Having lost all rear braking coming down Jacob’s Ladder yesterday, it turns out one of my pistons is playing up on my old style SLXs.

It’s not that it won’t move out when I press the lever, it’s that it doesn’t stay out to meet the disc, if that makes sense. It won’t pump out.

I took the pads out today and, by holding the other piston, managed to pump it out, give it a clean and lubricate with some silicon spray. I did this a few times but it hasn’t made any difference, the piston still won’t pump out. It almost looks like it’s sitting slightly askew in its hole. Deformed seal maybe?

Anyone got any ideas? Thanks all.

Did you clean out the slot that the seal sits in? Often sticky pistons aren’t caused by the seals or pistons, but by corrosion under the seal pushing it against the piston too hard.

Often with Shimano the best bet is just to buy a cheap caliper- they come with pads too so it works out not much more expensive than a seal kit would for other brands.

I didn’t pop the piston out completely, just as far as I dared and cleaned and lubricated around the piston, pushed it back in and repeated a few times. I thought it was a bit strange that it stopped working all of a sudden, which makes me think it’s maybe not corrosion.

Any of the evening crowd?

Anyone know if the new SLX callipers are compatible with the old style levers?