So, my 4th set of Shimano calipers to fail. They are older XT M785s, so I’ve had 3 x SLXs fail and now these, all different bikes. I’ve replaced them with M615s which I’ve had no problems with. But, just looking at prices and the seemed to have doubled since I last got some. So I’m thinking just replace the calipers with some new SLX, I’d replace with Deore but the hoses are different fittings so it would mean calipers, hoses and fittings. So are the new SLX calipers ok now or still prone to problems. Also trying to see of I can get a Deore brakeset cheap and then I could use the calipers and hoses to connect up to my XT levers – anyone know of any good deals for a set?

It’s a bit of a lottery…
I have twin pot SLX brakes on my Kinesis and they’re perfect. Definitely no leakage.
Don’t know of any deals. (maybe – https://www.lordgunbicycles.co.uk/shimano-slx-bl-m7100-br-m7120-i-spec-ev-d03s-organic )

Are there any signs if they are leaking.
Am accumulation of dust on a join?

Are there any signs if they are leaking.
Am accumulation of dust on a join?

They leak round the pistons. And the main sign is a HOWL

Had a MT500 go this week – pads wet with fluid. S/h bike so don’t know the history but very few miles judging on overall condition.
So I’ve taken the definitionally insane step of ordering a replacement slx set from merlin at £150.

One problem I have is that I had some avid elixirs about 10 years ago that I just despised, so I swore off them. I’m sure they are different brakes now – everyone says the codes are good for bigger bikes, IDK about the others. Honestly I struggle to make the switch – I like the performance and feel of shimano and they are great to bleed – just these blooming caliper leaks happen time after time.

Never buy second hand shimano calipers – warranty on shimano brakes as purchaser is generally respected because it’s such a known problem.

I’ve not had any leakage with the M7100 callipers either.

I had to replace on recently after managing to crack a piston and got one from Tweeks for £28.

https://www.tweekscycles.com/uk/shimano-slx-m7100-2-piston-caliper-madbrm7100fr/

So I swapped out some leaking Deores on my son’s bike for some highly-regarded Clarks M2 (aka I Can’t Believe It’s Not Deore). At that price they’re an absolute steal.

However, it appears that they copied Shimano too accurately, as the rear brake is a bit howly and appears to be microleaking… Luckily this is 11 months in, so a warranty replacement caliper arrived this morning.

The common consensus seems to be this problem is due to corrosion at the base of the seal groove that houses the pistons judging by forum results.

My zee’s both started leaking recently. I’m planning to have a go at cleaning out the corrosion and hopefully they’ll not be too badly damaged and can be used again.

The fundamental design of the calipers hasnt changed I don’t believe so if the calipers aren’t cleaned properly post ride and given the opportunity to dry out relatively quickly this problem will happen again and again.

I wasn’t looking after them properly so im taking responsibility on this one i think.

Are road calipers also affected?

Again, judging by the posts ive read road calipers seem to be just as bad if not worse due to road salt and frequency of use.

I don’t ride road so couldn’t comment myself.

I’ve replaced a 105 caliper – replacement has been on the bike for a couple of years with no issues though. Total lottery!

Are road calipers also affected?

The Tiagra caliper on my gravel bike has failed…

105 on the rear of my road bike microleaked after a couple of years so got replaced with a Hope RX4. No problems since.

They leak round the pistons. And the main sign is a HOWL

Are we sure about that ?. As a few months back i read a link to a  forum post, that talked about the leak is coming from the oil transfer port, something to do with the O ring not sealing well enough.

It was being claimed that the o ring doesn’t sit high enough so when you close up the 2 caliper sides, the o ring doesn’t compress enough.

The rear on the Ebike has the prob, pretty much non functional and as im swopping them to Hope V calipers, I thought I’d dismantle the duff one to see if i can confirm as to where the leak is exactly.

I reckon when i split the caliper, if the metal that is normally sealed up is wet, then its possibly the port as the port is in the middle, but if its dry, then fluid is coming from elsewhere and that could be the pistons.

Possibly.

Although eldest_oab had a 2021 XT lever main seal just blow – and according to the shop, they have seen a load come through that are the same age with the same problem….

Four year old XT/SLX; many thousands of miles, only ever get cleaned during the once-a-year bike strip-and-rebuild, or when I bleed them while changing the pads (always the Marshy method; Shimano sintered pads). No TLC other than squeezing the levers once or twice a week if not being used (lockdowns) to flex the seals and move the pistons. If anything they work better now than when I bought them.

if the metal that is normally sealed up is wet, then its possibly the port as the port is in the middle, but if its dry, then fluid is coming from elsewhere and that could be the pistons.

Cool. Would be interested to know.

Wow, I’m surprised this is still a problem. I’ve been off the bikes for a couple of years due to a bad back but getting back into it now, my old M615s that replaced my other leaking calipers are fine after all this time, I think it might be something to do with the pistons being a different material. My Hope’s are just brilliant (when correctly bled and lubed) I’d happily have them on all my bikes but cost is a factor at the moment.

Also, not been on here for ages, I’d forgotten just how awful this site is to use with all the pop-ups and ads taking over the page!

@montgomery

No TLC other than squeezing the levers once or twice a week if not being used (lockdowns) to flex the seals and move the pistons

I think this bit would be saving your brakes.

I believe the issue is oil leaking past dry seals. My daily ride (commuter) has never suffered from squeak Shimano brakes, whereas my other bikes (used once a week max) have always got this issue eventually.

i’ve had two slx m675 calipers and a zee m640 lever leak. i’ve concluded that life is too short to be arsing around with shimano brakes. bought a pair of hope tech 3 e4. perhaps the best upgrade i’ve made in 28 years of riding.

I’ve had no issues with calipers leaking on a set of XT8120 4 pots – 2 years and 2000 miles covered so far. But a seal did fail in one of the levers – I bought a cheapo deore lever and swapped the lever blade off the old XT lever – works well.

The only place I’ve ever read about leaking Shimano Calipers is here.

None of mine, and none of anyone I ride with have ever had any issues with Shimano.

I’d go as far as saying that in ‘real life’ TM they are still seen as being flawlessly reliable.

Are road callipers also affected?

Yep, i had a warranty replacement 105 calliper, when that failed i gave up and bought Hope RX4s – no leaks and enough power to stop a freight train.

@snotrag I’ve got a bag full of failed shimano levers and callipers 🤦‍♂️

I selected the words “leaking Shimano Calipers” from snotrag’s post, right-clicked and selected Search..
Yep, only ever mentioned on STW
I guess if you actively avoid the information, you wont see it anywhere else 😆

I’ve got 3 bikes with non-leaky calipers, ranging from about 2014. But I’ve also had some that leaked from new. It’s a thing.

My experience is the same as Lardman’s above – I don’t recall this happening on a bike I rode frequently, it’s been on less ridden bikes that have sat there for times. Maintenance squeezing of the levers sounds like a good idea.