BR666 Shimano SLX Hydraulic Caliper - repair or replace?

[Custom24]

I think I've broken a seal or something in my brake caliper.
One of the pistons was stuck and while trying to free it, I ended up causing a fluid leak (mineral oil in these). The bike hasn't been used in a while, which is why I think one of the pistons got stuck.
I was trying to use a toothbrush handle to give the piston something to press against, but it wasn't flat enough and now the stuck piston is out but at an angle, and oil leaks from it.
There was a snapping noise, but that may have been the plastic toothbrush handle (or the seal, I'm not sure)

Can the seals be repaired (by me) or is it a case of replacing the caliper? I've not tried taking the caliper apart yet. No harm in doing so now, I guess.

Thanks for advice
Mark

 

[I like Skol]

Sounds like you have over extended the piston. This isn't necessarily a reason to scrap the caliper. Clean everything up and carefully push the piston back in straight. You will then need to bleed the brakes, but you would have to do this anyway if you were to replace the caliper. If you do have a stuck piston it is likely to be the one that is still in the caliper, the one that has popped out is moving ok.

 

[Custom24]

Thanks. I tried to push the piston back, but it doesn't budge. It is definitely the skew one that was sticking, because the other one was moving freely before I meddled with it.
I don't know what kind of seal/diaphragm is behind the pistons - is it replaceable, is it something that can be broken/leak?
Shimano techdocs is no help - it just shows the caliper as a single component and doesn't explode it.

I will give pushing the piston back another go.

Mark

 

[lpretro1]

No service kits available for shimano brakes

 

[I like Skol]

Did you ever get this sorted @Custom24

 

[Custom24]

Did you ever get this sorted @Custom24

Thanks for asking!

No, I've managed to get the piston back in square, although it won't go all the way home. When I try to push the piston back further, there is a scraping/grinding noise (maybe the piston is cracked, but I can't see anything. This would tie in with the cracking noise I heard in the first place). When I squeeze the brake lever, fluid is bubbling out of the piston (I think from the sides of it).

I think it's foobar, but I'd like to understand why. What's behind the piston movement - is there a ring type rubber seal, or is it something else?

How can I clean a stuck piston in the future?

 

[mrbikerboy73]

It's only a guess but if the calipers are anything like car or motorcycle brake calipers (smaller scale of course) then there are two rubber seals. The one you can see would be a dust/dirt seal to keep crud off the piston, and there will be another behind that which you can't see. This will be the fluid seal and indeed, a rubber ring type that sits in a recess.
If the piston was pumped out too far, the fluid seal may have been dislodged when pushing the piston back into the caliper, creating a leak. I hope this helps...

 

[mrbikerboy73]

No service kits available for shimano brakes

If this is the case, then it may be time for a new caliper. From my experience of car brake calipers, a new one is far easier and often only a small amount more money than buying seal and piston kits.