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I shall set the scene - SRAM Level rear brake, brake pads worn out.
Not able to push pistons back far enough using tyre lever method to fit new brake pads, so got a piston reset tool.
Use the piston reset tool, fit new pads, feel accomplished.
But then notice brake fluid dripping from reservoir on brake lever.... Arse.
So me resetting the pistons has forced fluid out - have I permanently knackered the reservoir /diaphragm?
Bike is only 2 years old and and this was only the 3rd set of pads. I had fiddled with lever reach/bite point - should I have reset that before trying to push the pistons back (I don't need to do that on my XT brakes)?
No. Unlikely.
Someone will be along in a minute who knows the terminology but the reservoir can weep fluid when you force it back up like that.
It used to happen on my Shimano Xt sometimes when I'd bled them with worn pads then put new in and forced the pistons in.
They always were unaffected.
I will need to do a brake bleed to replace the lost fluid, so I suppose if I can't get a solid lever and/or it pisses fluid everywhere then that will give the answer
Should be fine and likely it is excess fluid if the pistons are now fully retracted but weren't previously.
How does the brake feel? If ok then it most likely is fine.
A bleed won't do it any harm, just make sure you get any air out.
Could just be excess fluid, especially as you are using a tool that possibly retracted the pistons further than when they were last bled, so that extra fluid has overflowed. All brakes are open systems I think, so technically the reservoir is not sealed.
If the brake works, it’s not knackered.
You could just take the reservoir cap off and check the diaphragm isn't knackered and giving you peace of mind that they are ok, sounds like they need a bleed anyway.
Could just be excess fluid, especially as you are using a tool that possibly retracted the pistons further than when they were last bled, so that extra fluid has overflowed. All brakes are open systems I think, so technically the reservoir is not sealed.
If the brake works, it’s not knackered.
the reservoir is sealed by the diaphragm. fluid should not be able to escape at all. either there was excess fluid above the diaphragm or the diaphragm leaked.
Brake still works, but lever feels spongy - which I had put down to the loss of fluid
low fluid does not cause it to be spongy. Air has got in and not just in tbe resovoir but into the master cylinder and / or lines
can you inspect the diaphragm ? I'll bet its split.
a top up offluid and a rebleed might get it working again but if the diaphragm is leaking it will be vulnerable to air entry
the other possibility is master cylinder seals
i would try a rebleed but order a rebuild kit and do a rebuild asap even if a bleed gets it working
You can get spare diaphragms for Shimano levers for this reason - would be surprised if the same isn’t true for SRAM.