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Discussion Starter · #1 ·
I have a set of Shimano SLX 675 hydraulic brakes on one of my bikes. I haven't ridden this bike for quite a long time but I recall replacing the brake pads over a year ago and it seems like maybe I bled it out. I think I might have got a little mineral oil on the pads and then I ended up spraying them down with brake cleaner and hitting them with a little sandpaper. Anyways I took the bike out yesterday and my God is it loud. It's the loudest squawking sound when you go to stop and definitely the power doesn't feel anywhere near as good as my avid BB7s on my other bike. I'm afraid maybe the pads are ruined. I do know that after I put them on sometime ago I went out and burnished them in real good. Anybody got any tips or should I just throw them away and buy a new set of linings?

I know when I was pulling wrenches professionally on cars and trucks years ago, if we ever accidentally got brake fluid on a brand new set of brake linings we were installing, we simply sprayed them off really good with brake cleaner and installed them and never ever did we have a problem. I don't know why the same thing wouldn't apply for bicycle disc brakes but maybe there's some subtle differences I don't know about? Maybe there's something different about mineral oil versus dot 3 that makes it harder to get out?
 

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Evolutionsverlierer
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Random thoughts out of my still sleepy brain.
What type of pads do you have?
Metal ones are known for screaming like a banshee sometimes.
You might have to hit the pads more with the torch to get the oil out.
Did you clean the rotors too?
Sanding the pads and maybe even the rotors flat might help.
I could not be bothered with all that and went resin.
Good luck.
 

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Discussion Starter · #4 ·
Random thoughts out of my still sleepy brain.
What type of pads do you have?
Metal ones are known for screaming like a banshee sometimes.
You might have to hit the pads more with the torch to get the oil out.
Did you clean the rotors too?
Sanding the pads and maybe even the rotors flat might help.
I could not be bothered with all that and went resin.
Good luck.
I don't remember what pads they are but I know they weren't the super expensive ice technology. I'm pretty sure they're just run of the mill semi metallic pads whatever that is? They are probably resin like you said
 

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Discussion Starter · #5 ·
If they're squealing AND don't have the capability to lock up the wheel, there is probably fluid on the pads.
I can lock up the wheel just fine but it requires considerable more force than my BB7s. But the noise they make is beyond typical squeak. It's enough that if I'm cruising around town I almost don't want to use the brakes because it makes people open their windows and look out lol!
 

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Bike brakes seem way more prone to squeal than car brakes, my guess is it's because of the much thinner rotors, but I'm not sure. I've never had luck cleaning a contaminated brake pad. Heating can work sometimes, but you gotta get them really hot and keep them hot long enough to burn everything off. They are porous, so the oil will really penetrate deep (giggity), so you might think it's clean, but the the next day it will start squealing again. In that case, I always just give up and buy new pads.

Sent from my SM-G960U using Tapatalk
 

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Discussion Starter · #7 ·
Bike brakes seem way more prone to squeal than car brakes, my guess is it's because of the much thinner rotors, but I'm not sure. I've never had luck cleaning a contaminated brake pad. Heating can work sometimes, but you gotta get them really hot and keep them hot long enough to burn everything off. They are porous, so the oil will really penetrate deep (giggity), so you might think it's clean, but the the next day it will start squealing again. In that case, I always just give up and buy new pads.

Sent from my SM-G960U using Tapatalk
Yeah my original post mentioned that I used a propane torch but then I edited it and removed that because I was afraid I was going to get flamed, no pun intended,. I thought I had read that somewhere and that's what prompted me to do it. Anyways I always wondered if you could get a pad too hot doing that and ruin the bond on the back of the lining? There's no way that I can see that brake pads would get as hot under extreme use as they would when you're sitting there hitting them with a torch but maybe I'm wrong?
 

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I've found semi metallic or sintered to be more quiet and reliable than most others. I generally buy discobrakes or truckerco. Kool stop seem great too, and I really like shimano semi-metallic, but discobrakes or truckerco are really cheap, - 4 pairs of semi metallic from disco are $24ish ($11 for one pair if you buy a single pack), I think I paid $35 once at a bike shop for one pair. Rather than spend a bunch more time trying to get the ones you have to work, I'd just buy new ones, and I'm as cheap as just about anybody.
 

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I have a set of Shimano SLX 675 hydraulic brakes on one of my bikes. I haven't ridden this bike for quite a long time but I recall replacing the brake pads over a year ago and it seems like maybe I bled it out. I think I might have got a little mineral oil on the pads and then I ended up spraying them down with brake cleaner and hitting them with a little sandpaper. Anyways I took the bike out yesterday and my God is it loud. It's the loudest squawking sound when you go to stop and definitely the power doesn't feel anywhere near as good as my avid BB7s on my other bike. I'm afraid maybe the pads are ruined. I do know that after I put them on sometime ago I went out and burnished them in real good. Anybody got any tips or should I just throw them away and buy a new set of linings?

I know when I was pulling wrenches professionally on cars and trucks years ago, if we ever accidentally got brake fluid on a brand new set of brake linings we were installing, we simply sprayed them off really good with brake cleaner and installed them and never ever did we have a problem. I don't know why the same thing wouldn't apply for bicycle disc brakes but maybe there's some subtle differences I don't know about? Maybe there's something different about mineral oil versus dot 3 that makes it harder to get out?
Pads are contaminated heavily, change them. Also clean rotors well before putting new ones in. All other procedures (sanding, torching etc..) took way too much time and poor results and in my experience always led to changing pads anyway.
Just change them, they are cheap :)
 
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