Bedding in pads

[Guest]

Hey all. I just put new semi-sintered (because I can't stand organics) pads on my 81 gs650gl. I also flushed the fluid and replaced the brake line (mmm stainless). (The pads are EBC FA-65v pads if anyone wants to get some.)

I was going to go out and bed them in this afternoon, but after a bit of reading, I'm seeing two different ideas.
What I'm used to is: go for a drive on a country road and brake from 45 to 15 5 times, then brake from 60 to 20 5-8 times, then let the brakes cool off and avoid coming to a complete stop.

What the pads packaging says is:
"Ride carefully in town for 250 miles and your pads will be bed-in correctly" .... That contradicts everything I know about braking. But everything I know about braking is based on cast-iron rotors on cars with power brakes, so... Yeah.

What gives? Has anybody tried both ways?

As I understand it, the purpose of the bed-in procedure is the following things:
Establish an even layer of friction material on the rotor.
Cook out any remaining semi-volatile chemicals to fully dry the pad.
Mate the two surfaces together.

Is this difference because our bikes don't (do they?) have cast rotors and the rotors are much softer? That's the only thing I can think of.

Cheers

[WilliamGLX81]

Anybody? 10chars

[Agemax]

just ride and use them as normal. just dont expect full on stoppie power for a while until they have bedded in properly. just allow extra stopping distance until they feel like they are working upto full potential

[TooManyToys]

Burnishing, or “bedding in” of brakes is compound and manufacturer specific, although once you get to specific point it doesn’t matter how you got there.

There are three aspects of burnishing. The first is the smoothing of both the rotor/ drum and friction material surfaces. This is needed to prevent the wearing away of the immediate surfaces in the braking event. I’ll get back to this.

The second is the conversion of the rubbing layer of the friction material to a carbon material. It’s been theorized on the molecular level the temperature at the rubbing interface gets into the thousands of degrees. This is confirmed when we looked at this rubbing interface under an SEM and found it to be mostly carbon. The organic present in every type of material, with the exception of a full sintered metallic, develops into a carbon product.

The third is the friction material (carbon) transferring a very thin level of itself onto the rotor or drum opposing surface. This layer is needed during cohesive friction when the highest value of stopping power is achieved.

Getting back to the first aspect, smooth surfaces: This cannot be fully realized unless both surfaces are polished out so there is no (minimal) abrasive wear to remove the transfer layer and friction material’s carbonized surfaces.

Another components in the mix and why I said its compound and manufacturer specific is how much organic is there to carbonize and what has the manufacturer done during processing of the parts. A manufacturer can go through a post bake cycle, putting the heat pressed parts into an oven for s specific time and temperature, they can go through a scorch processing heating what will be the rubbing surface with a flame, or they can use a laser to carbonized that same surface. Or they go real cheap and tell the consumer to run through a series of steps to heat the friction up to a carbonizing temperate while also polishing out the surfaces.

There is really no simple answer to all brake material with the exception of saying to make sure the rotor/drum surface has about a 50 micro inch surface that will polish out quickly while also polishing out the friction materials surface and to follow what the manufacturer states in their literature as they know the compound and processing.

An organic matrix will rely on cohesive friction during most of its temperature range and until all surfaces are polished, carbonized and transferred will not obtain full frictional ability. Depending on the quality of the compound it may develop temperature fade all the time (remember that the carbon layer is very thin at the rubbing surface) or only during the initial stages and be fine after some thermal experience turning the friction material bed under the rubbing surface into more of a “B” staged carbon product, “boiling off the organics” if you will. During this “B” staging is when you see a glazed surface which contrary to belief will just wear away in short time.

Metallic reinforced or sintered compounds tend to have low friction when they are cool as they are relying on abrasive friction at this temperature range, but develop higher friction at elevated temps when the transfer layer is stabilized.

What’s known as “ceramic” refers to the fiber reinforcement, not all of the other 12 to 20 ingredients in a friction material compound. It can be either an organic or more towards a semi-met in the other ingredients and it’s performance / traits can go either way.