"Bedding in" new brake pads

[alibaba]

2009 M 696 - breaking new ground for this old dinosaur - never had these new fangled disc brakes before.   I just replaced front brake pads - Ferodo Platinum (not sintered or racing pads).  And, I just re-read 2  excellent tech articles on bedding in new pads.  I did not need to replace the discs.  I understand now both 'abrasive friction' and 'adherent friction'.  The problem with both articles is that they assumed the discs were being replaced also.  But since my discs already have the 'deposit' on them, I really only need to 'mature' my pads.  Does anyone know the correct procedure for maturing or cooking the pads to bed them in since the discs have not been replaced?  I assume just follow the same procedure as if the rotors were new?

[ducpainter]

When you change pad material you should clean the rotors and treat them as new from my understanding.

[Howie]

Scothbrite pads and brake cleaner should do the task.  On used rotors I like putting a light chamfer on the top, bottom and leading edge of the pad.  You might get away with not cleaning first with HH semi metallic since they are more abrasive, emphasis on might. 

[the_Journeyman]

Good responses.  Then just follow the typical bedding in advice. 

JM

[manwithgun]

Scothbrite pads and brake cleaner should do the task.  On used rotors I like putting a light chamfer on the top, bottom and leading edge of the pad.  You might get away with not cleaning first with HH semi metallic since they are more abrasive, emphasis on might. 

I'll even go as far as using a worn 120 grit flap disc on an angle grinder or just emery cloth if doing it by hand.  It does make a difference what compound you are changing to as the new pad material must be able to embed itself into the rotor surface.  For example, in the Ferodo line-up, if going from a CP1 carbon/ceramic to the XRAC metallic,  the XRAC is abrasive enough to cut through the old compound.  If it were the other way around,  XRAC to CP1,  you would never get proper braking performance until the rotor surface were refreshed and the new, less aggressive compound were able to embed into the rotor.  That's been my experience anyways.  And +1 on the chamfering.  Not only does this make wheel changes easier (bottom chamfer), but I believe that a square leading edge can induce more initial bite which is not desirable in performance braking, kinda the reason 4-pad calipers are not all the rage anymore as they have more leading edges and that initial bite is a bit more aggressive.  A Ferodo rep I spoke with explained it as their "wedging" theory. 

[alibaba]

Interesting replies all of which instruct me to remove the layer from the disc that in fact increases braking forces and start the process all over again. No one comments on the correct procedure of braking events to bed in the pads.

"There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction."

" ....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."

"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."

[ducpainter]

You remove the old layer and add a fresh one. There are instructions online on how to do this.

If you had replaced the pads with the exact same compound pads that step would be unnecessary.

[Howie]

http://www.braketech.com/index.php?option=com_content&view=article&id=54:racing-brake-pad--bed-in-procedures&catid=17:tech-talk&Itemid=69
is a typical procedure.  Never done it, I live in NYC, so, for me this is just not realistic.  IMO, the biggest concern is sufficient heat, but not too much.  Light braking on new pads can cause too much heat as well as overly aggressive stopping.  I just brake normally until broken in.  Works good enough for me, YRMV.  

[ducpainter]

http://www.braketech.com/index.php?option=com_content&view=article&id=54:racing-brake-pad--bed-in-procedures&catid=17:tech-talk&Itemid=69
is a typical procedure.  Never done it, I live in NYC, so, for me this is just not realistic.  IMO, the biggest concern is sufficient heat, but not too much.  Light braking on new pads can cause too much heat as well as overly aggressive stopping.  I just brake normally until broken in.  Works good enough for me, YRMV.  

I've done it and it works fine. It's easy to find a stretch of road here to accomplish that method. The important thing is to not use the front brake again until things have completely cooled.