I ride my mountain bike once a week or so and seem to suffer from squealing brakes every month or so, due I think to contamination. I wash my bike with water, sometimes muc off and oil only with non spray lube. Bikes kept in garage and yet still it happens. I’m using genuine shimano xt sintered pads in shimano brakes. My cx bike that’s got cable discs doesn’t seem to have any issues being treated in exactly the same way. I’m getting mighty pissed off at £40 a month brake habit…. any thoughts as to how to prolong the pad life?

Leaky caliper seal (is it one or both?)

Well known shimano issue, I find in shitty conditions the squealing soon goes away……

Can happen to both, doesn’t seem to be any issue with leaks seals.

Interesting comment Core not spotted it before

Shimano xt (new type) by any chance?, if so then it’s leaky piston seals – get in touch with where you bought them and ask for replacement

I sprayed my bike last week with the pink muc off soap that’s supposed to be disc safe. My road bike sounds like a fog horn under braking now. I’ve sanded the pads down and will bed in again and see what’s wot. Maybe need to change my pads. 🙁

No, not new ones but if it carries on I’ll be after some more! I guess they are about 3 yrs old, never been bled and work like a dream with new pads for a few weeks! Last rode on Wednesday night, today they are squealing and very little power. Properly pisses me off it does!

As above, it will be a leaking caliper seal.

yep, leaky piston seal. Common issue sadly as SHimano brakes used to be very reliable.

Right, new brakes then! Might as well get a 1×11 group set while I’m at it!

How do leaking caliper seals cause squealing brakes but don’t affect braking power?

Ah, my brakes are also loosing power when they squeak, can it really loose so little that I don’t notice any lever diferance after maybe 5sets of contaminated pads?

Came in to see if it was Shimano. Was not surprised. How old? People seem really weird about not claiming on Shimano warranty for some reason…

Came in to see if it was Shimano. Was not surprised. How old? People seem really weird about not claiming on Shimano warranty for some reason…

About3-4 years old and bought second hand. No way they have a warranty!

I’m still dubious that it’s a leak, surely they’d need a bleed by now if that were the case?

Maybe, just maybe a set of hopes to replace them…..

I’m still dubious that it’s a leak, surely they’d need a bleed by now if that were the case?

I had exactly the same problem on M785 calipers. It was a leak. I had them replaced with M7000 calipers (keeping the XT levers) and the problem was solved. To clean the rotors of all residue, I scrubbed them with cream cleaner (mild abrasive), rinsed with boiling water then into a hot oven for 20 minutes.

Thanks for advice, new M8000 brakes on order.

Soon to be seen – how to shorten a brake hose thread….

I’ve had this on 4 brakes. The timings are remarkably consistent, failing at about 2.5 years, which is reasonable wear and tear territory. Since replacement calipers are so cheap and it’s outside the 2 year warranty, I just replace the calipers as they go.