You can't replace seals on Shimano brakes, if the seals are gone, you will have to replace the caliper.

My rear Magura went off yesterday co-incidence of
coldest commute yet at -11. No oil to be seen but lever is pulling to the bar, pistons are moving. Never had an issue before. Strange.

hmm, i've been doing some cold riding recently, the lever-action feels ok-ish, but definitely 'different'...

and last night the front brake started behaving like i'd got a little oil on the disc.

i thought i'd been careless with the spray lube (i was very carefull), but now i'm looking at my brakes with suspicion...

You can't replace seals on Shimano brakes

donk its the fluid shimano use (not dot type brake fluid its a mineral oil) - it thickens up in ythe cold and feels like your brakes are pumped. its a bit like if you leave a jar of olive oil in the cold it goes cloudy and starts to solidify, not a great description but thats the idea
on the plus side its not nasty like dot brake fluid
g
no dought someone will be a long soon to tell me I'm wrong

i won't say you're wrong, but there may be something else going on aswell.

i use citroen mineral brake fluid - i'm sure that cars are ok in the cold, so why not my brakes*?

my guess would be that the rubber seals in the callipers are acting up, contracting, stiffening, a combination, whatever.

i confess i've just been reviewing my policy of avoidance regarding hope brakes...

(*it's entirely possible my brakes are fine, that they feel 'odd' because my hands are cold, and there's oil on the disc/pads because i'm a slapdash moron with the spray-lube)

You can replace them but you can't buy them from Shimano as a separate item.

I've had decidedly wooden braking feel in the snow but also have had iced up discs after long pushes in very deep snow then short bit of riding then pushing again.
Then again it could be fluid...

You can replace them but you can't buy them from Shimano as a separate item

bump

Another set of Shimano brakes...

I'm sure they are a standard item that could be bought from a specialist seal supplier but I've not heard of it yet.

I'd be very interested if anyone found out and I will look into it when one of my sets become inoperable.

You can pop the pistons out and clean out the inside but obviously you run the risk of damaging the seal. I've done it on one pair that had lazy pistons and it worked fine.

closer inspection reveals that my front disc is now covered in oil.

there's so much there's just no way i put it there when i was carefully oiling the chain.

i have shimano-brake-callipers-going-a-bit-leaky-in-cold-weather disease.

dammit.

this is a seal thing, not a fluid thing.

the brake that is affected is several thousand years old, i will swap it with another, newer brake, and see what happens.

although right now a set of hope brakes is looking tempting - anyone got a set of mini's for sale?

I've got a mini front 180mm you could purchase - thats a mini not a mono mini 🙂

When I get a chance I'm going to clean it up stick a spacer in and pull the brakes on pretty hard, check for leakage. I'm hoping it's a temporary problem ie they stiffened up in the cold and leaked, once a bit warmer will work fine.

I haven't removed the pistons completely before, I normally push them out a bit more than usual and wipe/clean round the piston with min oil/dot depending on the brake then push back in.

Is this a problem with certain models? certain vintage? certain "milage"?

I think its worth collecting a bit more data on the problem.
Quite happy to start the ball rolling.

I've two bikes with shimano brakes:

Model/Age: 2009 XT fitted from new on FS and 2010 XT OEM retro fitted to HT.
Usage: Both heavily used (gone through umpteen pads)
Fluid: Both recently bled through with Halfrauds LHM
Maintenance regime: pistons lubed with plumbers' silicone spray and cycled in-out when changing pads or at any indication of lazy piston.
Stored: Integral garage, so only exposed to extreme cold when riding.
Location: Lancs.
Cold use: Still night riding, well below zero.
Cold effects: both feel a bit more digital on-off at the moment(Hayes like) but continue to work fine. No leakage. No problems yet.

For DONK
Model/Age: XT iirc fitted on one of his bikes he has so many - did you see what I did there?
Usage: Both heavily used (gone through umpteen pads)
Fluid: Probably proper LHM shimano stuff
Maintenance regime: pistons lubed with plumbers' silicone spray [ well he would if I did not have it at the minute] and cycled in-out when changing pads or at any indication of lazy piston.
Stored: all throughout his house in every room
Location: Lancs - well near enough eh
Cold use: Still night riding, well below zero.
Cold effects: BROKEN 😥

How well did I do ???

junkyard, I wasn't having a pop at DONK or suggesting he'd done something wrong. I just wondered if there was a common factor such as model/year.

i dont think it is the fluid. my 2008 XTs feel pumped up - the pads are closer to the disc too - makes riding a lot harder work. However my SLX brakes work just the same as normal on another bike, so i doubt it is anything to do with the fluid - both bled with shimano oil.

I contacted madison about this last winter and they simply replied with links to the shimano bleeding instructions. When i have some time i will do a bottom up bleed of my XTs to see if this helps, but at this rate it will be next winter before i find out 🙂

This might make sense, as the SLXs came as a pre bled set, whereas i had to put the XTs together myself.

Just found some threads on another forum from USA users (proper cold) that seem to suggest it was a 2008 models problem and more recent stuff hasn't suffered the same. Just anecdotal, nothing conclusive.

It's ok ecky junkyards post wasn't aimed at you, just having a joke with me.
He got most of it right, XT late07/early08, as I mentioned I use brake fluid rather than silicone spray when lubing the pistons. Otherwise what he said.

What Matthew said (and I think other people said similar in other threads) suggests shimano may have changed the seals and newer brakes aren't affected.

EDIt just read that post ecky, looks like I was right. Did it say abnything about even older models? I have a pre servowave xt, 2006/7ish.

yes sorry Ecky I ride with DONK- digs were all at him
fitted on one of his bikes he has so many - did you see what I did there- it is from his on one for example

Do you ride round with your eyes closed junkyard? the on-one has magura rim brakes, the ragley has xt discs!

🙂

Hard to tell from how far away I am 😳

Another vote for not the fluid here. My g/f has 2 pairs of m525s that are faultless whereas my m535s have.been ****ing rubbish!

My 2008 XTs have been odd recently too... I've rebled both brakes on mine recently because the levers were getting closer and closer to the bars in just a few days, despite them having been fine for ages previously. I've been using this bike as the commuter recently, so it's in a garage overnight and outside for most of the day in minus whatever.

There's no visible oil anywhere and the brake power hasn't changed throughout. I await to see whether they deteriorate again...

My LX (2008 as it happens) do this all the time and have done since new. They do it all year though, but certainly worse in the cold. I'm deeply fed up with weekly wheel-out and clean/exercise/lube the pistons. Without that (or even with that), they just touch-skim the disks all the time, and make the most awful high pitched strangled cat ringing which drives me nuts.

'99 XTs and my rear has been weird during the snow. Lever is rock solid, brakes are on/off with no modulation. Seems to be almost back to normal now it's warmed up a bit.

Front has been fine though. I had assumed it was snow and ice bunging up the calliper.

Original Saint - yesterday - all the fluid pissed out the seal when I pumped the lever when the bike was stationary. Cue one distinctly challenging ride home on the road and iced up trails. I pumped the lever when I noticed a small puddle of pink fluid in the snow. Previously, the brake had started to pump up in the cold. Think I'll contact Madison to see what they say about it.

10 of us have just had 3 days riding in the lakes. Minus 11C to minus 6C all the time.

The only brake issue whas when I went over the bars coming down from Carron Crag (My front wheel got stuck in the only bit of mud within 100 miles) and it pulled the piston out of the lever of my original Hope Mini. Took at least 3 minutes to fix it.

Most of us had squeally brakes but nobody's stopped working.

i would be interested to hear what Madison say. I got a reply with bleeding instructions when i enquired about why my brakes went odd in the cold.

For info, last time I rode the bike (new Saints) the front was ok, the back was very noisy and on/off braking

I just went into the garage to check the bike, the back one is almost locked with little to no lever movement, the front one is free but with very reduced lever travel....no leakage

I've brought it into the house, lets see what happens when it warms up

the back one is almost locked with little to no lever movement, the front one is free but with very reduced lever travel....no leakage

my xt's have done that a few times - have always been okay when they have warmed up. If it's well below freezing I now use the FS bike, which has Hope Mono Mini's, which so far have been fine

sanny, if your brake is pissing fluid then it sounds like the seals more than stiff. Perhaps its just torn / split due to the cold or old age perhaps?

my xtr brakes have been acting up sumthin shocking lately too, squeeling and very spongy (doing me flaming head in) 🙁

No problems with mine last night (cold enough to freeze my beard!) , if anything they feel great, much more solid, which is how i'd like my brakes, minimal lever travel, then no more movement please!

just wondering - if they sit unused at sub zero, will the seals suffer, or will it only be through use ? Curious as my garage, although integral, is baltic and bike sits close to the door, so air around front brake consistenly probs between -5 and -10 last few days. haven't used that bike in over a week, so expecting that if brakes remain untouched nowt will happen and they won't start pissing fluid all on their own.... ❓

it was -6 here last night (at the warmest part of the ride - under the trees).

my SLX brakes were/are fine.

my hone brakes were used on a friends bike - they seem fine.

my deore brakes are also unaffected.

so far, it's only my lx brakes* that have gone a bit 'funny' and then leaked oil over the pads/disc.

(*circa 2007 as a guess).

i would hazard another guess that if your brakes are from 2009/2010, or deore, then you don't need to worry...

ahwiles - my older XT's did it, they were 07, lever went hard, virtually no travel, minimal power, but never got to the leaking piston stage. My 10 XT's are exactly the same, although again not had the leaking fluid, just weird lever feeling

hmm...

(scratches beard)

I had some 2005 deores on my bike till summer. They survived plenty of winters. They felt wooden in the cold but still worked. They went back to normal when they warmed up. Current SLX do it now.

Sounds like you've been unlucky or have another problem where the stress of the cold has caused failure.

Original Saints (I think) basically the same as the XT's of that era. 1 piece 2 piston caliper.

Fine last night at around -5. Probably a bit less lever travel.

Stored in a garage which isn't freezing but not warm either.

shimano has a known problem with their seals leaking in cold weather, for me it seems to happen in very cold weather 10-15 degrees.
Shimano has replaced 3 xtr calipers for me so far. the warranty for xtr is 3 years, 2 for xt, theyve allways included new pads as well since the old ones are oily, make sure you sand and clean the rotor

supposedly they have fixed the problem but I havent had mine that cold yet. should know this season. my older xt (05?) also have started leaking. so since theyre on a pugsley Im replacing them with BB7s

That makes sense. I thought something had gone wrong with my front brake (pre 06 deore) when it pissed oil all over the floor through the piston. Hasn't affected the rear brake of the same vintage though. Will a rebleed fix the issue, or do I need to think about looking at a new front brake....?

I [url= http://www.singletrackworld.com/forum/topic/freezing-temperatures-and-shimano-hydraulic-disc-brakes ]posted about this[/url] a while back as my LX M585 were playing up horribly and did the same last winter (although they survived and worked well for the rest of the year). I'm not sure about the oil thickening, the general concensus seemed to be that the rubber in the seals hardedens up. With each succesive pull on the levers the travel reduced until there was virtually none and the pad were in contact with the rotors (not enough to lock the brake but more than enough to be really annoying). When my brakes need replacing I'd be interested to know if there are any Shimano models that don't suffer this.