SLX brakes

[paxterg]

My SLX brakes were squealing and down on power, I replaced the rotor and pads. They were great for 3 outings, quiet and powerful braking. Unfortunately this evening they are back to squealing and spongy. Could the pistons be leaking brake fluid? Exasperated here, cleaned the pads and rotor with Holts disc brake spray but no good at all!

 

[fossyant]

Could be - but also may need bleeding if you've not done them before. They are a doddle.

Have a good look round the caliper to see if it's leaking.

 

[paxterg]

Just recently bled, surely that wouldn't influence the squealing? There is no obvious leak but there definitely is some gunk around the caliper.

 

[Ming the Merciless]

Squealing is usually contamination. Remove pads and sand them to remove top layer. Clean up calliper. Give rotors a clean as well with isopropyl alcohol. Put a brake bleed block between calliper pistons. Squeeze brake lever hard. See if the bleed block gets any brake fluid on it. Check the bleed nipple is done up tight.

 

[I like Skol]

Once had an XT caliper start leaking. It was so slight you couldn't really see it, but the pads kept getting glazed, losing bite and squealing lots. Went through a couple of pairs of pads before I discovered the cause and replaced the caliper, problem solved. Caliper never looked damp, it was just slightly darker than the other good one!

 

[fossyant]

Once had an XT caliper start leaking. It was so slight you couldn't really see it, but the pads kept getting glazed, losing bite and squealing lots. Went through a couple of pairs of pads before I discovered the cause and replaced the caliper, problem solved. Caliper never looked damp, it was just slightly darker than the other good one!

It's a Shimano thing.... MrsF's SLX would not work well due to storage - traced it down to the bleed point not being mega tight - slight leak.

Pads need binning if contaminated, disks, just a good scrub.

 

[fossyant]

Should be no gunk around the pads/calliper...

Love hydraulic brakes on MTB's - amazing. Usually fuss free. If they are't - user error or a failure.

 

[Gunk]

Try cleaning pads and discs with fine wire wool and brake cleaner, usually solves the squealing