Pad and Rotor Bedding:
Bedding is a "real conditions" heat cycle and the final step in
preparing the pads and rotors for service. All pads, even OE stock
replacement parts, will benefit from a proper bedding cycle. All
rotors, especially cast iron rotors that will be operated at
sustained high temperatures, will provide longer service life and
smoother braking when properly bedded. Bedding can be done either in
the vehicle, or on a special bedding dyno that can realistically
duplicate the torque loads, pressure, and temperature that will be
realized in the vehicle.
Rotor bedding is an essential element to high level performance and
durability. It is most critical with cast iron rotors. Cast iron is
extremely well suited to use as a brake rotor, but it can be
susceptible to thermal stress, distortion, and even cracking if
subjected to rapid changes in temperature when it's new. The cracking
sound that you may hear when pouring a favorite beverage over a glass
of ice is thermal shock. A proper bedding cycle will gradually bring
the rotors up to temperature and then allow them to cool slowly and
completely in order to "season" and relieve any remaining
stresses from the casting and machining processes. With some
compounds, a layer of pad material may also be embedded onto the
rotor face. It is important that this "transfer layer" be
deposited slowly and smoothly. Otherwise, pedal pulsing and
compromised friction values can result.
The bedding process is the final "heat cure" for the pads. This
final bedding cure differs from an oven heat cure in such that the
oven heat cure does not include the pressure, torque, and elevated
surface temperatures that are necessary to properly condition the pad
for service. As it is with the rotors, new pads must be gradually
brought up to temperature and then slowly cooled. If the pads are put
into hard service right from the start, damage from fractures or
accelerated deterioration due to extreme temperature variations
between the surface and the body of the pad can occur. Overall poor
performance with the potential for rotor damage are often the
Once the brake system has been tested and determined safe to operate the
vehicle, follow these steps for bedding of all pad materials and
During the bedding process, a more positive feel from the brakes should
develop. This is an indication that the bed in process is working. If
any level of brake fade is observed during the hard stops, it may be
an indication that the brakes have been more than adequately heated.
Begin cooling the brakes with light driving and without brake contact
- 1. Begin with a series of 8-10 light stops from approximately 30 MPH
down to 15 MPH allowing 20-30 seconds for cooling between each stop.
- 2. Progress to series of 8-10 moderate stops from around 45 MPH down to
30 MPH allowing the 20-30 second cool down period between each stop.
- 3. Proceed with a series of 8-10 hard stops from 55-65 MPH down to 25
MPH allowing 20-30 seconds of cool down time between each stop.
- 4. Drive at a moderate cruising speed, with the least amount of brake
contact possible, until most of the heat has dissipated from the
brakes. Avoid sitting stopped with the brake pedal depressed to hold
the car in place during this time. Park the vehicle and allow the
brakes to cool to ambient air temperature.