My front brake is now awful. It starts off ok but by the time of full braking it feels as if the calipers are flexing. No bite and no chance of stopping.

Swapped disc,fluid and pads . Still bad.

A look on the web shows lots of broken pistons.

If it was leaking how much fluid would I see?

I’ve covered them in talcum powder ,put the bleed block in and given them a good squeeze.

Can’t see any damp powder anywhere.

Any thoughts?

When mine went it didn’t take long to notice the oil on the caliper.

Levers can leak too, and the seals collapse.

It’ll either have a micro leak for the caliper or you’ll have an issue with a piston in the lever most probably.

I’d just buy a new one to save a lot of faffing about – it’s ultimately what happens to quite a lot of Shimano brakes. Which is why my mtb’s don’t have Shimano brakes on them.

That said I do have Shimano hydraulic road brakes as they came on the bike I wanted – they haven’t failed yet! These is a Hope caliper that is compatible with Shimano road brake systems though so when they self destruct that’s what I plan to replace them with 😃

I guess one bad brake in 20 years isn’t too bad.

Shame it’s an expensive one!

They can leak between the two halves of the caliper too. I didn’t see much fluid until I had it in bits. I’ve had two go (and some SRAM ones) and, same as you, tried everything and nothing fixes it.
Easiest fix is new brakes. Never had trouble with hope’s but I did get some cheap zees for a bike I don’t use often.

Did you buy new? If you did ask the shop about recalls and/or warranty.

Brakes are years old. Are the 4 pots more robust?

I’ve got both. I’ve had to bleed both, and be patient doing it (quick bleeds have been worse than useless – there’s always air left in the system). Two pots have been good for about four years (touch wood) and have been bled twice, but I’ve currently got an issue which appears to be a sticky brake lever on the rear 4-pot. Looking at it this weekend.

Might stick the rear caliper with the front lever.

Should be able to work out which bit is bad that way.

Got home and gave them another squeeze and fluid spurted out of the round bit with holes in. Never noticed a leak from there before.

You need to check the diaphragm in the reservoir, for that you will need to remove the lever from the bars, push the bit to open the lever up, then you can see a small grub screw that takes a torx key to remove, when you do this you can then remove that circular bit which has the diaphragm.

From there check the inside of the rubber, make sure it’s all good, clean it up, refit it (quite easy, only goes in one way), then reassemble and rebleed the lever.

Not sure if it’s a bad photo or if your lever is in a right state. Just buy a new brake – not worth messing about with. You could replace the lever now, but the caliper is then a ticking time bomb

Got home and gave them another squeeze and fluid spurted out of the round bit with holes in. Never noticed a leak from there before.

Was just going to post what argee posted.
It’s meant to leak if the port is blocked… when did you last do a complete bleed and clean?

Last bled yesterday. It looks a state as it’s covered in talcum powder!

Wiggle had a complete brake for £66 , so gone with that option.

Good choice, use that one as spares now, can even do that strip of the lever to just get an understanding of the lever

Last bled yesterday.

and before that?
What colour was the oil when you bled it?
Immediate issue is likely a block in the port as Argee posted… the newer levers have the pressure release you discovered… (shocked the hell outa me when I found it by accident… but its worked for years after)

longer term though if you don’t do full bleeds the dirt gets behind pistons (especially the master)… once that build up to the point it stops working you’re into a world of pain. (unless your idea of fun is even weirder than mine)

can even do that strip of the lever to just get an understanding of the lever

Or … Dry it out so the piston shrinks and clean it… leave it a while and repeat…keep going till you don’t get bits of black gunk.. you will be amazed how much gunk gets behind the master cylinder.

@stevextc are they really meant to leak? Not saying I know otherwise, just been told different. I was told the diaphragm was to allow for expansion of the fluid but not supposed to let it out. I had one squirt when I pushed some pistons back while forgetting to open the bleed port and was told I had popped it.

@Jordan

Hmmm… given brakes are an important safety item I’ll reword that.

I haven’t read the documentation or stripped a x000 series lever yet. (good sign I haven’t had to)

I did however squirt a load out a long time ago now when the x0000’s were pretty new.
MY first thoughts were “oh bugger….” but I cleaned it up and it’s working a couple of years down the line so I’d assumed the “new dimpled bit” is actually designed to work that way.

@stevextc yeah, I had a look at the documentation and couldn’t find any mention of it. Would be interesting to know for sure.

Funnily this thread did make me do a strip of an xtr lever i was saving for another build, there really isn’t much inside, the diaphragm/bladder attaches to the circular plastic plug that you can see the end off (which the oil can come out off), only way the oil will come out that port is if the pressure to push it through the piston is greater than the pressure required for the oil to push past the diaphragm into the plug and shoot out as you’ve seen.

A strip is always good, dust/dirt/etc can get in over time, pretty easy to strip down, it’s just a faff working out where the two grub screws are, one of them is hidden behind a little rubber bung, but needs to be removed to get the lever off.

@argee when you say that the oil can come out of it, do you mean there is a legitmate way for it to come out without it being damaged?

Yeah, it’s all about the pressure in the reservoir, if something is causing a little more issue with the pressure required to work the piston, then it will build it up internally, below are a couple of pics of the internals that i had from the strip/rebuild.

download high quality pictures from instagram

download high quality pictures from instagram

OK cool. Cheers for clearing that up!

Just had exactly the same thing happen with that spurt of excess fluid coming out of that port on the end of the reservoir – mine happened as I had overfilled the system doing an interim bleed on half worn pads, then decided to do a full bleed with new pads and got that shot of fluid coming out when I pushed the pistons back. Wasn’t expecting that.

This seems to be the most useful thread with pics about thanks.

Just to confirm with those that know about this – If you’ve had a bit of excess shoot out there..is it safe to continue using the lever, like it was designed to do that? Or do I need to pull it apart some more an d replace diaphragm? Lever feels OK for time being.

Cheers.

I’d just keep an eye on it, realistically it’s coming out the hole to reduce the pressure on the system, as well as some oil being in the diaphragm, i’ve never seen the issue affect the brake, you may have to top up the reservoir a little at some point, but that’s the basic remove cap, pull lever and do a mini bleed.

The worst part of this is that it looks a lot worse than it is, making you worry, but as always, only worry if it’s becoming spongy, as that’s the sign air is in the actual system (hose/caliper), not just a little inside the reservoir.

Thanks your photos are really useful. Do you think the oil escapes around the edges of the circular end of that long rubber bit (maybe an o-ring can’t quite see) for it to then to shoot out the centre of the plug?

Just wondering how likely it is to blow the rubber sealed on the end of the long section (not sure what to call the long rubber bit, is this the diaphragm?) – if it’s a few mill thick I guess thats unlikely and fluid will just go around the edges then rubber will reseat itself.

Thanks.

Not much chance, it’s the plastic end bit it seats on, i dare say the diaphragm is design in this way to allow a certain pressure build in the lever to allow the oil to leak out a little, otherwise you’d end up with the brake locking on, it’s similar to the air holes that were in (are in) a lot of other brakes, just that this one is horizontal rather than vertical.

Oddly my rear brake started doing the same at the weekend – I’ve bled it to within an inch of it’s life and it’s not much better. I’ve cleaned and lubed the pistons which all look fine and not leaking.

I’m pretty convinced it’s something in the lever. Initial pull has the lever back to the bars with minimal pad contact, but after a couple of quick succession pulls the bite comes back. Then 30 seconds later back to the bars 🙁

Next step is to rebuild the lever I think.

That seems consistent with the very common problem these brakes have especially the generation from around 4 years ago, which could be from inconsistencies to the internal surface of the lever. Google seems to throw up about 4765 similar stories…

Mine bleed up fine and feel perfect at the lever…then after only a few rides they seem to let a bit of air in again, which seems to be another mystery with no obvious leaks.

From the picture above of the reservoir end cap; I’m surmising that the fact that excess fluid shoots out that port, that this is the same mechanism that allows air in to the reservoir to compensate for the loss of fluid as the pads wear – and that the small size and shape of the reservoir explains why its so important not to pull the lever when the bikes upside down or on its side, as when on even slightly worn pads this could easily introduce air into the line.

Just did a full lever rebuild with the help of this video, much easier than I thought, and now I understand how the lever works! There was lots of grime in there, and the master cylinder felt a bit worn to the touch… I’ve reassembled and hoping it’ll make a difference.

As above, it’s like anything else, you need to give them a clean and check now and again, i usually wait for an oil change on the system to do it, just a little bit of dirt can cause issues, air getting in is the same as all other brakes again, i don’t think there is an airtight braking system out there, if there was it would be a nightmare to operate properly through all temperatures and usages.

All in all bike brakes are pretty basic hydraulic systems, and all pretty much work on the same principle, you use a lever to reduce the volume and increase the pressure in the system, anything complicated on it is to give you feel and movement at the lever.