mineral oil on pads permanent?

Lifespeed · Oct 2, 2010

OK, this may be a dumb question, but here goes:

I cut a hose on my Shimano XT M765 180mm front brake during a 'minor incident'. So I bought the new parts, installed, and bled the brakes. Despite my best effort to keep a rag around the caliper, I think some mineral oil got on the pads.

I cleaned the caliper/pads with brakeclean and compressed air, but now the brake squeals like a beaten dog. Doesn't really stop that great either. The pads are Shimano semi-metallic.

Did I blow it? Do I need to buy new pads, or will any residue burn away with use?

Lifespeed

slfjas · Oct 2, 2010

Try either heating the pads in a frying pan you don't use for anything else, or using (very gingerly) a torch to heat the braking surface, until they stop smoking

DGB · Oct 2, 2010

Since you got some fluid on the pads, you are very likely to have also gotten it on the rotors. Clean the rotors with some alcohol to remove any residue and torch the pads again to ensure that all parts are now contaminant free.

Lifespeed · Oct 2, 2010

Thanks, I'll try that. DOT fluid is pretty harmless (to brake pads, anyway), but mineral oil . . . well, it's oil.

frdfandc · Oct 3, 2010

DOT brake fluid acts just like mineral oil when on brake pads.

Gotta clean it all off, and if you can't get it completely off the pads, time for new pads.

ncativo · Oct 3, 2010

But how can you tell whether the brake pads have brake fluid on?

gmcttr · Oct 3, 2010

ncativo said:
But how can you tell whether the brake pads have brake fluid on?

They don't work well.

Cutbert · Oct 3, 2010

disclaimer: be careful, you are on your own!!

1) get 91% rubbing alcohol at the pharmacy (not 70% - not strong enough), totally submerge your pads for a couple of hours, see the mineral oil or DOT fluid float to the top.
2) use a paper towel to skim the fluid off the top before trying to remove the pads from the soak.
3) If they are organic or resin pads don't torch! Allow to dry wrapped in paper towels.

If Sintered Metal, then you may use the torch method but not required. (I use a heat gun not flame) Don't get too close with the flame or too hot!! Do it outside though, highly flammable!! the alcohol will flash off immediately, so anything else burning is likely any remaining oil.
4) allow to cool naturally.

Use 91% rubbing alcohol to clean your rotors, pistons, calipers, etc....

Always keep a can of spray brake cleaner around, it's great to have on hand for quick brake cleans after a ride. I get the cheap stuff at Wally World (Walmart) in the auto section.

chauzie · Oct 4, 2010

I wonder if soaking the pads in a light acid will remove the oil? You can try lemon as an acid. Or if you prefer strong acid, to go Home Depot or any hardware store and get sulfuric!

I remember one time i got mineral oil on my semi-metallic pads, and I just soaked it in lemon juice for a few days and that got most of the squeal away, and brought back the braking power. And after one ride, the pads were back to 100% normal as they wore down.

jeffscott · Oct 4, 2010

frdfandc said:
DOT brake fluid acts just like mineral oil when on brake pads.

Gotta clean it all off, and if you can't get it completely off the pads, time for new pads.

It burns off in the fry pan as well.

jeffscott · Oct 4, 2010

Cutbert said:
1) get 91% rubbing alcohol at the pharmacy (not 70% - not strong enough), totally submerge your pads for a couple of hours, see the mineral oil or DOT fluid float to the top.
2) use a paper towel to skim the fluid off the top before trying to remove the pads from the soak.
3) If they are organic or resin pads don't torch! Allow to dry wrapped in paper towels.

If Sintered Metal, then you may use the torch method but not required. (I use a heat gun not flame) Don't get too close with the flame or too hot!! Do it outside though, highly flammable!! the alcohol will flash off immediately, so anything else burning is likely any remaining oil.
4) allow to cool naturally.

Use 91% rubbing alcohol to clean your rotors, pistons, calipers, etc....

Always keep a can of spray brake cleaner around, it's great to have on hand for quick brake cleans after a ride. I get the cheap stuff at Wally World (Walmart) in the auto section.

Resin pads are fine in a fry pan with the range set at medium heat takes about 5 to 7 minutes for it to stop smoking.

Cutbert · Oct 4, 2010

Acid?

That's an interesting thought. I'd be concerned about it eating at the brake compound though. If I'm dealing with oils, I want something to only attack the oils. Glycol or silicone, the same, which is why I prefer the rubbing alcohol.

Plus, I need the lemons and limes for my vodka!

yetibetty · Oct 5, 2010

chauzie said:
I wonder if soaking the pads in a light acid will remove the oil? You can try lemon as an acid. Or if you prefer strong acid, to go Home Depot or any hardware store and get sulfuric!

I remember one time i got mineral oil on my semi-metallic pads, and I just soaked it in lemon juice for a few days and that got most of the squeal away, and brought back the braking power. And after one ride, the pads were back to 100% normal as they wore down.

I have done the same, just sat the pads in a saucer of lemon juice over night and all was back to normal. Smells nice and is safe to use too.

Fred Smedley · Oct 7, 2010

The stuff you want is brakeclean, a aerosol solvent made to clean oil /fluid from brake parts, any auto store will carry for 3 or 4 $

sm4 · Oct 8, 2010

if disc brake pad surface contain brake oil, rupt with cloth to dry it, put it back caliper, ride out soft touch the brake lever , the brake pad will rupt the rotor create heat up to 200 degree celcius enough to smoke ( vaporise the oil).

mineral oil on pads permanent?

Lifespeed

slfjas

DGB

Lifespeed

frdfandc

ncativo

gmcttr

Cutbert

chauzie

jeffscott

jeffscott

Cutbert

yetibetty

Fred Smedley

sm4

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