Mountain Bike Reviews Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter · #1 ·
I'm reading around on sites, and I always fall back to these lines:

"I have no braking power, what is wrong?

No power could also be caused by the pads being contaminated with oil. Once the pads are contaminated, there is no way to clean them. To fix this, replace the pads, and clean the disc with alcohol."

Why does many major sites about disc brakes write such bull?

On some sites they even suggest buying a new disc. I mean come on, it's steel, definitely non-absorbent!
 

·
Registered
Joined
·
1,008 Posts
Poetic_Dancer said:
I'm reading around on sites, and I always fall back to these lines:

"I have no braking power, what is wrong?

No power could also be caused by the pads being contaminated with oil. Once the pads are contaminated, there is no way to clean them. To fix this, replace the pads, and clean the disc with alcohol."

Why does many major sites about disc brakes write such bull?

On some sites they even suggest buying a new disc. I mean come on, it's steel, definitely non-absorbent!
I think you may be lacking some details. Semi-metallic brake pads (most commonly used) are made from a process called sintering. In short this done by grinding up an organic material and a metallic material, putting the mixture of ground up materials and a binder into a mold, and compressing the desired mixture to the desired thinckness. The pressure causes all the ground up bits to bond into one solid shape. The result is a brake pad with very little metal content, mostly organic content, and a very porous material right through. The pores like to suck up oil and other contamination and are next to impossible to clean out fully.

Solid steel brake pads (which are only used in other specialty cases) would have a coefficient of friction of aprox 0.25, semi-metallic brake pads have a coefficient of friction of 0.35 to 0.45. I would avoid these so called steel brakes pads you speek of, I like stopping power.
 

·
Bad Case of the Mondays
Joined
·
4,009 Posts
Poetic_Dancer said:
I'm reading around on sites, and I always fall back to these lines:

"I have no braking power, what is wrong?

No power could also be caused by the pads being contaminated with oil. Once the pads are contaminated, there is no way to clean them. To fix this, replace the pads, and clean the disc with alcohol."

Why does many major sites about disc brakes write such bull?

On some sites they even suggest buying a new disc. I mean come on, it's steel, definitely non-absorbent!
Ever had a pair of pads get oil on them? I recently did and regardless of how many times I cleaned the pads/rotor with alcohol and sanded them down, the power wouldn't come back to the brakes. New pads were the only answer.

Now I agree the rotor itself isn't going to absorb the oil, but the tiny grooves in the rotor may trap some of the oily substance. I never thought about buying a new rotor just because the old one got oil on it, but the pads are a different story.
 

·
A wheelist
Joined
·
5,991 Posts
Poetic_Dancer said:
No power could also be caused by the pads being contaminated with oil. Once the pads are contaminated, there is no way to clean them. To fix this, replace the pads, and clean the disc with alcohol."

Why does many major sites about disc brakes write such bull?
It's a liability thing. There are NO brake makers that will say that it's ok to decontaminate soaked pads. I'm no lawyer but I'll bet any site that says it's ok to decontaminate could be sued if there is an incident related to taking their suggestion.
 

·
Registered
Joined
·
799 Posts
Mike T. said:
It's a liability thing. There are NO brake makers that will say that it's ok to decontaminate soaked pads. I'm no lawyer but I'll bet any site that says it's ok to decontaminate could be sued if there is an incident related to taking their suggestion.
The very reason Marzocchi has shoddy manuals these days ...(that didn't sound too bitter did it)
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #6 ·
Jdub said:
Ever had a pair of pads get oil on them? I recently did and regardless of how many times I cleaned the pads/rotor with alcohol and sanded them down, the power wouldn't come back to the brakes. New pads were the only answer.

Now I agree the rotor itself isn't going to absorb the oil, but the tiny grooves in the rotor may trap some of the oily substance. I never thought about buying a new rotor just because the old one got oil on it, but the pads are a different story.
Yup, cleaned with a substance called "Bräkleen" or disc brake cleaner for cars.
Remove pads, (don't dare spray the calipers unless it's Really bad) rub pads with liquid and my thumb, then polish the disc with a paper towel and liquid.

Afterwards I get up a steep tarmac/asfalt hill, and pedal to the metal with brakes depressed slightly until the brake pads starts to smell burnt.. Then they're fine again. =p

Small amounts of the cleaning substance stays, but it will burn up a lot easier than the oil that was on to begin with.. Well, it's cheaper, and adding teflon every day to the darn fork has it's side effects.

But yeah, that about liability etc made sense.. I forgot for a moment that USA is the country where you can sue McDonalds for a million $$ because you burnt yourself on your own coffee..
 

·
(aka SS_MB-7)
Joined
·
924 Posts
Mike T. said:
It's a liability thing. There are NO brake makers that will say that it's ok to decontaminate soaked pads. I'm no lawyer but I'll bet any site that says it's ok to decontaminate could be sued if there is an incident related to taking their suggestion.
As Senior MT indicated, it's a liability thing. In this era of "sue anybody and everybody (even if it is my own fault)", it's best and easiest for brake manufacturers to just recommend new pads should they become contaminated with oil. However, that doesn't mean you can't try.

Over the years, I've accidentally contaminated a few sets of pads and have always "baked" the contaminate-out without any issues. I just place the pads on a cookie sheet, pad-side-up, set the oven for 400F, open the windows, turn on the fan and let it go for about 20 min. Once cooled, just lightly sand-off the top layer of pad, wipe the rotor with isopropyl alcohol and then, take a quick test ride around the block to make sure everything stops, as expected, before hitting the trails.

I've done this with Hope, Formula, Shimano and Magura pads and I've never had any issues.
 

·
A wheelist
Joined
·
5,991 Posts
1speed_Mike said:
As Senior MT indicated, it's a liability thing. I've done this with Hope, Formula, Shimano and Magura pads and I've never had any issues.
And I've done it myself too by using a propane torch outside and heating the metal backs until gasses rise, burn and subside. A scuff of the pads and we were back in business.

Can anyone really imagine ANY brake company telling us it's ok to do that? Errrr no.

Mike T. (mcm # 717 & FOG)
 

·
Who are the brain police?
Joined
·
10,112 Posts
Cleaning out the oil: I've had great luck using a culinary blow torch to bake out contaminants. Hold the pad by the base w/ a pair of pliers then torch the sucker until its glowing red. When it stops smoking, the contaminants are gone or reduced to carbon. Then soak in isopropyl alcohol to help remove the reduced residue then lightly sand to deglaze the surface -if the pad material has been "smoothed out" from use..

Its a process, but its cheaper than buying a new pad -especially if there isn't much wear on them.
 

·
Registered
Joined
·
734 Posts
"Metal pads" are not steel they are sintered bronze. They are fairly common and are more powerful (stopping wise) than standard (organic/resin) or semimetalic pads. (there are some super soft organics made for downhill that meet or even exceed the stopping power of metalic pads but wear so fast ththat they are only really useful for DH racing)

That said full metalic pads (being sintered) are porous and will absorb oil or other contaminants (brake fluid, chain lube) Cleaning contaminants off disc brakes is difficult (as anyone who has contaminated thier pads can tell you) as the surfaces are very striated (covered with tiny grooves)

I have found that the best bet for contaminated discs (if you have metal pads) is clean them (and the rotors) in the dishwasher (the hot water and strong detergent will remove the contaminant from the surface) and if you have organic/resin or semimetalic pads throw them out and put the rotors in the dishwasher.
 

·
MTB Rider
Joined
·
3,007 Posts
It's not just legal ...

1speed_Mike said:
As Senior MT indicated, it's a liability thing. In this era of "sue anybody and everybody (even if it is my own fault)", it's best and easiest for brake manufacturers to just recommend new pads should they become contaminated with oil. However, that doesn't mean you can't try.

Over the years, I've accidentally contaminated a few sets of pads and have always "baked" the contaminate-out without any issues. I just place the pads on a cookie sheet, pad-side-up, set the oven for 400F, open the windows, turn on the fan and let it go for about 20 min. Once cooled, just lightly sand-off the top layer of pad, wipe the rotor with isopropyl alcohol and then, take a quick test ride around the block to make sure everything stops, as expected, before hitting the trails.

I've done this with Hope, Formula, Shimano and Magura pads and I've never had any issues.
It's also a nice way of getting people to replace pads that can be cleaned.

Isopropyl alcohol doesn't do squat for cleaning out contimants. DENATURED alchohol ... well, thats a different matter. My method is soaking the pad in denatured alcohol. And of course there is the blow torch method two.

I plan on keeping my discs clean by keeping them OUT of the LBS where they like to spray down your chain with teflon lube without regard to what is behind it.

At $10-$20 an axel, repairing pads is definitely worth it. The WORST thing that can happen is that you'll destroy a pad that you couldn't use anyway.
 

·
Registered
Joined
·
3,356 Posts
Oven Works!

1speed_Mike said:
Over the years, I've accidentally contaminated a few sets of pads and have always "baked" the contaminate-out without any issues. I just place the pads on a cookie sheet, pad-side-up, set the oven for 400F, open the windows, turn on the fan and let it go for about 20 min. Once cooled, just lightly sand-off the top layer of pad, wipe the rotor with isopropyl alcohol and then, take a quick test ride around the block to make sure everything stops, as expected, before hitting the trails.
Wow thank you, I contaminated quite badky a set of pads (don't ask how, I am paying the admission price to brake heaven to the fullest). Squeeled like a ... disk-brake ... horribly! but I followed instructions and baked the pads (at 450 for 25', just to add variety), sanded-off, clean throughly with denaturated alchool and ... bingo: everything is fixed :) :)

Mid way through, I could see one of the pads fuming, further proof ( :confused: ) of good baking in action ( :rolleyes: )
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top