Front Brake Pulsations at 6K miles
Thread Starter
Member
Joined: Nov 2015
Posts: 118
Likes: 37
From: Dominican Republic
2022 G63, 2023 GLA 45S
Front Brake Pulsations at 6K miles
A few weeks ago I purchased a pre-owned very low mileage (6k) 2021 S580. I've mostly been on the AMG side of this forum (GTC convertible, GLA 45S plus, G63 and currently a new GT63s e performance). Very pleased with the car: comfortable ride, good power from the detuned AMG motor, nice design and all the creature features.
Last week I took my first extended highway drive and noticed the brakes pulsate when I apply them at higher speeds, something imperceptible at urban speeds. I tried a series of hard brakings at higher speeds to see if it was due to residues on the discs but that did not help. My first suspects are the front discs but it's hard to believe they've gotten out of shape with such low miles, even though I've read that can happen if they've been exposed to rapidly changing temps (ie extended hard braking and then suddenly cooled with water). This morning an MB service tech suggedted it could be improperly torqued wheel bolts (will check them tonight). Any other suggestions? Thanks
Steve
Last week I took my first extended highway drive and noticed the brakes pulsate when I apply them at higher speeds, something imperceptible at urban speeds. I tried a series of hard brakings at higher speeds to see if it was due to residues on the discs but that did not help. My first suspects are the front discs but it's hard to believe they've gotten out of shape with such low miles, even though I've read that can happen if they've been exposed to rapidly changing temps (ie extended hard braking and then suddenly cooled with water). This morning an MB service tech suggedted it could be improperly torqued wheel bolts (will check them tonight). Any other suggestions? Thanks
Steve
Out Of Control!!
Joined: Nov 2018
Posts: 11,400
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
Most commonly pulsating brakes are caused by uneven pad deposits on the rotors. Can also be caused by warped rotors, or if rotors overheated at some point and developed high spots. Could also be rotor runout, that's if the rotor is not true to the vertical axes and that can be caused by over torquing the wheel bolts. You will only know if you have the rotor runout measured properly. This will also show if you have high spots or uneven pad deposits.
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
Yeah my guess is uneven pad deposits ("warped" rotors)...although I have never had that issue on either of my S Classes even though it was a problem I always dealt with on other cars.
MBWorld God!
Joined: Dec 2019
Posts: 32,222
Likes: 6,281
A few weeks ago I purchased a pre-owned very low mileage (6k) 2021 S580. I've mostly been on the AMG side of this forum (GTC convertible, GLA 45S plus, G63 and currently a new GT63s e performance). Very pleased with the car: comfortable ride, good power from the detuned AMG motor, nice design and all the creature features.
Last week I took my first extended highway drive and noticed the brakes pulsate when I apply them at higher speeds, something imperceptible at urban speeds. I tried a series of hard brakings at higher speeds to see if it was due to residues on the discs but that did not help. My first suspects are the front discs but it's hard to believe they've gotten out of shape with such low miles, even though I've read that can happen if they've been exposed to rapidly changing temps (ie extended hard braking and then suddenly cooled with water). This morning an MB service tech suggedted it could be improperly torqued wheel bolts (will check them tonight). Any other suggestions? Thanks
Steve
Last week I took my first extended highway drive and noticed the brakes pulsate when I apply them at higher speeds, something imperceptible at urban speeds. I tried a series of hard brakings at higher speeds to see if it was due to residues on the discs but that did not help. My first suspects are the front discs but it's hard to believe they've gotten out of shape with such low miles, even though I've read that can happen if they've been exposed to rapidly changing temps (ie extended hard braking and then suddenly cooled with water). This morning an MB service tech suggedted it could be improperly torqued wheel bolts (will check them tonight). Any other suggestions? Thanks
Steve
Is there a lip on the rotor by chance?
Out Of Control!!
Joined: Nov 2018
Posts: 11,400
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
It's not unusual for it to only be felt at higher speeds. At higher speeds the frequency at which the pads hit the high spots is much higher, amplifying the vibrations, and high-speed braking generates more heat, which can cause already uneven rotors to expand, making the high spots even higher. As conditions worsen, it can eventually be felt at lower speeds as well.
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
