You wouldn’t be the first to kill a pair of bladders installing brand new masters but let’s hope not! Lots of folks change pads without pushing back the pistons without incident (should be okay if you haven’t ever topped up the system or bled the brake with the pistons extended) but then I’ve sold plenty of replacement MCs working part time in a shop too. So I think best practice is to always open the system before pushing the pistons back.
Leaking can often be a visible symptom. The most common symptom of a damaged bladder is that a lever brake will pressurize if you pump it a bunch of times but no amount of bleeding the brake will keep it from pulling straight to the bar with a single compression.
If your brake was leaking notable amounts of fluid from the MC my bet would be the bladder ruptured.
It would be simple for Shimano to switch to replaceable bladders in all their ServoWave brakes. Just make it so the bladder cap can be threaded out with a Torx/Hex key and sell replacements.
April 19, 2022, 8:18 a.m. - Andrew Major
You wouldn’t be the first to kill a pair of bladders installing brand new masters but let’s hope not! Lots of folks change pads without pushing back the pistons without incident (should be okay if you haven’t ever topped up the system or bled the brake with the pistons extended) but then I’ve sold plenty of replacement MCs working part time in a shop too. So I think best practice is to always open the system before pushing the pistons back. Leaking can often be a visible symptom. The most common symptom of a damaged bladder is that a lever brake will pressurize if you pump it a bunch of times but no amount of bleeding the brake will keep it from pulling straight to the bar with a single compression. If your brake was leaking notable amounts of fluid from the MC my bet would be the bladder ruptured. It would be simple for Shimano to switch to replaceable bladders in all their ServoWave brakes. Just make it so the bladder cap can be threaded out with a Torx/Hex key and sell replacements.