FAQ #4: What precautions must be taken when switching from street pads to track pads?
If you are changing pad compounds, such switching from street pads to track pads, you need to remove all of the material on the rotor and replace it with a fresh transfer layer of material from the new pads. To be honest, rotors do not like to have different compounds used on them, and virtually all rotor and pad manufacturers recommend that you do not swap pad compounds on the same rotors. The reality is, however, that most customers don't have two complete sets of rotors, so here are our recommendation for managing compounds between track and street use. Note that diligent bedding-in is the key.
When switching from street pads to track pads, one needs to make sure that as much of the street compound is removed from the rotor as possible before aggressive track use. The risk here is that any street pad material remaining on the rotor will be subject to deterioration from overheating. This can ultimately cause severe vibrations due to uneven pad deposits (a smearing of the street pad material on the rotor face).
A common method for removing street pad material is to install the track pad prior to driving to the event. Because most track pads operate in an abrasive mode during regular street operation, driving them to the track will wear off any existing brake pad material en route. You will know when the street pad material is gone by the squealing noises coming from your brakes after a short while…
FAQ #5: What precautions must be taken when switching from track pads to street pads?
Many people make the mistake of thinking that because they have a used set of pads in the past that the system does not need re-bedding when they are re-installed. Remember, the same material must be adhered to the rotor as the pad running against it for effective braking. Race pad material must be removed prior to street use.
Since you're not as likely to overheat the rotors on the street after a track event, over time the street pads will remove and replace the track pad material on the rotors naturally. However, the best solution where street pads are being put back into service after a track day is to follow the original bed-in procedure for the street pads after the swap.
FAQ #6: Do I need to bed-in new pads if I do not change pad compounds?
Although you do not typically need to establish a fresh transfer layer for a new set of pads if they are of the same compound as the previous set of pads, there is still a need to mechanically seat the pad face to the rotor face. Because the pad and rotor wear together as a matched set, by the end of a pad's useful life the rotor face is usually not completely flat. Consequently, when installing new pads on a used rotor, there is a small window of time in which the new pads will rapidly wear down against the peaks and valleys of the existing rotor face. This process of re-establishing the wear interface is often referred to as burnishing.
At the same time, new pads may need to be heated and cooled a few times before hard use in order to burn off all of the residual manufacturing resins and excess binding agents present in the pad compound. This process ensures that the exaggerated fade present in new pads (the “green” fade) is not experienced at speed when they are needed most. Unfortunately, this process of heating and cooling the pads is commonly referred to as bedding-in even though it has nothing to do with establishing a transfer layer. Gassing-out is a more appropriate term for this process.
So, while establishing a transfer layer is not necessary with new pads of the same compound, performing a bed-in procedure will serve to establish the wear interface as well as to expose the pads to their green fade in a controlled environment. For this reason, we recommend performing a formal bed-in any time rotors, pads, or both are changed, regardless of pad compound or rotor manufacturer.
