This is becoming something of a crisis now. My brakes have had this problem since May and I’ve tried everything to fix it and nothing has worked.
I’ve tried cleaning the pads & discs. Heating and sanding the pads then cleaning them. I’ve tried changing the pads several times. Buying new pads and throwing the old ones away. I’ve tried sintered, semi-metallic, kevlar, seeing if it made a difference. Cleaning the discs every time I changed the pads. The result was always the same, brakes were okay for the first ride or two, then gradually back to the usual poor performance. I’ve also had the brakes bled by a mechanic recently.
I can still ride down descents but at half the speed I should be going due to the brakes being poor.
The discs were fairly new at the time and are nowhere near worn out now.
It has ruined the descents this Summer and has cost me a lot of money constantly buying new pads in attempts to fix the problem.
Is there anything else that I’ve not tried that might be able to solve this stubborn problem?

The brakes are Shimano Deore M615.

Are they Shimano?

Edit: Hang-on, I swear it didn’t say this before:

The brakes are Shimano Deore M615

Maybe the leaky piston seals issue? I’ve got the same & leaky levers & leaky calipers from a mix of deore & zee. It’s a bit annoying…

TADTS (eventually) proceed straight to the shops with you credit card out.

Leaky piston seals leading to new pads getting contaminated?

What’s your bike cleaning regime (if you have one)? Bucket and sponge/hose? Any cleaner? How do you lube – what and where?

Can’t be because the brakes are not losing oil, the hydraulics are alright and they’d be getting spungy in no time if they were leaking.
The bike has been sat in the garage for the last month doing nothing and the brake still feels okay in that department.

I forgot to mention the front and rear both have this stubborn problem and it started at exactly the same time. No mechanic has yet to be able to solve it.

It’s ruining rides and costing me money, which I hate throwing money away, because I hate working.

You need new calipers. Unless you’ve been getting oil on the pads some other way, it’s the calipers that have failed.

You won’t notice a change in lever feel initially, especially as you are chucking new pads in there repeatedly. It’s only a very fine mist of oil on each pull, but it’s enough to cause your problems.

A dusty look to the calipers is often a tell tale sign too.

Bike cleaning is via the Mobi Jet Washer V17 – the one sold on chain reaction. It is the same one I’ve always used for over a year before this problem started. It is the same way I clean my other bike (which has also got hydraulic disc brakes) which doesn’t have this problem.

I don’t spray any oils on the bike. Chain is oiled by wet lube.

I had problems with a batch of uberbikes pads I got. Bought a good few sets in one go. They would work fine a wee while then lose all power and howl like a banshee. Tried sanding, cleaning discs etc. Eventually got some other pads and so far so good. Maybe an isolated batch, but was a complete pain in the arse until I figured it out.

The brake pads I’ve been trying since this problem started have come from all over the place (Uberbike included).

Regarding the calipers. Is it common for both brake calipers to fail at exactly the same time?

I might consider buying one new caliper & new set of pads- just to see if it fixes the problem – if it does then I’ll get the other one.

As others have said, it’s the calipers leaking very small amounts of fluid into the pads. I’ve had this with several (5) sets of Shimano brakes.

I think if you use the bike regularly, it seems to be okay, but limited use seems to exacerbate the failure…I have no idea why.

You can recover your rotors with a combination of oven heating to 160c and then cleaning with a scouring pad and isopropanol. The pads can be recovered using hot water, scrubbing and Fairy liquid, but it won’t last, once the seals have gone…it’ll need constant fettling.

I have Hope on all the MTBs now. Still have Shimano Hydros on the road and cross bikes, but the front on the road bike is starting to howl, especially when wet.

The calipers were 1 year old when this problem started and had done 2,500 miles.

It is very poor if both calipers have failed at the same time after such little use.

Does “irregular use” count as using it about twice a week ? That’s about the use it was getting until the last month where I’ve got so sick of it, it’s just sat in the garage while I ride the other bike.

I had pretty much the same problem with those brakes, though only with the back one. Changed the caliper and it sorted it out.

Did you get the problem after such a short time as me (1 year) ?

Is the leak so slight that even after many months, the brakes still don’t feel like they need bleeding ?

They only leak under pressure. A leak will not lead to needed a bleed as it doesn’t suck air in and any loss of fluid is made up by fluid from the reservoir – thats what its there for. We are talking tiny tiny amounts of fluid.

Mine all failed within a year. Mine were used less than once per week.

Several sets of shimano done the same here

Now on hopes or mechanicals on all bikes.

Wouldn’t piss on a shimao brake these days

I had this with some XT brakes. They were replaced under warranty. The new ones have been fine so far.

i recently had the same problem with my rear m615 brake, sent it off for w warranty claim, shimano sent a new complete brake back, but i was told its usually down to the caliper seals having a very slight leak, and to be honest if it happens again ,i would rather just buy a new caliper than have to wait four weeks for a replacement from shimano, the seals seem to be very prone to developing a leak due to the seals drying out abit if not used on a regular basis, if shimano took its head out of its own arse, and sold seal kits, we wouldnt have this problem of warranty claims, you could then buy a new seal kit and fit it yourself , bloody shimano lol.

OP, You can deny it as a possibility however there are numerous threads regularly occurring (at least weekly, do a search) with the same symptoms solved in the same way.

Did you get the problem after such a short time as me (1 year) ?
Is the leak so slight that even after many months, the brakes still don’t feel like they need bleeding ?

Was about 2 years I’d had them. I only waited a few weeks after the problem started to change the caliper. Bleeding didn’t work, cleaning didn’t work, changing the pads didn’t work, so had to be the brake system itself and changing just the caliper was a cheap (~£25) way of testing this. Very easy to change over too!

i recently had the same problem with my rear m615 brake, sent it off for w warranty claim, shimano sent a new complete brake back, but i was told its usually down to the caliper seals having a very slight leak, and to be honest if it happens again ,i would rather just buy a new caliper than have to wait four weeks for a replacement from shimano, the seals seem to be very prone to developing a leak due to the seals drying out abit if not used on a regular basis

Unbelievable having to wait 4 weeks, who can wait that long, looks like if it is the Caliper I’m going to have to get a spare in stock so that when my next one fails there is immediately a replacement when the old one is set off to Shimano.

Apparently the warranty is valid for 2 years ?

You can recover your rotors with a combination of oven heating to 160c and then cleaning with a scouring pad and isopropanol. The pads can be recovered using hot water, scrubbing and Fairy liquid, but it won’t last, once the seals have gone…it’ll need constant fettling.

I didn’t realise the discs needed all this to de-contaminate them. How do you oven heat them without contaminating the oven ?

You’ve been told the answer. If you don’t want to believe it, that’s up to you.

Why, after excluding all other possibilities you choose to ignore it is a mystery to me!

Any advice on how to oven cook the discs without contaminating the oven ?

I’m fairly sure I just cleaned my disks with IPA or nail varnish remover last time I contaminated them. Worked fine.

Would just scrubbing the discs with this work:

https://apcpure.com/product/Isopropanol_99_9_ACS?track=1&gclid=CjwKEAiAjIbBBRCitNvJ1o257WESJADpoUt0IJcIWUVQJY3uXxVZ7RizLt5aURCXqzzxtLNSXrkLtBoCYfrw_wcB

Yes.

Not sure why others are baking the disks.

Any advice on how to oven cook the discs without contaminating the oven ?

You don’t cook them, resurface\scour them using wet and dry and hot soapy water (washing up liquid), then bed them in again. Chemical cleaners are crap and don’t remove baked on dirt.

Scour them with water heated to 100C by Kettle? Then rub them with wet & dry ? That should be easy enough to do if thats what you mean

The reason for baking is that fluids are partially absorbed into the surface pores of the rotor when the rotor is hot, so, clean when it’s hot, not when it’s not.

Yes its easy, use hot water and washing up liquid on the disks instead of brake cleaner, pads are best heated until they stop smoking snd then resurfaced with wet and dry.

http://www.pinkbike.com/news/Tech-Tuesday-Silence-That-Squeaky-Disc-Brake-2011.html

Okay thanks for the info

New Brake Caliper is on order (£25 for the Deores). Then I’m going to clean the disc and pads using the advice above. For the rear brake only. Because that is the worst performer at the moment.

If this solves the problem, then I’ll do the same on the front.

Has anyone seen Shimano address this issue yet?

My dad’s brakes are suffering exactly the same, the common factor seems to be

– Shimano Deore
– Used intermittently
– Stored in an unheated space? (hung in the garage).

I keep eyeing up road bikes with discs but the ones I like are typically specced with Shimano hydraulics, would be good to know if it was a batch issue, a model issue, etc etc

Shimano Deore
– Used intermittently
– Stored in an unheated space? (hung in the garage).

That ticks all the boxes for mine.
Shimano Deore
used about twice a week on average, but sometimes only once a week
Stored in a shed

Constantly Contaminated in about a years use.

I’ve got the same problem but mine definitely need a bleed too. Might just get a new calliper first.

shimano brakes seem to come up on here and other forums alot lately for the same problem of leaking caliper seals, may be if more people sent emails complaining about the poor quality of their seals, hopefully one day they might take their heads out of their backsides, and decide to sell seal kits. i wont hold my breath though knowing shimano, or maybe they would listen more when lots more peolpe change from shimano brakes to using other makes.

Might be worth reviewing your bedding-in process. I’ve found Deores to be quite particular in their bedding in requirements.

Basically, I had the same problem and was being too aggressive too soon when going through the prescribed Shimano process.

My first ride with those brakes was the Borrowdale Bash followed by another 16k near Skiddaw – hardly what I call following the ‘bedding in’ procedure! Maybe thats why they didn’t last longer than a year

I had the same with a set of deore brakes. Binned them in the end (kept the levers). Rescued the discs with fenwicks disc brake cleaner