Leaky shimano calipers

Do you think they’ll ever sort this out and/or admit it is a problem. It took them some time before they admitted the crank issues.

Just got my winter bike down from storage as I was doing maintenance rather than riding today. Front brake has no power and howls. Its bad enough that I can turn the wheel by hand with the brakes on. It was fine when it went away :(

It seems like the front caliper has gone the way of about 3 or 4 others I’ve had fail on various bikes over the last few years. Good mix level, road/mtb and how I use them.

The only consolation with this one is that the bike is 7 years old and did about 4 seasons of CX before being retired to winter road duties.

New calliper ordered, hopefully straightforward to fit. Not done shimano road before – either been in the shop or SRAM.

“down from storage” as in hanging with the front caliper higher than the lever?

I’d think you’ve had air migrate from the lever to the caliper in addition to any other potential seal issue

As @BearBack, storage might be the problem not the calliper. Sometimes a few taps on the calliper with a soft mallet and tapping the hose from bottom up whilst operating the lever is enough to dislodge the air without a full bleed, worth trying especially if there’s no obvious signs of leakage.

There’s zero power and it howls. Its definitely has all the symptoms of the leak. And it was stored in an attic bedroom rubber side down. The lever is actually “normal” enough in feel. No power means I don’t stop.

I’ve had identical symptoms with wheels that were hanging up in my garage – not even attached to a bike.

Could it be the effect of spider poo on the rotors?  It’s very difficult to clean off things.

I’ve had issues with Shimano road calipers. It’s definitely not a storage thing as the Hopes on the MTBs and the TRPs I replaced the road ones with have all been faultless, and are stored in the same way. Like the OP the decent bikes can be away all winter, hanging in the shed. In fact most didn’t come out at all last year due to long covid.

I was out the other day and stopped to chat someone who was packing up.”My front brake has died” he said

“Shimano?” I guessed

“Yeah, XT” was the reply, in a kind of resigned tone of voice, like he knew this was inevitable with XTs.

I’m at 12 failed ones through my family. Every single one failed after storage.
Had enough of them, I’m a big fan of Shimano drivetrains, but I’m not going near their calipers ever again.

Had same issue in storage but it was slight corrosion on the disc that then gubs/smooths the pads. Now ultra careful bringing bikes out of storage to not use the brakes until everything is cleaned up.

I’ve had similar symptoms on my hardtail recently after it sat in the garage not being used for ages.

No signs of leakage. I was thinking maybe the pads have absorbed moisture and/ or got general garage dirt on them. There not really anywhere locally that I can get enough heat into them to bed the in properly so I might get the blowtorch out and get sanding to see if it fixes it.

I’ve lost a few 7100 callipers to ‘leaky calliper’ syndrome & was starting to get rather frustrated about it. When the last one went someone mentioned cleaning them up & I realised just how grubby the inside of the calliper was (I tend to only clean up the insides when changing pads); it was the rear too, so subject to muck off the wheel.

I cleaned things up and used a cotton bud to clean around the pistons (after pushing them back in) and bizarrely it’s been fine since. I’m beginning to wonder whether moisture & crud/braking material causes clumping of material that might get caught under the seals lifting them just enough to allow some leakage. Totally anecdotal of course.

Incidentally, I’ve had the same tyre of callipers on the bike in storage and unused for months following heart attacks, and they’ve been fine when I got back to the bike.

I’ve also heard of leaky Hopes.

Shimano fanbois unite.!

I got rid of the issue entirely and completely across all my bikes by eliminating Shimano calipers.

Oddly and (unexpectedly according to the fanbois) I stopped with leaky calipers. It’s a Shimano issue

Fairly certain the seals are sticking to the caliper during storage and tearing when reused.

The caliper hasn’t ‘failed’. It just needs cleaned and reassembled.

The caliper hasn’t ‘failed’. It just needs cleaned and reassembled.

What’s the part number for the replacement Shimano seal that is required

It won’t need replaced, they’re extremely durable.

Quite a few different Shimano brakes across all our bikes and only had one problem that was caliper related.

Bought some seals off AliExpress and that caliper if also working fine now.

Sorry TR no part number for you but they were about a tenner for an XT four pot caliper and piss easy to change.

The Hope Tech4 V4’s on other bikes seem to require a lot more piston balancing than any of our Saint brakes so It’s swings and roundabout for me.

I’ve struggled to find seals there were some discussions on here at one point. Might not even be the piston ones if I remember?

I do know people see issues on storage. But the last time this happened it was on my commuting bike which gets used 5 days a week.

Looking at brake noise and I did see something about dirty calipers being a cause. Pistons not seating properly allowing vibration. It’s a different noise but I was going to look at my summer bike at some point and see if a good clean of the caliper helps. They get washed with the rest of the bike and a squirt of disc cleaner but I’ve never deep cleaned.

Never had a problem with the rivals on my CX bike. They alternate between an absolute hammering and being stored.

I’ve had pads that when I’ve put a heat gun on them oozed fluid.
There is definitely a problem.

Tbh I couldn’t give a crap anymore if it’s because they need taking apart and cleaning. Out of all the other calipers in the house (Clarks, Hope, Magura, SRAM, even Avid FFS) NONE of them ever do this. If I can’t get my bike out after 6 months storage and use the brakes without disassembly and rebuild with new parts, that’s nothing other than crap design/parts. Name 1 other component on an MTB that requires that amount of maintenance that _doesn’t_ have a crap reputation.

Like I say, I’m a huge fan of Shimano stuff, but crap is crap

Just need cleaning mate.

Cleaning right out of the house into the bin.

“Fairly certain the seals are sticking to the caliper during storage and tearing when reused”

Not a prayer.

The seal groove is contaminated with dirt ingress, water and maybe a little corrosion as a result.

If anyone wants to send me their “broken” calipers I’ll happily take them. I’ve got Shimano calipers that are maybe 15 years old and running perfectly.

It takes very little visible fluid leaking to cause contamination. You may not be able to see it at all. Sometimes the only sign is a slight build up of dust. I’m doubtful how much this has to do with dirt or storage given Shimano brakes with this issue mostly have it from new. At present I’ve got SLX and GRX brakes which have been fine left alone for 6 months at a time. But I’ve had Deore and various XTR sets that couldn’t be left alone for more than a couple of weeks. Merlin warrantied two lots of XTRs.

M8100 and M6100 here. Bikes in the house, not vertical. After 2 weeks, brakes had no power. Constant cycle of cleaning and bleeding. Thought it was environmental contamination from cooking etc. Covered rotors in plastic bags. No change. No oil residue on the back of the pads. Cleaning discs with ipa and running the pads under the tap scrubbing them together seemed to get them working again. Could it be the pad compounds? Any one had this issue with 3rd party pads?

I’ve Switched both to Codes Stealths no issues since.

My 8120 rear caliper leaks through the bleed nipple slightly. Got some replacement bleed nipples on order, hopefully it’s not the seat inside the caliper.

I’ve got Shimano calipers that are maybe 15 years old and running perfectly.

I’ve got a pair of them too.

But this is the newer ones.

I can’t put my finger on what is happening. It could be all sorts – such a as contamination while riding on a road, contamination on the car roof, dodgy cheap pads (although I’ve used multiple different brands and had same issues), storage, lube getting on them, then maybe the calipers or seals or pistons are somehow getting micro leaks.

All I can say is that I’ve had four sets of newer Shimano calipers and discs which end up with a fine black oily feel to them. Yet the cable discs, Magura’s and 2010 Shimano are all fine despite the same treatment.

Hot water and scrubbing pads and discs gets them back to good – for a couple of rides…

My summer bike is stored level and all summer I’ve been trying to get them to work like they did last year.

I just assumed I was remembering their power through rose tinted goggles , this thread makes me think otherwise.

Magoos mate. Can you give us a step by step of what needs doing?
I shall have a go on my summer breaks.

Hopefully my winter bike brakes are ok.

2xMT200, SLX M7000 & older M315 are all fine. Newer M6120 howling like a banshee.

I seem to be having more issues with the newer ones, particularly 6120 (I do have four of them).

Think I preferred the wandering bite point, which seems less of an issue these days.

But like the bite point, the annoying thing is that nobody really knows what’s going on, despite all the theories.

I’d be happy if Shimano supplied seal and piston kits, like other manufacturers. I’m quite prepared to accept eventually they need a full service. Replacing a whole calliper for the sake of a seal, pure waste.

At this years Mega I ripped a hose out of my Hope front brake during practice. I couldn’t get hose/fittings in time for qualifying so fitted a Shimano front and guess what? Fluid leakage at a piston, very slight but definitely there.
I had a pretty heavy crash on an easy corner, was it the brake? Dunno maybe I just ran out of talent at altitude.

Just had to fit 2x new Shimano Calipers to my Gravel Bike – its spent the last year or so sat on the Turbo Trainer in the house. Decided to start using it outside over winter.

Both calipers with failed seals, visibily pisisng oil out past the pistons.

I’ve never had an issue with MTB brakes (loads of sets of Deores), but the road ones are crap.

Like the OP – dragged the winter roadie out of the back of the cellar last week. Honky, non-stoppy front brake. Fortunately it shut up after dragging it down a couple of steep hills and normal service is sort of resumed (although the weather has got nice again, so more summer bike for a bit longer and  no doubt it’ll be un-cooperative the next time I try.

These calipers are the replacements for the replacements. Every other vaguely Shimano-brake equipped bike in the house (which have all also leaked) now has Hope RX4s fitted, but as its a first gen road-disc frame with post mount, I don’t want to spunk out on post mount RX4s, which will be worthless when I swap the frame for a flat mount/through axle one. (yes there are adaptors available but they’re a cludgy horrible mess and you can’t run a 140mm rear rotor)

My theory is still that there is water in the system (either getting in there during assembly or as part of normal use).  Mineral fluid being hydrophobic means the water just pools at the lowest point in the system which is often the caliper.

Then the water has time to do stuff to the seals.

Also note that with many shimano calipers it’s going to be very difficult to get any water (or anything else) out of one side of the caliper given the design. You basically have to turn the caliper upside down during the bleed.

I gave up trying to figure out how to make it work and just switched to DOT fluid brakes.

Also note that with many shimano calipers it’s going to be very difficult to get any water (or anything else) out of one side of the caliper given the design. You basically have to turn the caliper upside down during the bleed.

I’ve always wondered about the internal design of calipers, bleed ports and cable connections. Someone far cleverer than me could surely come up with a system which encourages fresh fluid into ‘good’ places and water, air etc out of ‘bad’ places?

I’ve always wondered about the internal design of calipers, bleed ports and cable connections. Someone far cleverer than me could surely come up with a system which encourages fresh fluid into ‘good’ places and water, air etc out of ‘bad’ places?

Shimano actually have this on some calipers:

https://bike.shimano.com/en-EU/technologies/component/details/one-way-bleeding.html