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In trying to change the brake pads on my mountain bike, I managed to get oil on my new pads and empty out all the brake fluid, and consequently also get some oil on the disc. I took the bike to the shop and they are now telling me I need to change the pads and the disc. I can understand the pads, but do I really need to change the disc or is the guy (girl actually) just scamming me. The disc is not soaking in oil, from what I can tell it just has a bit of oil here and there.

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A while ago I managed to get grease on my front disk,by the time I realsed it was grease it was to late. I tried various methods of cleaning it ,but failed. My last resort was some 1000 grade wet and dry and soapy water, the disk now looked like new. Fited new pads now o.k –  Fred Jul 18 at 14:15
    
I got oil on my pads once. After about 2-3 months it eventually wore off and break performance was restored. But if you can't wait that long, go for cherouvim's answer. –  Leo Ufimtsev Jul 18 at 15:16

3 Answers 3

up vote 17 down vote accepted

First of all you need to tell the LBS (local bike shop) that the disk can be "fixed". Then you need to find another LBS because they are either amateurs or are simply trying to make you buy stuff that you don't need.

You need to remove the oily disk from the bike and use a bike degreaser or alcohol on it to remove all oil. Rub with a clean dry cloth or kitchen paper and repeat. While finishing the process avoid touching the disk with bare hands on the face where the pads contact it because fingers leave grease as well.

Regarding your pads, these can be "fixed" as well in case they are sintered. You'll clean them using a degreaser or alcohol and slightly grind them (let's say remove ~0.2 mm of surface) with a thin sand paper. This will make sure that the pads are like new. Then you'll do whatever you do when using new pads (bed them in).

If the pads are not sintered but are organic then the above process may not do the work because organic pads can suck some oil inside (like sponges but not that much). I've heard of people boiling the pads in a frying pan with tap water and a bit of dishwasher soap but I don't know whether this will work. If you do that make sure you don't inhale any of the steam and also use an old pan which you'll never ever going to use again for cooking.

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Thanks a lot for this information. The pads are sintered so I can fix these as well. Wow! this person really is trying to scam me. I will get the bike back and do the whole thing myself. Is it tricky to put fluid back in the brakes? –  Poorav Jul 30 '13 at 9:11
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I've tried to fix too many contaminated pads to learn it is not worth the effort. They will not be as good as before contamination. @Poorav, you can give it a go, but don't expect magic. As for bleeding breaks - it is quite tricky, and requires special tools. –  trailmax Jul 30 '13 at 9:16
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+1 cherouvim. I am sick and tired of bike shops that tell me I need to change a whole bunch of stuff. One friend recently was told he needs to change his several-months-old mid-range cranks because he is changing his chain! –  Vorac Jul 30 '13 at 9:17
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Yes, bleeding your brakes is a bit tricky. It also requires a bit of new oil, syringes and torx keys. I suggest you go to a good LBS for that. –  cherouvim Jul 30 '13 at 9:48
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Can also burn the oil off the pads. Put them on some concreate, poor half a teaspoon of mths on them, stand back and set them a light. However, I am with @trailmax, its a lot of effort for what will always be a dodgy set of pads –  mattnz Jul 31 '13 at 0:51

Just to add to the top answer - brake cleaner (sold by bike shops and car service places) is the ideal product for cleaning your brakes - just spray it on liberally and let it drip off.

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Will this also work for the brake pads? –  Poorav Aug 2 '13 at 9:53
    
Not sure if it'll do any good, but it'll certainly do no harm. When you're working on car brakes (same concept) you spray it all over them –  pa1983 Aug 20 '13 at 14:44

Degreaser or brake cleaner should be just fine on the disks. I've had success with just rinsing pads in boiling water - the heat drives off the oil.

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