Brakes Pads keep getting contaminated

My brake pads were contaminated. Making howling noises and have to squeeze extra hard – two figure braking – and still not even getting the same stopping power as one figure braking on good pads – so all the signs of contamination.

I threw them away and put new ones on. Within very little distance the new pads were contaminated again.

I thought Muc-Off might have been doing it, so stopped using it. Put new pads on again. After a very small amount of riding, (again, less than 200 miles) once again, the brakes were contaminated.

I’ve stopped using any spray-based lubricants since the first incident, so can’t be that.

Anyone know what could be the cause of this problem ? Also how to de-contaminate the pads because I’ve now got four contaminated pads that I don’t want to throw away.

What brakes? Shimanos?

Yes its a Specialised Camber Evo 2015 with Shimanos brakes

Did you clean your discs when changing pads. And are the pads deffo contaminated and not needing calipers centred/ adjusted.

i had that with a set. could never get any consistent power. if I got them to work, next ride out it would be gone. bled them multiple times, changed pads several times. degreased the rotor numerous times.

eventually tried a different rotor and it was like night and day.

so try a new rotor.

Rotors rotating the right way? I discovered years ago what a difference to brake noise that can make… 😳

My dad has some 2014 Shimanos on a second hand bike he bought, they seem to be contaminating pads as well, I’ve assumed a small leak but he’s isn’t really clued up enough to check so we haven’t confirmed yet.

Have there been any other leaky Shimano issues since those seals that kept failing in the cold a few years ago?

Brakes spongy? If so I’d suggest a caliper leak.

I’m coming round to the theroy put forward in this thread that Shimano brakes can suffer imperceptible calliper seal failure which puts oil on your rotors. I’ve got two sets of Shimano XT’s that are two years old and I am struggling to get them to bite.

http://singletrackworld.com/forum/topic/am-i-glazing-my-brake-pads

Other than that I’ve had contamination from transporting the bike on my car before.

Within very little distance the new pads were contaminated again.

Assuming you don’t have a leak….Could be the disks weren’t cleaned properly between changing pads ie washing up liquid hot water and wet and dry?

Shouldn’t be necessary normally but with contaminated pads.

Best way to decontaminate pads is by heating them, I place them on an electric hob, once they stop smoking they’re done, finish with (dry) wet n dry and re-bed them.

I’ve had this problem with all of my shimano pads. My solution is this, and normally only have to do it once or twice for the life of the pad:

1) Remove pads and spray with liberal amounts of brake cleaner and wipe clean with lint free fresh cloth
2) Place pads in oven on max heat for about 20 minutes
3) Remove pads and using a pair of tongs hold them over a burning flame for 30 seconds each
4) Allow to cool and then sand gently to remove any glaze
5) Clean rotors with brake cleaner and clean lint free cloth
6) Reinstall pads and do several fast, hard brakes to a complete stop (don’t drag them)

This works for me on Shimano sintered pads.

Second for the rotor. I currently have the same issue. Taken pads off twice – sanded them, cleaned them, heated them and also done the same to the rotor. After 5 mins of hard riding they are howling again and stopping power is rubbish. This has only recently started. I checked the rotor and I can feel noticeable wear on it. I reckon it must be the rotor. I have a spare one, so going to give it a try.

Between pad changes I’ve always cleaned the discs with disc brake cleaner rubbed over them with a cloth.

The discs are new although strangely the problems seemed to start around then from memory.

Both front and rear pads seem to get the problem – howling and poor stopping power.

Both brakes, or just front or rear? If it’s both it’s more likely to be an environmental issue.

When I’ve contaminated pads in the past I like to follow a scorched earth policy – discs cleaned to within an inch of their life with disc brake cleaner, and the callipers and clean everything before I even unbox the new pads.

Shimano brakes are known to suffer from small leaks that can leave you with oil on the discs – using non-shimano mineral oil (they’ll tell you) can cause this as it doesn’t play nicely with their seals.

As for decontaminating pads, it’s not easy done, but in the past when I’ve been away and cannot get any new ones, I’ve cleaned them with brake cleaner, then sanded off the top layer of friction material until it’s back the the ‘new pads’ colour. it’s not great, they take ages to bed in and it’s not always a perfect job, but it works.

If your discs are new give them a rub with (dry) wet and dry paper to roughen them up a bit. I had new discs on mine and the brakes were crap for a while.

I’ve had this problem with all of my shimano pads. My solution is this, and normally only have to do it once or twice for the life of the pad:

1) Remove pads and spray with liberal amounts of brake cleaner and wipe clean with lint free fresh cloth
2) Place pads in oven on max heat for about 20 minutes
3) Remove pads and using a pair of tongs hold them over a burning flame for 30 seconds each
4) Allow to cool and then sand gently to remove any glaze
5) Clean rotors with brake cleaner and clean lint free cloth
6) Reinstall pads and do several fast, hard brakes to a complete stop (don’t drag them)

This works for me on Shimano sintered pads.

Where on earth did you learn to do that? Ive had a guess at how to solve things in the past but really…. 😕 😯 😛

Where on earth did you learn to do that? Ive had a guess at how to solve things in the past but really….

Trial and error mainly! Lots of advice on various forums all clobbered together 😀

Where on earth did you learn to do that? Ive had a guess at how to solve things in the past but really….

Strangely, I have on/off problems with one set of XTR brakes too, and my ultimate fix routine is pretty much exactly the same as that. Seems to work, but is a bit of a ball ache to do. Took a bit of thought to figure it all out.

If you want to clean the pads and rotors, you need to burn the contaminants off.
Ive done my friends and my own, and I just use a basic blow torch you can get from most DIY shops.
Just keep the flame on them until they stop smoking, and thats it. Works every time I have done it.

I think this may be a known QC issue with some XT Shimano brakes.

I had it – pads would become contaminated and have to be discarded after just a few rides.

I replaced the brakes with some others (BB7 found in the garage) and it’s been fine ever since.

I returned them to CRC (still under warranty) and they were replaced FoC very quickly.

…disc brake cleaner…

After using a few I now only use alcohol, which also doubles for cleaning the inside of forks.

Always amusing when the chemist asks you why you’re buying it.

I use meth(ylated ethanol) – as pure ethanol is rather hard to come by, unless you know a chemist.. 😉

Disc brake cleaner is snake oil, when you can buy 500ml meths for £1.75

I’ve had an ongoing squealing issue with my rear SLX and a caliper leak was suggested, however there’s absolutely no loss of power are sponginess (it’s been going on for months with no loss of lever feel), so I’m at a bit of a loss.

I think this may be a known QC issue with some XT Shimano brakes.

Certainly enough threads around to support this theory, as my own experience of XT is that they do eventually weep from the pistons.

Fing shite IMHO as when they work they are an awesome brake, in the end I got so fed up I’ve ditched them for Hope.

Always amusing when the chemist asks you why you’re buying it.

Mine eyed me suspiciously and flat out refused to sell it to me lol.
Just as well you can get 5L tubs of 99.9% IPA on ebay.

Had the same issue with the wife’s rear Deore. Turned out there was a very small leak at the piston which you could just see when squeezing the brake with the bleed block in. New calliper sorted it.

IPA for cleaning.

Anyway, sounds like a caliper leak to me if it keeps happening after cleaning and new pads etc. Just one of the brakes? If the front there’s a slim chance of a leak from brake lever or even a Reverb lever, could drip onto the front disc.

I’ve had something like this before. 4 sets of XT and only one set having the issue. They were fine when the pads were new and just fitted or had just been treated to a dose of the blowtorch. Finally narrowed it down to (and this sounds like bs) the location of the stand in the room I store my bike in. Yeah, no idea. The longer the bike was left in the rack, the worse the brakes were next time I used it, requiring more blowtorch action to burn out whatever got in there.

I was away from home for a week with the bike and no issues, soon as I I got some and racked the bike for a couple of days the brakes went. The bike’d been to three bike shops for a remedy but they could fine nothing wrong and returned it with working brakes that went off again after a couple of days in the store.

Now I take the pads out when it’s racked and pop them in a polly bag tied to the bars, seems to do the trick.

Same here with my rear deore, small leak. Will be going to Hopes once I can afford a set.

Had the same issue with 2 sets of deores and one set of six. They were fitted to my commuter bike and I spend the first couple of miles getting them to bite. Next day they would be back to useless again. Never got to the bottom of it, changed to hopes in the end.

Leaky calipers here too. I suspect they didn’t like being stored cold; I suffered with squeaky, ineffectual brakes for a while when my bike lived in a shed, but swapping both calipers and moving it to a garage attached to the house has made the problem go away.

It’s only the rear brake, front is fine. Using Avid rotors but the combo worked fine for a year before the issues started.
Anyway I’ve order a replacement caliper (slx as it was less than £1 extra and has a bolt instead of pin).
Edit: Oops, I meant to post in my thread on a similar issue, still applies though

Anyway I’ve order a replacement caliper (slx as it was less than £1 extra and has a bolt instead of pin).

Will your brake hose still fit? I thought that the Deore had a compression fitting for the hose, and the SLX had a banjo? May be wrong… :-/

Will your brake hose still fit?

Oh arse, I hadn’t noticed that

I’ve tried boiling the pads, sanding them, spraying brake cleaner on them.

Cleaned the discs with brake cleaner and cloth.
Rubbed the discs with wet & dry paper.

Still the problem is still here. Brakes howling & poor stopping power again.

I’m going to change the brake pads yet again and see if it sorts the problem out.

The brake pads were all from the same batch. maybe the batch was faulty. Or maybe the area I was storing them (when not being used) caused them to be contaminated? After all there was a lot of oily rags in the cupboard and it is sometimes potentially damp. However they worked okay for the first few rides, if they were contaminated from storage surely they would have been poor from the very first ride ?

grannyjone – Member
I’ve tried boiling the pads, sanding them, spraying brake cleaner on them.

Cleaned the discs with brake cleaner and cloth.

Still the problem is still here. Brakes howling & poor stopping power again.

Wrap the pads in kitchen roll and see if there are any oil marks on them next time you get the bike out.

I’d bet there’s a small leak, I had the same thing and replacing the caliper fixed it. PITA.

I’ll try that and see

The thing is, this problem started on both brakes front & rear at the same time. Surely if it was a leaking caliper it would only be only one ? The chances of both calipers failing at the same time must be incredibly low.

I keep getting slighlty leaky shimano brakes- I replaced and cleaned/ heated lots of pads before I found the problem was slightly leaky seals. Diagnosed when oily residue found on the back of previoulsy pristeen the pads. Reaaly annoying. Have just sent latest set in to bike shop to be warrantied due to this issue.

This mainly happens on my fat bike that I ride on the beach- I uspect this is a contributing factor. Others in my area seem to have the same issue. It maybe a bad batch or a systemic problem, or just relate to salt contamination? Who knows.

Considering TRP SPYKE or BB7s to see if they survive beach riding better. It seems like they would. But who knows.

I get this problem on three bikes with a mixture of Shimano and after market pads (Superstar and Uberbike – obviously the Superstar ones will always have homicidal tendencies 🙂 )

I’m sure it’s something to do with oxidising or some other process on/in the pad material as they all come back to performance after a bit of hard braking and the bike that’s been left longest without riding is always the worst. I find I only have absolutely 100% performance consistently during a ride with some serious stopping required – e.g. recent trip to the Alps. And by 100% I don’t mean less than 100% is unacceptable, just that only when the brakes have been used hard do they give maximum power – potentially toward the on-off braking end of the range, which is what I prefer.

The chances of both calipers failing at the same time must be incredibly low.

It’s not a ‘failure’ per say – this is just the way that Shimano brakes seem to ‘work’ under normal conditions.

I’ve pretty much come to accept that all 3 pairs of XTR M988s I have ‘weep’ a small amount of oil over the pads over time. From what I have read about this issue – it fits with my sudden honking goose symptoms, which often occur after the bikes have been left standing for several weeks.

I’m pretty adept at judiciously cleaning everything down with alcohol and rubbing wet & dry – and bunging the pads in the oven if I have to. Probably have to do this once every 6 months.

I’m prepared to put up with this occasional inconvenience, given that when they XTR M988s are working they are utterly awesome brakes.

3rd thread in less than a month on leaking Shimano pistons/calipers..

STW Forum
STW Forum

IMHO it would appear that Shimano have a bit of a problem with some of their disc brakes..