Bedding in new rotors

Discussion in 'Modifications & DIY how-to' started by miloman, Oct 17, 2007.

  1. miloman

    miloman Retired Admin

    Just bought a set of Power Slot front rotors from Sakari. I needed to replace my stockers because they are starting to show bad grooves. Anyways, I intend to install them along with the XP10 front pads in the next day or so.

    I was looking over the break-in instructions. They state the standard multiple slow stops followed by a few hard stops. However, they do say 'Avoid excessive or high speed braking until your new system has seated in. This will take approximately 200 to 500 miles'. How important is this? My plan was to install these and use them at Talladega on Sunday. The drive there is close to 100 miles but there's no way I will be able to get close to 500 miles on the car by then. Should I be worried? I don't want to put off the install until after the event because I don't want to run my new pads on grooved rotors.
     
  2. Sparta

    Sparta Active Member

    when i put my rotors on ped just told me to do some hard braking on the highway. I didn't change my pads though so i dunno. Then again I just had cheap ebay rotors
     
    Last edited: Oct 17, 2007
  3. miloman

    miloman Retired Admin

    I might be wrong but I think it might just be something they put in for liability reasons. I figure if you made a mistake during the install, it should surface within 500 miles. You wouldn't want it to surprise you at the track.
     
  4. welery

    welery Member

    I think you'll be fine doing the multiple slow stops and a few hard stops. Remember that the track pads won't be at their best until they have some heat on them.
     
  5. FACE

    FACE Active Member

    I have read that you need to get them up to temp and keep them there with several hard stops to set them in. I think you have to get them to temp and keep them there to cause a chemical reaction to get the first layer off the pads. Check the site of the pads you have! btw have fun at the track man!
     
  6. techlord

    techlord Active Member

    Not sure if the STI is different but today got my XP10's and XP8's and it said to do several medium stops let cool down followed by several hard stops until some fade is felt then to bring to a stop and let cool to ambient temp. I guess I am good to go time will tell.
     
  7. slowwrx

    slowwrx Supporting Member

    All you are really trying to acomplish is to get a nice transfer layer onto the rotor. I wouldn't worry about a specific mileage, just drive on them before you get to the track
     
  8. keeganxt

    keeganxt Active Member

    This is the one I always reference...

    Pad and Rotor Bed-In Theory, Definitions and Procedures:
    Removing the Mystery from Brake Pad Bed-In


    by Matt Weiss of StopTech and James Walker,
    Jr.
    of scR motorsports


    In order for any brake system to work optimally,
    the rotors and pads must be properly bedded-in, period. This process
    can also be called break-in, conditioning, or burnishing, but whatever
    terminology you choose, getting the brakes properly bedded-in and keeping
    them that way is critical to the peak performance of the entire brake
    system.
    However, understanding why the rotors and pads need to be bedded-in
    is just as important as the actual process. If one understands what is
    happening during the bed-in process, they can tailor the process to specific
    pads, rotors, and/or driving conditions. For this reason, we present
    this generic bed-in overview pertaining to all brake systems, but follow
    with links to application-specific bed-in procedures to fit most every
    set of circumstances.


    What is brake pad “bed-in” anyway?



    Simply stated, bed-in is the process of depositing an even layer of brake
    pad material, or transfer layer, on the rubbing surface of the rotor disc.
    That's it. End of discussion. Ok, not really, but although bed-in is quite
    basic in definition, achieving this condition in practice can be quite
    a challenge, and the ramifications of improper or incomplete bed-in can
    be quite a-a-n-n-o-o-y-y-i-i-n-n-g-g.

    Abrasive friction and adherent friction


    There are two basic types of brake pad friction mechanisms: abrasive
    friction
    and adherent friction .
    In general, all pads display a bit of each, with abrasive mechanisms
    dominating the lower temperature ranges while adherent mechanisms come
    more into play as pad temperature increases. Both mechanisms allow
    for friction or the conversion of Kinetic energy to Thermal energy,
    which is the function of a brake system, by the breaking of molecular
    bonds in vastly different ways.
    The abrasive mechanism generates friction or energy conversion by the
    mechanical rubbing of the brake pad material directly on the rotor disc.
    In a crystalline sense, the weaker of the bonds in the two different
    materials is broken. This obviously results in mechanical wear of both
    the pad and the rotor. Consequently, both pads and rotors are replaced
    when they are physically worn to their limit and are too thin to endure
    further service.
    The adherent mechanism is altogether different. In an adherent system,
    a thin layer of brake pad material actually transfers and sticks (adheres)
    on to the rotor face. The layer of pad material, once evenly established
    on the rotor, is what actually rubs on the brake pad. The bonds that
    are broken, for the conversion of Kinetic to Thermal energy, are formed
    instantaneously before being broken again. It is this brake pad-on-transferred
    brake pad material interaction on a molecular level that yields the conversion
    process.
    With the adherent mechanism there is much reduced rotor wear as compared
    to abrasive mechanism, but it's not a free lunch – pads now become the
    primary wear element in the braking system. And even though rotors are
    not mechanically worn down with adherent systems, they still will need
    to be replaced on a regular basis due to cracking reaching a point of
    failure if they are exposed to intense, repetitive thermal cycling. This
    is why race teams throw out rotors that are actually as thick or thicker
    than when they were brand new. It's due to the an adherent brake pad
    transfer layer!


    The all-important transfer layer



    As stated above, the objective of the bed-in process is to deposit an
    even layer of brake pad material, or transfer
    layer
    , on the rubbing surface of the rotor disc. Note the emphasis
    on the word even, as uneven pad deposits on the rotor face are the number
    one, and almost exclusive cause of brake judder or vibration.
    Let's say that again, just so there is no misunderstanding. Uneven pad
    deposits on the rotor face are the number one, and almost exclusive cause
    of brake judder or vibration.
    It only takes a small amount of thickness variation, or TV, in the transfer
    layer (we're only talking a few ten thousandths of an inch here) to initiate
    brake vibration. While the impact of an uneven transfer layer is almost
    imperceptible at first, as the pad starts riding the high and low spots,
    more and more TV will be naturally generated until the vibration is much
    more evident. With prolonged exposure, the high spots can become hot
    spots and can actually change the metallurgy of the rotor in those areas,
    creating “hard” spots in the rotor face that are virtually impossible
    to remove.


    Bedding fundamentals



    In general, bed-in consists of heating a brake system to its adherent
    temperature to allow the formation of a transfer layer. The brake system
    is then allowed to cool without coming to rest, resulting in an even
    transfer layer deposition around the rotor circumference. This procedure
    is typically repeated two or three times in order to ensure that the
    entire rotor face is evenly covered with brake pad material. Sounds easy,
    right? Well, it can be if you have the proper information.
    Because the adherent temperature range for brake pads varies widely
    (typically 100°F-600°F for street pads and 600°F-1400°F
    for race pads), each bed-in needs to be application-specific. One could
    try to generate a one-size-fits-all procedure, but too little heat during
    bed-in keeps the material from transferring to the rotor face while overheating
    the system can generate uneven pad deposits due to the material breaking
    down and splotching (that's a technical term) on to the rotor face.
    In summary, the key to a successful bed-in is to bring the pads up to
    their adherent operating temperature in a controlled manner and keep
    them there long enough to start the pad material transfer process. Different
    brake system designs, pad types, and driving conditions require different
    procedures to successfully accomplish the bed-in. The recommended procedures
    below should provide you with the information you need to select the
    bed-in procedure appropriate for your application.

    StopTech's Recommended Procedure for Bedding-in Stock-sized Brake Systems

    StopTech's Recommended Procedure for Bedding-in Performance Brake Systems

    Bed-In FAQ
     
    Last edited: Oct 17, 2007

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