Glazed pads/rotors

[bike_commuter]

Hi folks,

So, I'm new to disc brakes and didn't get the memo about "burning" them in. I've gone about 400+ miles of city riding now and my brakes have been screeching quite a lot. Took the pads off today and they look pretty "glazed."

What I want to know is: has anyone had luck sanding the pads/rotors and cleaning them or do I really need to buy new pads? I keep coming across conflicting opinions elsewhere on the internet. It would be great to hear about some of your experiences.

Thanks!

[bobtravers]

Sand them a bit with 120 grit sand paper, so you can remove glaze on it!!!

[GeorgeET]

Do not have discs on my bike, but my motorcycle does. On motorcycle couple fast hard stops would break them in and also clear the glaze.

You can also clean them with sandpaper but on a very flat surface like glass plate or a machined steel plate. Marble counter top when the wife is out. :-)) You can go with 80 grit.Tape it down and do figure 8 with the pads . Than clean the discs and pads off with brake cleaning solvent available at at automotive shops. Be careful around paint with it. Use in ventilated space do not smoke. Read label. You can also clean all the disc holes if your disc has them with q tips and solvent. Do nor drag the brakes.

[JonB]

It is entierly possible you've more than just glazed them, you may have contaminated pads.

Best way to find out is to sand the pads back as said, and clean the rotor. The method I use sounds drastic, but works EVERY time (and is fun ). Remove the rotor from the hub and place it on the ground outside well away from everything and preferably on concrete/stone. carefully pour methylated spirit onto the braking surface (you don't need too much, just enough to soak the braking surface). Quickly strike a match and ignite it. Then once it's gone out, carefully flip (it WILL be hot) and do the other side. try and avoid getting meth on the spider, it's unnecessary and may warp or discolour the rotor. Re-install the rotor when it's cooled (don't try and speed up the process, let it cool on its own or you may warp it).

Sounds extreme, but I've tried every other method and this is the only sure-fire way of cleaning it.

If it comes back within a ride or two, you have contaminated pads. Bin them, you can't save them (you'll have to repeat cleaning the rotor before you put a new set of pads in). Pads may go bright and shiny through use (this is normal). However if there is a deep colour in the shine or a dark shiny stripe, that's contamination, and normally associated with a noticeable loss in power from new.

If you are dragging your brakes because they aren't slowing you down, check the pads for contamination. If you can't find the above, try getting bigger rotors as these reduce glazing. Glazing is when the pad surface melts because there's too much heat going through them. Contamination is when you get oil and cr@p on the pads (which acts as a lubricant); telling the difference is hard though, as both make the brakes squeal, but one *should* go away after a clean and sanding, the other will come back quickly and is irreparable.

Hope that all makes sense, if you're still unsure then us know, we'll try and explain it better.


EDIT: I wouldn't use Motorbike disc cleaner on MTB brakes. These contain various solvents and stuff that can contaminate brake pads (certainly don't spray on pads!). On motorbikes this is not an issue, as they get hot enough to burn it off VERY quickly and thus do not cause contamination. MTB brakes do not generate that kind of heat (and if they do, the pads can't take it anyway), so it is not really suitable.

[GeorgeET]

EDIT: I wouldn't use Motorbike disc cleaner on MTB brakes. These contain various solvents and stuff that can contaminate brake pads (certainly don't spray on pads!). On motorbikes this is not an issue, as they get hot enough to burn it off VERY quickly and thus do not cause contamination. MTB brakes do not generate that kind of heat (and if they do, the pads can't take it anyway), so it is not really suitable.
^^^^^^^^^^^^^^

Not sure who wrote the edit???

The brake cleaner is a highly evaporative fluid as no brakes can have residue on them.

However the bonding on bicycle brakes may be different than motorcycle or car. So contacting the manufacturer to be sure is a good idea, If its a save or throw away than a hail Mary pass with brake cleaning fluid is worth a try. Perhaps with a clean tooth brush.

As per the flame method not on my block.:-))