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Brake Deglazing?

Discussion in 'Downhill & Freeride' started by Inclag, May 11, 2019.

  1. Inclag

    Inclag Turbo Monkey

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    Pretty simple really. Anyone have any good methods to deglaze a brake? Pretty frustrating when a pad and rotor have 95% life but take 20 ft to stop you when just rolling along on flat pavement.
     

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  2. johnbryanpeters

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    If it's glazing, sandpaper. If it's contamination with oil, grease, or brake fluid, toss the pads.
     
  3. Jm_

    Jm_ Turbo Monkey

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    For contamination, remove pads, clean with alcohol, bake at 400F for 15-20 minutes (be sure to wipe down the rotors too with alcohol). This has a 100% success rate for me, which is something I struggled with for years (contaminated pads and how to clean without giving up).
     
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  4. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    I've discussed this before in the brake thread, if you're riding DH (and/or are a heavier rider), this is what sintered pads do. You can try sandpaper but the heat damage (it's a heat hardening/aging rather than just surface glazing in my experience) usually goes right through the sintered material.

    The long-term solutions are to either switch to non-sintered pads, or if sintered pads are absolutely necessary, make sure they are the Shimano heatsink ones. No other brand heatsink pad is constructed correctly in my experience. They will still deteriorate with heat exposure but at a slower rate.

    However, on johnbryanpeters' note, if you're running Shimano brakes it's also common for them (especially when left unridden for some time) to weep oil onto the pads, in which case the solution is the same as above - replace the pads.

    Finally, there's another separate problem that happens with older rotors - the braking track wears faster in the center (where ventilated) leaving a concave profile. When new pads are installed, it takes some time for them to match the concave rotor profile - which results in (particularly, and IME only in the case of sintered metal pads) a portion of the pad surface being exposed to higher localised temperatures, which results in glazing (or permanent heat damage to the pad) occurring much faster than if the surfaces were mated in less time. Obviously this is logically a far bigger problem with sintered metal pads because the slower wear rate means far more braking is done before the pad reaches full surface contact.
     
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  5. Westy

    Westy the teste

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    Under medium heat add wine or stock. Stir while reducing.
     
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  6. johnbryanpeters

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    Finish with tender application of angle grinder.
     
  7. englertracing

    englertracing Monkey

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    Pea on them...
    learn how over on facial abuse dot com
    jk....

    if contaminated put them in the trash or throw them into your neighbors front yard
    if the rotors are concave throw it like Zena the princess warrior, preferably at the dude who designed the vents because he sucks ballz or you your using a pad that is not the correct height for the rotor, they are supposed to be designed with the holes evenly distributed across the rotor so they wear evenly.
    B12 carburetor cleaner
    pull the pads off spray em down, lap them wet with 280 to 320 grit sand paper on a granite stone or plate glass, wash them with water after that.
    for the rotor maroon scotch bright with b12 fer dayz. then clean it up more with ragz n moar b12.

    re bed..... with a big ass paved hill and bursts of braking with cooling between.

    then visit facial abuse
     
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  8. Katz

    Katz Monkey

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    I've used a blow torch in the past (with success, I might add) when I was in hurry, but that sounds like a more sensible approach.

    My ultimate solution was to ditch Shimano brakes entirely, so I don't have to bleed the damned brakes before every ride.
     
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  9. Jm_

    Jm_ Turbo Monkey

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    Well, the other solution is to ride all of your bikes every day and not let them sit for 2 weeks. Gets kind of hard to do after a while though.
     
  10. jonKranked

    jonKranked Press Button, Receive Stupid

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    In a pinch I've rubbed brake pads against a very flat rock mid ride when this has happened. It works well enough to not die the remainder of the ride, then attend to a proper fix post ride.
     
  11. Jm_

    Jm_ Turbo Monkey

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    Avid mechs used to glaze over bad for me on big descents. Braking and deathgrip were inversely proportional.
     
  12. Westy

    Westy the teste

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    Smearing mud on the rotors can also help in a pinch, just find proper mineral mud and not the loamy organic stuff.
     
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  13. TrumbullHucker

    TrumbullHucker trumbullruxer

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    Bake em while you visit the shed
     
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  14. maxyedor

    maxyedor <b>TOOL PRO</b>

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    I sand the pads lightly on a flat surface, then soak in alcohol, heat up with a torch or in the toaster over, lightly sand the rotor and put it all back together. Seems to work.

    QUOTE="Katz, post: 4344787, member: 71870"]I've used a blow torch in the past (with success, I might add) when I was in hurry, but that sounds like a more sensible approach.

    My ultimate solution was to ditch Shimano brakes entirely, so I don't have to bleed the damned brakes before every ride.[/QUOTE]

    The torch is generally my go to as well, but you gotta be careful, I exploded all the sintered material off my Magura pads once. Hot flying brake pad material is uncomfortable when it hits your arm.
     
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  15. jeremy_2640

    jeremy_2640 Chimp

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    I use one of these every now and again -

    Very little effort and with a new consumable it doesn't contaminate the rotor.

    Plus they look new after it..
     
  16. Sandwich

    Sandwich Pig my fish!
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    I remember when you poured Dr Pepper on your Codes to get them to suck less
     
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  17. 6thElement

    6thElement Schrodinger's Immigrant

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    The only way to make original Codes suck less was to sell them.
     
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  18. sundaydoug

    sundaydoug Monkey

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    As a long-time Shimano brake user (Udi's mention of fluid seepage onto pads after long periods of non-use) I've done the following once or twice per season with success:

    Remove rotors and pads
    Spray light application of brake cleaner to rotors and pads
    Clean all thoroughly with a clean paper towel
    Lightly sand surfaces of pads and rotors
    Repeat brake cleaner application and clean w/paper towel
    Reinstall
    Finish with proper bed-in procedure
    Go ride
     
  19. mdc

    mdc Monkey

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    Rubbing alcohol and a Scotch Bright pad for the rotors. Sanding and a butane torch for the pads. Or just buy new pads and avoid a big hassle....
     
  20. Bike078

    Bike078 Monkey

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    Same here. Sand paper and alcohol on rotors and pads. Hold the pads over a gas stove flame if contaminated, clean again with alcohol then re-install.
     
  21. JustMtnB44

    JustMtnB44 Monkey

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    My Zee brakes have been terrible about this since the get go. The front has never had the power I think it should. It's definitely not a bleed issue, the lever feel fine. I recently bought new pads and will sand and clean the rotors. I hope it helps because who doesn't love their first few DH runs of the day to have 50% or less braking power?
     
  22. jonKranked

    jonKranked Press Button, Receive Stupid

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    braking only slows you down.
     
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  23. Sandwich

    Sandwich Pig my fish!
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    have you tried connecting three different levers, two pad compounds, and replacement pistons from thailand?
     
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  24. StiHacka

    StiHacka Compensating for something

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    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    Shimano calipers suck.
     
  25. Inclag

    Inclag Turbo Monkey

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    Not always. My calipers are rock solid. It's the levers on my bike that are all wonky. Not sure of it is the piston seals or separator/diaphragm unit on my Zee levers or both.

    Also can anyone actually point out where these pressure equalizer relief valves are on Shimano brakes?
     
  26. TrumbullHucker

    TrumbullHucker trumbullruxer

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    I am trying SRAM brakes this year, after years of Zees. And so far I am happy.
    Even after good bleeds with the Shimanos I would experience lever-to-bar scares and then it would suddenly pump back up to normal.
    I know this does not help you one bit, but I just had to chime in to a Volta fans thread

    Edit: the way I got my Zees to actually bite my 203mm front and 180mm rear was baking them, then using automotive brake cleaner on the rotors ( careful, it will kill paint )
    I also bought these pads https://www.lordgun.com/alligator-turbo-shimano-saint-zee-semi-metallic-disc-brake-pads-1 before going to whistler for a week, and they performed great the whole week.
     
    #26 -   May 21, 2019
    Last edited: May 21, 2019
  27. ZHendo

    ZHendo Turbo Monkey

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    There are so many good brake options out there now, I'm honestly not sure why people continue to buy Shimano brakes aftermarket with the weepy pistons contaminating pads and the dangerously inconsistent lever bite point. My TRP Quadiems are a frickin dream - enough power for DH, amazing modulation, Shimano-like bleed process, and Shimano pad/oil compatibility...but best of all, they have never needed a bleed and the lever feel hasn't changed even once while riding.

    I listened to a podcast or something one time where a WC mechanic was talking about how soapy water with Dawn dish soap will clean pads and rotors beautifully and snap the brakes up really well. Tried it, and he was right - seems like the effect is basically a more aggressive alternative to alcohol. Might be worth a shot.
     
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  28. Jm_

    Jm_ Turbo Monkey

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    Well, how old are your TRPs?
     
  29. ZHendo

    ZHendo Turbo Monkey

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    About a year, but they see a ton of trail time since I'm a volunteer instructor with Evergreen during the warmer months and ride a lot year round. My Sentinel came with Codes which people seem to love, and I did too at first, but they wouldn't hold a solid bleed for more than a month or so before they'd start pumping up quite a bit. The TRPs needed one good bleed off the bat (and not gnarly DOT fluid). Plus, they were just over half the price of a new set of Codes.

    The tradeoff for the reliability and modulation is the peak power, which is less than Codes and substantially than Saints, but they're fine for me.
     
  30. jonKranked

    jonKranked Press Button, Receive Stupid

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    i think i heard this too. i'm less hesitant to try it now that someone else guinea pigged the method :D
     
  31. sundaydoug

    sundaydoug Monkey

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    I thought the same thing when I rode the TRP Quadiem G-spec. They were some of the most consistent-feeling brakes I've ridden, but after years on Saint/Zee/XT the power just wasn't there.
     
  32. Katz

    Katz Monkey

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    With TRP-branded metallic pads fully bedded in, I thought my Quadiems are about equal to my old M820. But I was running the Saint calipers paired with non-Servowave levers, which I'd guess reduced outright wheel-locking power to some extent.

    I actually prefer softer initial bite of stock semi-metallic pads for everyday use, but I drop metallic pads in the front caliper when I go to a bike park.

    I agree them brakes are very consistent and reliable. I got mine used (with reportedly 400 miles on) last October. My bike rides have been somewhat uneventful since, distinctly lacking bonus adrenaline rush induced by familiar Shimano features such as Random variable bite point.
     
  33. ZHendo

    ZHendo Turbo Monkey

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    Not to mention the self-contaminating pad feature(TM) due to weepy pistons - never wear out pads again, because they won't make it past half life without getting contaminated!

    The difference between the stock semi-metallic and upgraded metallic pads was huge in my experience. It's awesome that Shimano non-finned pads fit - can get metallic Zee/Saint pads for $14 per set in some places, and it makes the TRPs much closer to other market leaders in terms of power.

    I spent the weekend shuttling up in northern WA testing some yet-to-be-opened trails, and they were steep as all hell. Roughly 2200' vertical drop per run over the course of a 7-8 minute run if you were fully pinned, and both my buddy and I were running the TRPs (mine G-Spec, his standard). No variations in bite point whatsoever, no changes in brake feel, no signs of power loss. I'm trying Curas on my new hardtail, really hoping they can match the TRP reliability while being a lighter option.
     
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  34. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Completely invalidates the comparison, hence your result.
     
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  35. Katz

    Katz Monkey

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    Right you are. The point I was trying to convey was there's noticeable difference between TRP's stock semi-metallic and optional sintered metallic pads, and the Quadiem has enough clamping force to lock up a wheel with ease with right pads. The M820 comes stock with sintered pads IIRC - optional sintered pads should be used on the Quadiem for a fair comparison. I figured I'd add this fact to the conversation since there was no mention of it. That's all.

    Here's a picture of M785 lever and M9000 lever overlaid. I'd have taken a M820 lever apart if I still had one, unfortunately I don't.
    IMG_2395.JPG

    The M9k lever has about 6:1 leverage ratio, pulling it with one finger at the very end. The M785 seems to have potential to generate about 5% more maximum leverage (my best guess - my digital caliper is dead). I say "potential" since I don't know exactly where the piston rod roller (about ⌀8mm, same as the hole on M9k) would be along the curvature of the finger, though it appears the roller comes all way down towards the fulcrum looking at the wear mark.
     
    #35 -   Jun 6, 2019
    Last edited: Jun 6, 2019
  36. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Not a quantitative measure of anything.
    Almost any brake can "lock up a wheel" given the right circumstances.
    For an eye opening counter-example: the right combination of wheel size, terrain gradient, tyre choice + front wheel traction, and rider mass - can easily put every current brake on the market in a state where it can't lock up the front wheel at any realistic human-generated finger input force, using a standard 203mm rotor. That's why some desire brakes with higher peak force than others.

    The 820 lever isn't the same as the 785, and you'd want precise measurements of everything including the piston and cylinder (which are assumed to be the same, but I haven't actually seen data to confirm). A guess of 5% compared to a lever which doesn't even come with the brake is meaningless. There's some starting and ending leverage values for the servo wave levers, specifically the 820 (measured by kind RM members) in the frankenbrake spreadsheet. If they are replicated for other Shimano levers those numbers are assumed and unconfirmed, to my knowledge.

    Not having a go, but sundaydoug and zhendo made plausible statements (which reflect my experience also) comparing two stock brakes, and you've disagreed based on something that isn't even the stock brake.

    If you actually want to compare this stuff, you need to measure the peak leverage (combined mechanical + hydraulic) and peak slave piston force at realistic engagement point - which isn't easy, as it varies even depending on things like the basic reach adjustment setting. Pads only serve as a variable to blur peak force results, the latter should be a static measurement.

    If you're happy with your brakes then great - enjoy them - but to bridge your subjective view over a scientific gap is going to take more than a vaguely measured boat constructed of wild guesses.
     
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  37. Katz

    Katz Monkey

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    Fair enough. I admit what I stated is subjective and as you say, I had non-stock levers (which I really didn't think reduced power all that much, but improved modulation early in the lever stroke). I felt using equal pad materials would make a fairer comparison.

    I do appreciate your thorough technical analysis.
     
    #37 -   Jun 7, 2019
    Last edited: Jun 7, 2019
  38. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Handling my bluntness with absolute grace, equally appreciable.
     
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  39. saruti

    saruti Turbo Monkey

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    if glazed, just put some water and then some sand on the all thing. ride. it will sand it.
    if contaminated, take the pads off, and burn them.