiggle room for run-out. Any high and low spots will scrape the brake pads with every revolution of the rotor — braking and non-braking.
• Calipers. Some have lower running clearance and higher initial mounted lateral runout.
• Abrasive lining materials.
The rotor can also show friction variation around its circumference. Any spot that has more slip or stick to it relative to the rest of the rotor will result in different levels of torque. Variations in friction will generally be the result of corrosive or contamination effects. There will most likely also be DTV, but the friction variation is possible without DTV. Friction variations can occur when a vehicle has sat un-driven for extended periods of time...especially when subjected to excessive moisture which can be noticed as a build-up of an oxidized (rust) surface on the rotor's face.
Cold Brake Roughness:
That mentality is troublesome when it comes to brakes — saying a rotor is warped easily puts the blame on an ineffective part that needs to be replaced when that isn’t the case. Understanding that a warped rotor is a myth is to understand that there are other causes for the braking condition and additional work is needed to do the job right. This may seem like a matter of semantics, but mis-characterizing the root problems of pulsation just perpetuates the myth.
Now that you fully UNDERSTAND these terms and have read all the way down to this point, you can understand that the symptoms here are ALL related to lateral run-out (uneven wear on the rotor surfaces) and has been caused/perpetuated by rotor-hub misalignment. I can't begin to relay to you the number of multiple-decades-experienced professionals that have yet to understand these terms and effect the proper remedy, which leaves the consumer coming back to the repair shop after 3-6 months/5K-10K miles for the SAME problem/symptom. Replacing the rotors will effectively restart the uneven wear process, but in so many thousand miles, it will return and perpetuate itself. You'll find yourself going through this over and over and over and over and over and over again, until the car is out-of-warranty and you are either paying out of your own pocket or you end-up trading the car out of frustration and/or economics.
The reality of the matter is that if you hit a curb, pothole, etc. an ever so slight (recall above about minute thicknesses and measurements) change in the geometry of the suspension and/or steering, but mainly the axle hub. With a new set of rotors the thickness of the rotor is uniform on the surface, but as the minute difference in the hub mated against the rotor, the rotor is ever so minutely rotating squarely within the caliper, and over time this repeated process wears the rotor surface unevenly. You follow me so far? So, as the difference in wear across the surface of the rotor continues, you will end-up with a disc thickness variation (DTV). The reason that this keeps coming back over and over again is that the cause of the problem is not a bad rotor, but rather a misalignment between the hub and the rotor. In older cars, this minute run-out was relatively unnoticeable until the run-out was excessive. But on today's cars and their advanced braking systems and suspensions, it's infinitely more noticeable. The automotive industry has a solution, it's called an 'on-the-car brake lathe' and the process is called "rotor matching". Now, before you go screaming "Mercedes-Benz rotors can NOT be lathed!!!"...hear me out. What these specialized lathes do is match the rotor to the hub of the car to insure that the assembly of the two has no or 'within-tolerance' run-out. A lot of shops are adopting this technology and most dealerships now have these in their arsenal. The machine attaches to the hub/rotor assembly and shaves whatever number of microns off of the rotor to insure that the entire assembly is true and does not run-out/vibrate within the caliper, causing uneven wear resulting in DTV. This newer technology is being applied when new brakes are installed with new rotors to vehicles now to insure there is no consumer returns/complaints.
I'm not sure I have effectively relayed exactly what all is going on with this process, but I did find a video which briefly describes the cause of the problem and how rotor matching works
This hub-rotor alignment process solved the drive-ability/braking pulsation problems with the W222's in our fleet and NONE, ZERO, ZILCH of the vehicles has had a recurrence of these braking pulsation symptoms between brake jobs.
Last edited by ChesapeakeLimo; Aug 8, 2018 at 05:11 PM. Reason: adding video link
You proud owners of the W222 have obviously raved, enjoyed and shown people the tech features of your beautiful Mercedes and feel good about the technology. Guess what? If you know how to drive, you don't need these features. Turn that crap off immediately! In other words DISABLE the features altogether!, as you have options on your steering wheel settings and controls to do so. You do not need to have them enabled. I guarantee this will minimize the brake issues and prolong the life of your pads and rotors. (I will bet every dollar I have on this fact.)
Last edited by jagwaar; Jul 6, 2020 at 03:03 PM.
Us proud owners of the W222 have obviously raved, enjoyed and shown people the tech features of your beautiful Mercedes and feel good about the technology. Guess what? If you know how to drive, you don't need these features. Turn that crap off immediately! In other words DISABLE the features altogether!, as you have options on your steering wheel settings and controls to do so. You do not need to have them enabled. I guarantee this will minimize the brake issues and prolong the life of your pads and rotors. (I will bet every dollar I have on this fact.)
Last edited by jagwaar; Jul 6, 2020 at 04:30 PM.









