Contaminated brake rotor

Discussion in 'Trials' started by Buschog, Mar 28, 2018.

  1. Buschog

    Buschog Been here awhile

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    I cleaned my chain a few weeks ago, the lazy way. I didn't remove the chain, I just blasted it with brake cleaner while it was on the bike. I must have gotten some schmoo on the rotor.

    I rode the bike around the block afterwards and had very soft rear brake. Initially I thought it was probably just wet, so I rode a little with my foot on the rear brake to dry it out. The brake never got better, and when I finally stopped it was smoking a little.

    I ordered and have received new pads. Should I replace the rotor as well? Or can I just soak it in concentrated degreaser and scrub it with scotchbrite?

    I don't want to contaminate brand new pads
    #1
  2. heffergm

    heffergm Long timer

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    Ok, so, here are my 2 cents:

    If you don't get the rotor completely free of whatever was on it, the pads are going to be trash the second you put them on. If you're confident you can decontaminate the rotor, go for it. However, in my experience with pads and rotors, it is possible to end up with a rotor that you can't get whatever the hell was on it off, regardless of how much brake cleaner you hammer it with.

    I guess what I'd say is, give the rotor a good clean, and go for it with the new pads. If you find that things still aren't working right, don't keep trying to clean up the rotor. Trash it and replace the pads (again) and the rotor.
    #2
  3. Ymirtrials

    Ymirtrials Been here awhile

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    Any time I get brake fluid on a rotor I’ve used a non chlorinated brakecleen from CRC with good results, spray it on and wipe it off done.
    #3
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  4. jonnyc21

    jonnyc21 Trials Ninja

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    I have also use the CRC cleaner and fresh towels (role style shop rags) been able clean well and use new pads only. If I ever get the same results after cleaning as indicated by heffergm I will replace both.
    #4
  5. lineaway

    lineaway Long timer

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    Remember to do the water trick.
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  6. Bronco638

    Bronco638 Nobody Home

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    I've never had an issue cleaning a rotor with brake cleaner. I always like to burnish them a little with some fine wet/dry sandpaper (~1500 grit). As Line mentioned above (^^^), after cleaning the rotor and installing new pads, ride around and drag the rear brake until the pads & rotor get (really) hot. Then, dump cold water on them. If you don't see steam rising off the rotor & caliper, it wasn't hot enough. Now, you're good to go.
    #6
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  7. motobene

    motobene Motoing for 46 years

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    Righto everyone!

    To add to.... Brake pads are very porous, but stainless steel rotors are not. Rotors are easy to clean.

    Ditto on sanding rotors. I use 80 grit.

    Seasoning brakes is dragging to heat pads and rotor such that the rotor sizzles when quenched with lots of water. Usually takes about 20 seconds of dragging to heat up that much. Repeat about 4 times. Brakes should get stronger each time.

    You can recover fouled cleaned brakes with seasoning, IF they are not soaked through but just 'speckle contaminated.'
    #7
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  8. LemmeTry

    LemmeTry Over-thinker...

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    Throw the rotor and pads in the oven at 250F for an hour. Let them naturally cool off, and then once installed do the steam clean as outlined above a time or two.

    This has worked great for me in the past.
    #8
  9. Ymirtrials

    Ymirtrials Been here awhile

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    Oh, not too sure if the Better Half would be too keen on me putting ‘dirty bike parts’ in HER oven.... just saying...:D
    #9
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  10. RimBenty

    RimBenty Bender of Rims

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    Go to Goodwill or a thrift store and buy a toaster oven for the garage or shop.
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  11. Buschog

    Buschog Been here awhile

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    Thanks everybody. Guess the clean, install, heat & steam is the plan for tomorrow night.
    #11
  12. motobene

    motobene Motoing for 46 years

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    I have recovered some fork-oil-fouled pads by heating them with a propane/MAPP gas torch in pulses. Toast until oil oozes out and starts to burn. Let cool a bit and repeat until nothing comes out.

    How much is too much heat? That requires judgement.

    Will the pads come back 100%? Usually they won't come back all the way so a set of new Galfer red pads gets ordered. If there is ANY oil left deep in the pads it will migrate out by capillary action and once again rob the braking power. Just a matter of time.

    Removing the rotor is risky. Rotor retention screws typically are assembled with Locktite but no grease. They can corrode and freeze up, then will twist off. In new-bike setup I remove rotor screws and do a combo of grease and blue Locktite on the threads. On well-used bikes I don't try to remove them unless I absolutely have to, such as to replace a rotor.
    #12
  13. LemmeTry

    LemmeTry Over-thinker...

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    Just do it when she's not looking :p
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  14. LemmeTry

    LemmeTry Over-thinker...

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    Also, if your rotor is slotted, you have to pay attention to cleaning the slots out because grease/grime can build up in there and then continually ooze back out if not completely removed. Don't ask me how I know... :lol3

    That's one advantage of sticking it in the oven - all that crud gets baked off.
    #14
  15. Ymirtrials

    Ymirtrials Been here awhile

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    Locktite and grease? Please explain how this would function...Locktite on the end then grease on the the remaining threads so they connot seize?
    #15
  16. heffergm

    heffergm Long timer

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    I don't get that either, but fwiw, on my last couple new bikes, I found all the rotor bolts we already loctited.
    #16
  17. motobene

    motobene Motoing for 46 years

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    Certainly! The combo is beyond 2D thinking. I do some things that gobsmack, but they are well thought and and very well tested.

    All my threads get grease. Contrary to intuition, grease helps prevent loosening from corrosion and sticking from corrosion (it's complicated).

    In those very few cases like brake-rotor screws and the kick start retaining screw and that one pesky muffler screw that loves to loosen, they get the baseline grease but also a drop of Locktite.

    Locktite kicks off in pressure interfaces deprived of air. That includes threads full of grease. Grease for corrosion resistance and better tightening feel, and Locktite for added 'prevailing torque' effect.

    Dry fasteners are a pain. Locktite on dry dry fasteners can be an invitation to future very-stuck fasteners (think older Montesa 4RTs). Corrosion, plus the Locktite fossilizing to bone.

    You can have your cake and eat it too! :pynd
    #17
  18. Ymirtrials

    Ymirtrials Been here awhile

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    Hmmm, food for thought thanks. I grease all fasteners as well before reassembly.
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  19. heffergm

    heffergm Long timer

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    I just get grease on all of them by accident...
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  20. Buschog

    Buschog Been here awhile

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    Rotor cleaned, and pads replaced. 3 heat/quench cycles.

    No time to ride afterwards. Getting the camper setup for a weekend at Moonrocks near Reno. Looking forward to it. I have ridden more than in the street at home in months.
    #20