Oil on discs - help please

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Oil on discs - help please
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flag BR3N
Posted: Feb 15, 2012 at 6:24 Quote
so without thinking i oiled my discs a couple of weeks ago to get rid of the squeak, it has now been pointed out to me that that was incredibly stupid. How would i go about cleaning them, and getting them back to their original performance?

thanks.
flag techyiam
Posted: Feb 15, 2012 at 6:38 Quote
Water-based de-greaser.

Simple Green is effect and is biodegradable.

It may take a few applications.

For something contaminated this extensively, it may be better to take out the pads and wash them separately from the rotor.

After cleaning and reassembly, your braking power initially will usually be less than before, but with usage, it will get better and better. Eventually, your brake can perform better than before.

After the first cleaning, subsequent cleaning may consist of merely spraying Simple Green on the rotor, with the wheel and pads installed on the bike, rotate the wheel, and wipe off with clean paper towel or tissue paper.
flag dobby
Posted: Feb 15, 2012 at 6:47 Quote
If there is a lot of oil, your best bet is to just replace the pads.
People will recommend heating the pads, boiling them, filing the top layer off etc. But if the oil has soaked right in, nothing beats a new pair of pads.

With the rotor, clean it with Isopropyl alcohol and wipe it down with workshop cloth. Repeat a few times if need be.

Then just re-bed in the pads as you normally would.
flag techyiam
Posted: Feb 15, 2012 at 8:10 Quote
As the saying goes, there is no substitute for experience.

Don't just talk the talk. You got to walk the walk.

Braking demands on bicycles is nowhere that of race replica sport motorcycles going 200+ and decelerating at very high rates. Even with engine oil or automotive grease on the pads and rotors, the water-based de-greaser, alone, can restore performance for sport bikes, with ease for cars, and trivially for bicycles.
flag pbuser102331
Posted: Feb 15, 2012 at 8:21 Quote
techyiam wrote:
As the saying goes, there is no substitute for experience.

Don't just talk the talk. You got to walk the walk.

Braking demands on bicycles is nowhere that of race replica sport motorcycles going 200+ and decelerating at very high rates. Even with engine oil or automotive grease on the pads and rotors, the water-based de-greaser, alone, can restore performance for sport bikes, with ease for cars, and trivially for bicycles.

At the same token a disc brake on a trivial bicycle will never ever reach the temperature of the race replica car or motorcycle as the mass/speed and thus deceleration is a lot smaller,these temps that the race replica stuff will hit will be enough to burn of/vaporize the grease/oil.

It's alright walking the walk but don't talk the talk if your clueless.
flag techyiam
Posted: Feb 15, 2012 at 8:40 Quote
My recommendation is derived from experience with cars, motorcycles, and bicycles with lubricant on them. No, high temperatures is not a requisite.

I have shared a data point. Have you? Or are you are sharing your personal opinions, and assumptions.
flag pbuser102331
Posted: Feb 15, 2012 at 8:46 Quote
techyiam wrote:
My recommendation is derived from experience with cars, motorcycles, and bicycles with lubricant on them. No, high temperatures are not a requisite.

I have shared a data point. Have you? Or are you are sharing your personal opinions, and assumptions.

200+ ain't a data point.

And you can't compare the trivial bicycle with motorcycles and cars as the temps are not the same.
flag techyiam
Posted: Feb 15, 2012 at 9:06 Quote
I did not state that going 200+ (implying high temperatures by you) was one of the requirements to restore oil contaminated disc brakes.

Let me ask you this. Would you ride at 200+ (on a closed circuit of course) on brakes that are not properly functioning?

Of course not, no one would.

Hence, the point was that the method applies even to very high performance applications. The 200+ bit is only relevant after braking performance has been restored fully.

In any case, my experience includes bicycles.

In fact, it was much easier to restore fully braking performance for bicycles. And hence, trivially.

Elevated temperatures as a requisite in my prescribed method was only raised by your assumption. It was never a fact that was observed. In fact, one needs to ride slowly and cautiously until braking performance is restored, as implied by my original post. And this goes for car and motorcycle applications as well.
flag pbuser102331
Posted: Feb 15, 2012 at 9:49 Quote
But would it not depend on the amount of contamination,yes degreaser would work to an extent but it would depend on the contamination level/or how long the oil/grease was left to soak into the pad material.

On a car/motorcycle brake the temps involved would help burn of the oil/grease.
flag superbikes
Posted: Feb 15, 2012 at 10:07 Quote
Sandpaper will clean your disk but get new pads .
flag techyiam
Posted: Feb 15, 2012 at 10:13 Quote
marquis wrote:
But would it not depend on the amount of contamination,yes degreaser would work to an extent but it would depend on the contamination level/or how long the oil/grease was left to soak into the pad material.

On a car/motorcycle brake the temps involved would help burn of the oil/grease.

No, not in my experience.

Put engine oil or automotive grease on your car or motorcycle rotors (closed circuit and buy lots of insurance) and see if high temperatures will burn it all off?

It doesn't, at least not in the sense that it would allow it to fully restore before-contamination performance. Once a rotor is contaminated with a greasy, or an oily substance, braking would degrade, and before-contamination braking performance would never return by itself, even with multiple passes of high speed braking.

I can only shared what I have observed.

Here is a thought. Engine oil needs to provide protection for both cylinder walls and piston rings inside an internal combustion engine.
flag vwcabrio82
O+
Posted: Feb 15, 2012 at 17:24 Quote
the brake material is absorbent and will soak oil into them most times to the point of not getting it out. if this was a case of using spray oil on your chain and perhaps got some on a disk then realized it immediately you may be able to clean them using a break cleaner, however soaking the pads also runs the risk of weakening the glue that is used to adhere the pad to the plate.

all arguing aside, some solid advise as given above, clean disks with either auto brake cleaner (outside) or alcohol, and best bet to purchase new pads.
flag hampsteadbandit
Posted: Feb 16, 2012 at 8:34 Quote
techyiam wrote:
As the saying goes, there is no substitute for experience.

Don't just talk the talk. You got to walk the walk.

Braking demands on bicycles is nowhere that of race replica sport motorcycles going 200+ and decelerating at very high rates. Even with engine oil or automotive grease on the pads and rotors, the water-based de-greaser, alone, can restore performance for sport bikes, with ease for cars, and trivially for bicycles.

sorry, but this information is completely incorrect, if only it was that simple....(de greaser)

I installed the first hydraulic Sachs disc brake onto a mountain bike back in 1993 before Rockshox's forks even had disc brake mounts,
photo
we did lots of development works with Sachs (now SRAM) on the early disc brakes

and have worked on literally 1000s of pairs of hydraulic and mechnical disc brakes since then, including many contaminated with suspension fluid, chain lube and other substances

the only solution to this problem is to replace the pads with new disc brake pads, clean the rotor and caliper bay with iso alcohol and key the rotor track with fine grit paper (this removes old brake pad material from the rotor and helps the new pads bed in properly)

you will not achieve full stopping power or correct brake modulation on a bicycle brake that has been contaminated by removing the contaminant with degreaser Wink



something to be very aware of when making any comparisons (brakes, suspension, etc.) between motorised vehicles like automobiles / motorcycles, and bicycles is that bicycles are considerably lighter

the ratio between the weight of the rider and the vehicle is very different compared to cars and motorcycles, which completely changes the dynamics of suspension and braking

many early suspension designers in mountain biking made the mistake of taking motorcycle technology and trying to apply it to mountain bikes with very poor results.
flag superbikes
Posted: Feb 16, 2012 at 8:45 Quote
I agree with this as its how I have fixed this problem before. Allso when I have new pads and clean rotors I find a splash of water on the helps to get them to bit faster but that's just how I do it really
flag techyiam
Posted: Feb 16, 2012 at 10:51 Quote
hampsteadbandit wrote:
...sorry, but this information is completely incorrect, if only it was that simple....(de greaser)

... including many contaminated with suspension fluid, chain lube and other substances

...the only solution to this problem is to replace the pads with new disc brake pads, clean the rotor and caliper bay with iso alcohol and key the rotor track with fine grit paper (this removes old brake pad material from the rotor and helps the new pads bed in properly)

...you will not achieve full stopping power or correct brake modulation on a bicycle brake that has been contaminated by removing the contaminant with degreaser Wink

You may not have been successful, but I certainly have been. It is not my opinion or assumption. My successes were observed fact. I provided my data point. You provided yours. Neither of us have proved anything. Although you have taken your assumptions and unsuccessful decontamination attempts as proof.

bigquotessomething to be very aware of when making any comparisons (brakes, suspension, etc.) between motorised vehicles like automobiles / motorcycles, and bicycles is that bicycles are considerably lighter

Wow, what a revelation. A bicycle has less mass than a car or motorcycle. It would help your case if you can provide facts that is relevant to the topic at hand.

bigquotesthe ratio between the weight of the rider and the vehicle is very different compared to cars and motorcycles, which completely changes the dynamics of suspension and braking

You failed to realize that in cornering, for a small displacement motorcycle, the engine weight and the moment that it produces about the "rolling axis" is what at issue. On larger motorcycles, the greater inertia would make counter-steering a very important part. I have successfully applied what I learnt about cornering on bicycles to motorcycling, and vice versa. Once one understands the underling physics of the cornering dynamics of a two wheel tandem vehicle, it is not a hard thing to do. Can you enlighten us with your deep understanding of the vehicular dynamics among the vehicles that you have raised? And how it relates to the current discussion topic. You have left out all the details so far.

bigquotesmany early suspension designers in mountain biking made the mistake of taking motorcycle technology and trying to apply it to mountain bikes with very poor results.

You are side tracking. Totally irrelevant to the topic at hand. Regardless, I'll nibble a little. High mount single pivot, and direct shock actuation (some via a link:progressive and linear) certainly still seem to be used in current rear suspension designs. Look at what La Pierre did with their DH bike designs: from virtual pivot to a high mount single pivot with a link for shock actuation. Other examples include 2012 Transition TR450, 2012 Orange 224 Evo, 2009 Trek Session 10, 2010 Commencal Supreme DH v2, Cam Zink's Corsair/Hyper bicycle. Trek currently has a great design, albeit with higher stresses in the main swingarm. But take a closer look at the design. It is effectively, a high mount single pivot with very direct shock actuation. One needs to focus more on the main swing arm (seat stay link) and how the impact energy is very directly and thus effectively transmitted to the bottom eyelet of the rear shock. The upper links give benefits which include anti-brake jack, and floating shock advantages. Those engineers/designers at Trek are quite clever, IMHO.
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