Brake Pad Wear Indicator - E-Class W212

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by Ozboy, May 11, 2017.

  1. Ozboy

    Ozboy Member

    Messages:
    53
    Joined:
    Mar 22, 2017
    Car:
    W213
    The 'Check Brake Pad Wear' warning light on my 2013 e-class illuminated for the first time today and I am wondering what percentage are the pads worn when this light comes on?

    Reason for asking this is that my car is due to be part exchanged in a month and I am relunctant to change the brake pads unless it's essential to do so. I do very low mileage, 17,500 miles in 44 months, and not expecting to do more than 400 miles in the remainining time. I am hoping the pads will be okay (safe) during this period.

    Thanks
     
  2. supermonkeyman

    supermonkeyman Hardcore MB Enthusiast

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    Joined:
    Nov 16, 2014
    Car:
    E250 coupe
    They'll be fine.

    My light has been on for approx 3 weeks and I've done over 1000 miles.
     
  3. cctesta

    cctesta Active Member

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    Oct 13, 2013
    Location:
    Bristol
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    E Class Cabriolet
    Mine came on today!
     
  4. Steveml63

    Steveml63 Hardcore MB Enthusiast

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    Hi,
    My advice is to visually check the pads on both sides of the car with a torch.
    There is only one sensor per axle and we recently found that the rear side without a sensor was more worn than the other side - so the warning did not come up on the dash and caused a bit of damage to the disc (which was corrected by having it refaced)
    Luckily, I was only a few miles from the garage when the brakes made a graunching noise!
    Cheers
    Steve
     
  5. OP
    OP
    Ozboy

    Ozboy Member

    Messages:
    53
    Joined:
    Mar 22, 2017
    Car:
    W213
    I had a a quick look through the spokes of the wheel and the rear looks more worn than the front. I reckon there is around 4mm left in the front and around 2-3mm in the back. few questions:

    Do the inner pads wear at the same rate as the outside?
    How think is a new brake pad?
    Is the rate of wear linea?

    Thanks
     
  6. MancMike

    MancMike Hardcore MB Enthusiast

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    Location:
    Manchester
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    The sensor goes into a hole in the pad, and there's loads of pad left through the width of the sensor and beyond. Honestly you've got thousands of miles left before you get down to the backing plate.

    Even then you can still brake safely, it'll just make a grinding noise and ruin your disk.

    Do the inner pads wear at the same rate as the outside?
    Not exactly, but almost. There's usually a bit of a difference. The bigger concern is that there's normally only a wear sensor per axle. So one at the front right, one at the rear left, or vice versa. So you'd want to be worried the front left isn't severely more worn than the front right. (drivers side normally wears slightly faster than the passenger side).


    How think is a new brake pad?
    The "meat" on it is about 20mm.

    Is the rate of wear linea?
    The material is the same from the backing plate outwards, so I'd guess so. Caveat, some pads have a coating on the new surface that's more abrasive, and causes "bedding in" to occur more rapidly, so that probably 0.2~0.5mm is kind of sacrificial.


    See here: The warning is triggered as soon as the disk touches the electrode of the sensor, but there's plenty of meat around it through the thickness of the sensor and slightly beyond.
    [​IMG]
     
    Last edited: May 12, 2017
  7. OP
    OP
    Ozboy

    Ozboy Member

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    Car:
    W213
    Thanks Mike, that makes a lot of sense.
     
  8. OneForTheRoad

    OneForTheRoad Hardcore MB Enthusiast

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    dont brake . :bannana:
     

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