Has anyone had this before? Any idea what is causing the contamination?
Bike hasn't been used in a few months, brake was really noisy, and I get these metallic blobs oozing out of the pads when I get a blowtorch on them and heat them up.
It's happened to several pairs of pads this year (Various brands, so its nothing to do with any specific brand), but I'm not sure whats causing the contamination
Image blocked at work, so I can't see them.
Bit what specifically are the pads? Sintered? If so, they contain metal in the pad material so maybe you are just melting out the metal from the pad itself.
Sintered pads are generally squeally in wet weather, which correlates with your comment about the brakes being noisy.
It looks like blobs of solder all over the pads. And yes, they are sintered pads, I did wonder if I potentially over-heated them with the MAP gas blowtorch, but I didn't think I got them that hot. Regardless, their braking performance had gone so they were definitely contaminated.
RE the noise... nope, this was full 'my brakes are ****ed' howling like a banshee noise with a massive lack of power, also just riding them out the garage on a dry day, and the front was fine.
Reposting images from another host incase nobody can see them...
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Very curious.
Now science demands that you give a brand new sintered pad the same blowtorch treatment, to see if it is just the metal bits melting.
Now science demands that you give a brand new sintered pad the same blowtorch treatment, to see if it is just the metal bits melting.
I'm more interested in seeing if they'll get hot enough that the braking material subsequently separates from the backing under load.
Not been used for a while and now howling/ineffective? These are Shimano calipers, right?
It'll be the fluid leaking past the seals and reacting with the pad material. 🙁
@chakaping, debated doing this, obvs didn't want to throw away a set of good pads!
@scotroutes This is absolutely what happens. Ask how I know. It's easy to get them glowing red under a MAP gas blowtorch. They may then fall off after a bit of heavy braking. Worth noting that in the pics above, I hadn't heated them up anywhere near that much
@submarined, yes, they are shimano. Using LHM clutch fluid if that makes any difference. I hadn't noticed any leakage, but thats not to say there isn't any
Sintered pads are very noisy until they heat up...tend to be worse on a cold day and first lot of braking being done...however, the leaky caliper suggestion isn't entirely off the mark either.
Lets move away from the sintered/non-sintered train of thought, because the pads are contaminated. Just curious if anyone else has had this and what the likely cause of contamination is for metal to be oozing out of the pads.
@dickbarton fyi I've used sintered pads for the last 15 years and never had any issue with noise unless it's especially wet, never heard of sintered pads being noisy unless they have heat in them either.
Fair enough...contamination could very well be leaky calipers, although how that makes the metal turn to blobs when blowtorched I've no idea.
I've had a similar looking thing with pads that I've heated on the gas hob.
As far as I'm aware I just got them too hot and it melted the metal particles in the friction material.
For what it's worth I used the pads until they were worn out and they stayed in one piece.
You make your own choices though.
I did wonder if I potentially over-heated them with the MAP gas blowtorch, but I didn't think I got them that hot.
A quick Google suggests that in ambient air, a blowtorch can reach temps of 2000deg. C.
The particles in sintered pads are very small, so will absorb that heat & melt pretty fast.
It sounds like you might have an issue with contaminated pads, but I think the balls of metal are a red herring & you are just overheating the pads with a blowtorch to get this effect.
Maybe you just have the leaky calipers issue which can affect Shimano brakes?
You mention using clutch fluid - presumably for the hydraulic fluid in the brakes?
Is this compatible with the seals in Shimano brakes? I am not familiar with it.
I did wonder if I potentially over-heated them with the MAP gas blowtorch, but I didn't think I got them that hot.
A quick Google suggests that in ambient air, a blowtorch can reach temps of 2000deg. C.
The particles in sintered pads are very small, so will absorb that heat & melt pretty fast.It sounds like you might have an issue with contaminated pads, but I think the balls of metal are a red herring & you are just overheating the pads with a blowtorch to get this effect.
Maybe you just have the leaky calipers issue which can affect Shimano brakes?
You mention using clutch fluid - presumably for the hydraulic fluid in the brakes?
Is this compatible with the seals in Shimano brakes? I am not familiar with it.
Yeah I think you're right, and I'll be more careful with the blowtorch in future 🤣 Although I'm sure I've heated other pads more than I did for these ones in the past with no blobs, but maybe not. The pads are straight in the bin regardless, not worth the risk.
Yeah LHM is a compatible mineral oil that you can use with Shimano, cheaper and easier to get than the normal stuff, I've used it for 10+ years and never had an issue with the seals (other than this possible leak)