Whats up with my XT brakes?

How many shops use genuine Shimano brand mineral fluid every time I wonder, or do they use something cheaper?

Probably relatively unlikely as if they have to send them back under warranty and Madison/Shimano find non-shimano oil in them, they won’t warranty them.

I have used Halfords/Citroen mineral oil in Shimano brakes before but now use Shimano.

The Halfords/Citroen stuff is noticeably more viscous.

More viscous = harder to bleed.

Probably relatively unlikely as if they have to send them back under warranty and Madison/Shimano find non-shimano oil in them, they won’t warranty them.

Good point.

The brakes can have the same issue even if never bled or worked on in any way.

Seem to have achieved a decent bleed on my dodgy front Zee by pumping lever repeatedly and sealing top cap up quickly, but it still squeals like hell and lacks power.

Likely culprit for this is sticky pistons I think. Retailer has agreed to take them back anyway though.

Is this issue more prevalent in the M8000 XT brakes or just Shimano in general? I was thinking of buying some M675 SLX brakes due to how cheap they are now but think I might hold fire considering the amount of horror stories in this thread so far…

I have had a range of shimano brakes do this. Always much worse on the rear. Normally for me it has indicated that the piston seals have started leaking – I have had 1 set of deores and 1 xt warrantied (front and back) for this reason.

The double pull thing is happening at the moment but unusually there doesn’t seem to be any signs of a leak. I had just bought a new calliper rather than being without a bike for a few weeks but I am concerned that I will replace the calliper and find it has made no difference.

FYI I can bleed the working front perfectly every time but the rear rarely stays good for more than a ride or two even if bled hanging from the bars only.

If the problem more frequently occurs in the rear brake then presumably the thing to look for is any difference between front and rear brake. The biggest (only?) difference is the length / angle of the brake hoses – the front being shorter and more vertical. Does anyone else clamp their bike in the frame so the rear hose is as near vertical as possible before bleeding? The few times I’ve done a bleed with the Epic Bleed kit I do this and give the hose a good tapping all the way up. I don’t know if that would help – but probably worth a try and it will do no harm.

The truth is there is no technique or trick for bleeding Shimano brakes that people are missing. In fact lots of people are going way beyond what is required to ensure a great bleed. Sadly Shimano brakes are flawed by having this major issue along with poor bite point control and not being small part fixable. You would think they would have sorted all this out by now.

I agree that bleeding isn’t the problem. Air in a brake system just doesn’t cause this very specific problem. People are getting them working after a bleed, but it normally involves pushing the pistons to where they should be for the current disc thickness/pad wear and over filling the system, which will work until the pads wear down a tiny bit, then back to square one, the pistons aren’t realigning themselves.

Why it is more common on the back than the front who knows. Maybe because they get hotter which pushes fluid out of the system back into the reservoir, which can’t then get back into the system properly, doesn’t quite seem right because the pads haven’t gone any further back. Or maybe because the pads wear quicker it happens more often so is more obvious?

New pads and thicker rotors are just temporarily hiding the problem imho.

Am about to hit ‘buy’ on a set of Hope X2s, that should solve the problem! 😆

Pads wear quicker on the front though.

As far as I know, these issues only seems to have started with the 785/985 brakes and are now continuing with the 8000/9000 range.

I can’t believe what a minefield I opened up with this thread. I was expecting quite a straight forward answer, not the consensus that this is a widespread problem with no real solution and nobody really knowing exactly what the cause is!!

I’m sending mine back to CRC to see what they say or do and if there’s any useful information from this ill post an update.

^edward2000

If only someone from Shimano read this! Madison have been good to take a look at mine and will let you know what they say. The only way they might acknowledge there is an issue (and with this many people having issues i cant believe its just incompentence of bleeding) is if everyone sends them back. I am changing as i just dont feel safe using them currently so I’ll see what they say…

In worse conditions (where more mud/grit is being thrown onto the rear disc) or when you’re brake dragging rear pads often wear quicker than the front. When it’s drier and/or you’re braking with better technique the reverse tends to be the case. Also depends on your tyres and rear suspension.

Having exactly same problem as well.

Is this only happening on the “UK” set up ? or a there riders on the continent moaning about their front brakes.. zut alors zis shimano est merde etc etc

Pads wear quicker on the front though.

Depends where you ride and in what weather. I go through rear pads 3x faster than fronts due to a lot of wet riding (puddles as well as in the rain) kicking up the grit and sand onto the rear caliper and disc chewing up the pad. The front doesn’t get anywhere near as much crap on it so the pads last a lot longer. In winter I can still get away running softer pads up front (uberbike semi-metallics are my go-to, nearly as good as the Rahox ones but significantly cheaper!) whereas I need to go to sintered on the rear to not have to change then every ride or so. Go through rear discs faster too. Been the same on my Shimano and Hope brakes.

I currently have 3 sets of Shimano brakes (2x Deore, 1 XT) and they all work fine. I did have to bleed the rear XT a few times to get all the air out of it initially (on my 5 so hose off to fit) and found standing the bike upright really helped. One thing I have noticed is that Shimano pads are noticeably thicker than aftermarket ones, could this be a problem? I found the OE ones stopped working once they’d worn down to the end of the chamfered part of the pad so you’re not getting any more useable pad depth but maybe the caliper is set up to use thicker pads and this is causing issues? If it is maybe fitting some of the aftermarket fins would space the pistons out further, sort of simulating the thickness of OE pads.

If the XT’s show any sign of playing up I will be going back to Hope. Only switched to XT as A: my rear Hope was old and needed upgrading to keep up with the front and B: I was fed up of constantly having the wrong spare pads in my pack (Shimano when riding the bike with Hope and vice versa). It was cheaper to switch one bike from Hope to Shimano (actually made cash 😀 ) than put Hope on the other two bikes!

After reading all this I’m keeping my fingers crossed as we haven’t experienced any of the problems and are running eight sets between us.

Well, today I went to swap my rear pads and noticed a stuck piston. My attempts to press it back in resulted in a cracked, leaking piston.

Just got a new 800 caliper and lever from lbs as I need it for tomorrow.

May explain the poor performance on that set.

I can’t believe what a minefield I opened up with this thread. I was expecting quite a straight forward answer, not the consensus that this is a widespread problem with no real solution and nobody really knowing exactly what the cause is!!

Errr, perspective required, please. I haven’t bothered to count the number of individuals who have posted on this thread, but let’s take the number at the top of each page, which says 68. Now, before starting a zombie shimano brakes apocalypse, I wonder how many units have been manufactured in the last 4 years or so? Hundreds of thousands? In percentage terms, possibly acceptably small enough to warranty.

Of course, there is the possibility of death, at which point my perspective plea falls somewhat short and I just hope the tabloids don’t get to hear about this epidemic.

Internet eh? 😉

P.S. Stealth edit 😉

OK but its not that as my little bottle says “Shimano” on it. Not that other mineral oil would behave any differently.

Shimano brakes HAVE to have shimano fluid in them. It’s a propriety fluid. All ‘mineral’ fluids are not the same. It affects the seal performance.

Just to add some more food for thought, mine started to do it when I took the wheel out and put the bike in the car on its side.When I put the wheel back in I had to pull the lever a few time before it went hard, which is fairly normal as the piston could have been moved back whilst taking the wheel out. But the other day on very bumpy down hill the lever went to the bar, I did the run again 3 times and everytime on teh same drop it went to the bar!

Maybe it has something to do with the fuild level in the lever. Anyway I have now bleed it and cleaned the pistons, we will see what happens.

Hi all, I had the same issue and sent them back to the online retailer who in turn sent them back to Madison/shimano. the seals on the piston in the lever were dodgy so would release the brake pressure a few seconds after pulling the lever.

They were replaced within two weeks, so I think Madison/shimano know the brakes are poorly manufactured.

The term mineral oil is like engine oil. Loads of different component mixtures, for example cyclo mineral oil is definitely thicker than shimano fluid. In that article on the first page im pretty sure there’s a table with a boil point temps on it and shimano claim their BP is a lot high than bog standard mineral oil or even royal blood.

Is it just this/last years Shimano brakes that do this?

Are deore brakes problematic?

I have some Avids that I was going to swap for Shimano…

I have my Hope X2’s for sale because I wanted to buy some M8000’s.
I’ve never had a bad set of Shimanos and I’ve had few sets of Deore/Slx.
Think I’ll keep my Hopes now though because aside from the length or shape of the lever they’re ok for me and my riding.

I have SLX and no issues, the XTs are not the same. For all those that insist on saying it must be the bleed etc, do be brief – i do nothing different between the slx and xt yet the XTs are so inconsistent they are dangerous. They have gone back to Madison. The latest mbr also refers to inconsistent bite point for a set of XTRs, something is wrong somewhere.

I’ve had a few sets of Shimano brakes and have generally found it easier to get a good bleed out of my Deore’s over the posher ones. My XT’s were powerful but I was never ever able to get a good solid lever feel and not where the shop I bought them from. My Zee’s are easy to get set up well and seem consistent as we’re both pars of Deore brakes that I had. My current XTR’s may well be going back because they were pretty inconsistent on Saturday.

I think the new bleed process is more of a ball ache than it was on the early Shimano brakes. They were so easy to bleed and my original Saint brakes always felt great.

How many people are getting filthy black contaminated mineral oil out when they bleed?
When I have had this, it’s usually coincided with the onset of inconsistent lever feel.
I can only speculate that this is from a seal that’s deteriorated.
As it’s evident at the lever end, I suspect it’s the piston seal in the lever.

How many people are getting filthy black contaminated mineral oil out when they bleed?
When I have had this, it’s usually coincided with the onset of inconsistent lever feel.
I can only speculate that this is from a seal that’s deteriorated.
As it’s evident at the lever end, I suspect it’s the piston seal in the lever.

Yep – totally black after just a few weeks – although I’m voting for caliper seal

sorry to resurrect this thread, but after boldly claiming mine only do this when the pads are soon to die, the rear has been doing on newish pads on every ride for the past couple of weeks, creating a near death moment at wharncliffe today.

the consensus seemed to be that it was mainly a rear bake problem and likely due to the pistons not auto adjusting due to the seals. has anyone swapped a previously dodgy rear caliper with a working fine front caliper on their bike to see if it is a rear specific or a dodgy unit issue?

just trying to eliminate possibilities before i buy a new caliper (will do my usual overfill bleed first, but as that what was done last time not holding out much hope)

Don’t know, but that would certainly narrow it down to lever or caliper sofaboy, 2 year warranty you know?

Don’t know, but that would certainly narrow it down to lever or caliper sofaboy, 2 year warranty you know?

weren’t bought as a complete set. currently saint levers on zee calipers (both under 2 years old) as smashed up the original zee lever assembly in a crash. not sure they would warranty a hyrbid set up, further complicated as bought from different online retailers. frustratingly i can’t remember if the original full zee set up suffered from the same issue

very keen to sort out as today was very close to a face tree interface

I have been meaning to swap my front and rear calipers round to see if that moves the problem to the front, but haven’t had a chance yet. I have also been meaning to try and send the back off for a warranty job, but that would leave me without a brake, which, as bad as the brake is, it’s better than nothing. I could borrow my wife’s back brake (xt working fine) but she might notice.

I did try over filling the system, which was fine for a while, but muddy sandy riding meant it wasn’t long before enough pad had worn down to bring me back to square one again.

What a pain this all is.

tombon – Member
I have been meaning to swap my front and rear calipers round to see if that moves the problem to the front, but haven’t had a chance yet.

if you do, let us know how you get on. i was going to do it myself, but the waters have been muddied by having a hybrid set up (saint levers, zee calipers) and i can’t remember what the original set up (zee’s at each end of the hose) was like

I’ve had a set warranted full of green Citroen mineral oil.

Fed up with my rear XT and dropping wheel out to pump pistons out to allow for pad wear! Tried bleeding but still comes back. Just ordered Hope E4s last night!

So far, fingers crossed, my new XT M8000’s have been rock solid. Only one ride on them mind…

I had to shorten both font and rear hoses, pumped the pistons out before I did it.
Currently very good and solid but we’ll see innit.

For what its worth i have just blead up the rear brake on a Kona process (third time lucky)and seem to have got a much better lever, I put the bike in a upright position so that the lever is at the top and caliper directly below,then i fitted a rockshok blead kit syringe (with o ring) into the lever/resevoir, Yes they fit!,After a while,and by tapping on the hose and moving the lever up and down on the bar small bubbles started to flow into the syringe followed by a bigger one.The lever felt much better straight away,having the rubber O ring on the resevoir is key here as its a visual guide to releasing trapped air.

Try a bit of logic. If it is mostly a problem with rear brakes then you can eliminate anything which front and rear brakes have in common otherwise it would effect both equally. As far as I understand it most of the equipment (seals etc) front and rear is the same. Do rear brakes get more crap and contaminants than front? Possibly but is that enough to account for the difference frequency of rear brake compared to front. It seems to me that the biggest difference is in the length of the hoses and, if brakes are bled in situ, the more horizontal run of the rear compared to the more vertical run of the front and maybe the orientation of the calliper. So orienting the bike so the rear hose is as vertical as possible (or removing to do the same) and giving it all a good tapping is likely to be a good plan. I’ve never had a problem with XT on two bikes doing this.

I had some XT M8000s. My front was worse than the rear – even from new before hoses were shortened. I bled about 5 times (with Shimano oil) including leaving overnight with lever tied back to bar etc…none of it worked. Have older shimano’s on our other bikes which have been bulletproof. Madison warrantied…got a refund … now have Hopes which are spot on.
Shame…been Shimano fan for over 20 years…hey ho.