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So i first bleed my brakes and really botched it, getting brake oil everywhere. I cleaned up, got new pads and wiped the rotors down. I got new brake pads which i the proceeded to bed in. Eventually they stuck well and I declared them ready to go and put my bike away. About 2 weeks later I get it out again, and the brake doesnt stick well, and is squeaking. I sand the brake pad and bed it in again and then braking performance improved. Now i took my bike out and it seemed like the same thing happened.

Is it that the brakes arent fully bed in yet? Why would my braking improve then become worse after I put my brake away?

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    How well did you clean the rotors? Wiping down with a rag probably isn't enough, you'd want to use some kind of solvent/degreaser.
    – Jamie A
    Commented Aug 16, 2017 at 15:49
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    When you bled them are you absolutely positive you got all the air out? Did you create a vacuum and go through all the proper steps? Could be there was air left and it has migrated while being moved/sitting in "storage".
    – Nate W
    Commented Aug 16, 2017 at 18:17
  • Well before i bleed them the handle would squeeze far down. Then after bleeding it seemed like the pressure was fine so Im pretty sure i bleed it well enough.
    – user74671
    Commented Aug 16, 2017 at 21:10
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    Brake pads are often made of porous material and the oil can migrate into it. You'll never fully decontaminate them. Luckily they are cheap.
    – RoboKaren
    Commented Aug 16, 2017 at 22:18
  • 2
    Now you completely understand the evolution of bleed blocks. All without attending Mechanic U.
    – Craig Hicks
    Commented Aug 16, 2017 at 23:10

3 Answers 3

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Place a wooden ruler or a piece of paper folded 8 times instead of disk rotor to check brakes. Then take your rotor and pads and thow them away to get new one.

When oil gets between rotor and pads, your pads get oiled and they will place oil onto new rotor.

Rotor itself can still contain some oil on it after washing, you will not be able to remove it. So old rotor will place oil onto new pads.

That is why you need to replace both.

The other way is to overheat your pads and rotor in open flame for about 10..15 minutes. Open fire will burn oil, but it is dangerous - pads may blow up and rotor may get screwed, so this is "i have no money" way

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Per the comments above, the old rotors you wiped down may be contaminating the new pads or vice versa. Your best bet is to replace both, and wipe down all the other relevant parts (e.g. brake caliper housing) with something like rubbing alcohol before trying to put the new pads and rotors on.

If you're really set on reusing the existing rotors, I'd recommend take them off and wash with hot slightly soapy water until "squeaky" clean, then rinse thoroughly with very hot water. Allow them to dry, then wipe thoroughly with clean paper towel wetted with rubbing alcohol as a final step. Allow to dry again. Do not directly touch the braking surface again after doing this.

I've found rubbing alcohol works well for rotors and the surface of pads because it cuts small amounts of grease nicely (e.g. the tiny bit left over after the above soapy water process), and evaporates very quickly (hence the cold fealing you get when you spill it on your hands), and leaves no residue after evaporating. It's also nice & cheap, and readily available at all pharmacies and most grocery stores.

However, it's not magic: the oil contamination in the porous pads probably can't be reliably cleaned out without BBQ'ing them per filimonic's answer above.

Addendum: If you're REALLY hell bent on keeping the current rotors and the above process doesn't work, you can investigate the method colloquially known as Disco Inferno in which you cover them in rubbing alcohol or some other flammable item that leaves little residue after burning, and light them on fire, burning off the contaminants. Proceed with caution.

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My solution ended up being sanding rotors lightly and cleaning them well wth automotive brake cleaner. For the pads What ended up working was sanding them down well past the pitting that occurred and wiping them off with isopropyl alcohol.

After breaking in the brakes worked much better although not as great as before. New pads (and maybe rotors) may be necessary for a complete fix but for now the brakes are satisfactory

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