"Burnishing" your new brakes. WTF......... Now I've heard it all. (I'm raising the Bullsh!t flag)

[The Evil Twin]

The process you describe in your second paragraph sounds nearly/exactly like me simply driving home while adjusting the gain, and I agree that's pretty much what I do to.

That is not what I am talking about.

My original "bitch" was in regard to videos linked below.

This gentleman, "claims" that we need to to apply the brakes and I quote "30 to 50 times with about 1/2 mile to mile between applications for cool down" (see the 4:36 mark).

I take umbrage with the advice given. Sounds more like bad advice/BS to me.

That is horrible advice in the video. He has probably ruined brakes on people's trailers. Under no circumstances should new brakes get that hot. Never.
I can pull up a half dozen brake manufacturers that specifically say "gentle" brake application and "do not panic stop" on new pads.

 

[JRHill]

I have another problem with this thread and that is: it is said the brake friction material has to be transferred to the drum. Or disks to pucks. Whah, what? On a brake job with new surfaces there absolutely has to be a break-in period. And I don't think burnishing is necessarily the wrong word. But what is getting prepared and transferred in the process? Both the friction material AND the steel be it a drum or a disk go through a 'burnish' if you will. Both well get 'polished' and seated together. There is the brake action.

Yes, there are problems with using the wrong pucks on disk brakes but is it because the wrong materiel is imbedded in the steel disk? No. It's a new surface and you didn't prep the new steel and friction material for a break-in or, Lord forbid, you went out of spec and used the wrong brake material. Your 'burnished' drums and disk aren't going to mate well. You will over heat one or the other.

Consider also a wet brake or clutch, a friction/manual dry clutch, and on and on. EVERYTHING depends on mating materials broken in the correct way per the application.

 

[McMXi]

The process you describe in your second paragraph sounds nearly/exactly like me simply driving home while adjusting the gain, and I agree that's pretty much what I do to.

That is not what I am talking about.

My original "bitch" was in regard to videos linked below.

This gentleman, "claims" that we need to to apply the brakes and I quote "30 to 50 times with about 1/2 mile to mile between applications for cool down" (see the 4:36 mark).

I take umbrage with the advice given. Sounds more like bad advice/BS to me.

I haven't watched the video but from your description it does sound utterly ridiculous. Ultimately, we all need to think for ourselves and make the best choices based on the information available and our own experience with a measure of common sense and science thrown in.

I will say that the brake "feel" seemed to improve as I progressed from the first to the fifth stop using only the brake controller. Placebo effect? Perhaps. As is often the way though, no one was behind me until I started the break-in procedure. People must have though I was nuts!

 

[Tughill Tom]

Enough, just drive it like you'll stole it..... this is gone on way too long. It will stop at some point.
RANT OVER.

 

[dlsmith]

In the ~50 years I've installed new rotors and pads on my vehicles, all I ever did was install them and drive them normally. I always got excellent life out of them.
Maybe the new pads are kinda sissies, and need to be pampered for a while.

 

[NCL4701]

Burnish might not be the best word here.

burnished; burnishing; burnishes
: to make shiny or lustrous especially by rubbing

I think you identified the crux of the issue.

“Burnish” may be the term used by one or more manufacturers so maybe it’s technically the currently correct term or at least a correct term. The procedure it’s describing is nothing new, but I’ve never heard it called “burnishing”. Maybe that’s a regional thing. And while the annotative meaning may be correct, the connotation is too close to “glazing” to not immediately raise BS flags when the word is coming from the mouth of a media influencer who is paid for clicks rather than accuracy.

The reason I began breaking in new brakes in the 70’s was because the first vehicles I worked on and drove belonged to my father. Had I not broken the brakes in after doing a brake job on one of his vehicles, I would have needed his boot surgically removed from my butt. I kept breaking them in because they work better after break in than before.

While I’m not ignorant to the changes in brake pad material over the past few decades, I’ll leave the materials science discussions to the engineers. As long as manufacturers specify it and it keeps working, I’ll keep doing it.

 

[CGMKCM]

I follow this guy on YT and I like how he presents information. Burnishing trailer brakes

 

[McMXi]

Diamond C Trailers has a video regarding the break-in process for trailer brakes. A bit of digging will find other trailer manufacturer videos focused on educating customers about their products rather than trying to make a living off their YouTube videos.

 

[The Evil Twin]

I have another problem with this thread and that is: it is said the brake friction material has to be transferred to the drum. Or disks to pucks. Whah, what? On a brake job with new surfaces there absolutely has to be a break-in period. And I don't think burnishing is necessarily the wrong word. But what is getting prepared and transferred in the process? Both the friction material AND the steel be it a drum or a disk go through a 'burnish' if you will. Both well get 'polished' and seated together. There is the brake action.

Yes, there are problems with using the wrong pucks on disk brakes but is it because the wrong materiel is imbedded in the steel disk? No. It's a new surface and you didn't prep the new steel and friction material for a break-in or, Lord forbid, you went out of spec and used the wrong brake material. Your 'burnished' drums and disk aren't going to mate well. You will over heat one or the other.

Consider also a wet brake or clutch, a friction/manual dry clutch, and on and on. EVERYTHING depends on mating materials broken in the correct way per the application.

I have raced for many many years ans was supported for most of them by a leading brake company. There is absolutely transfer of the friction material (pad or shoe) to the metal used in the rotor/ drum. This is what changed the kinetic energy (rotation) to heat energy (friction). That is what slows you down. You could take a new rotor and a new pad and it will not stop well. Both surfaces are glass smooth. 100% surface contact. Why? Because the friction coefficient of pad on steel is not as high as pad on pad.
Wet brake/ clutch is a totally different animal.

 

[lugbolt]

yeah burnishing is real

the race car has really expensive brakes designed specifically for the purpose I used it for

you MUST burnish them, more or less destroys them if you don't it can get really expensive and could possibly hurt...

on most any street cars it's still a very good idea to do it, they last a lot longer if done properly

 

[jaxs]

And it only works if you have the right oil in crankcase.

 

[lugbolt]

same for belts on some CVT equipped equipment.

There are two main reasons for break in. One, some of the pad (or belt) material needs to impregnate into the metal. That IS normal, you just don't see it unless you're an engineer with some expen$ive microsopic equipment.

Other reason is that the shape of the friction surface and the shape of the part that it runs against (pad and rotor or pad and drum or belt & sheave) is slightly different. one belts, the "VEE" of the belt is slightly different than the angle of the "VEE" in the sheaves. So you have to drive it a certain way, to wear in the belt so that it conforms to the sheave faces at the correct angle. Failure to do so WILL result in an overheated and often failed belt. Similar on brakes. The pads look flat. The rotor looks flat. But in microcopic reality, they are not the same even if everything is new. The caliper pins can let the caliper "rock" a little bit which reduces the amount of contact between the pad and rotor. Over time the pad will wear into that angle. That is part of a break-in process and why they say to do it. Most people don't, and then the small amount of contact between pad and rotor builds up a hot spot on the pad which hurts the material that the pad is made out of.

Lastly the material that the rotor or drum is made out of is designed to be heat treated, and that is done by proper burnishing. We know how brakes work. They convert kinetic energy to heat. That heat needs to be dealt with, and different places do it differently. On the race car, they use solid rotors which are irregularly shaped (like a lot of sport bikes) and the irregular shape dissipates the heat into the air, instead of into the caliper. The calipers are aluminum and will soak up a lot of heat if the rotor can't get rid of it, and that will destroy the caliper pistons and o-rings.