I fucking did it again, just a few minutes ago. This time on a bike. I had the old brake pads out, i leaned on the handle bar to stand up and get the new ones because I’m old and managed to bump the brake handle against the wall with my body weight. The caliper piston shot out of there and mineral oil is all over the place, all over the rotor, all over me. So now i need to order a bleed kit for a bike, which I’d need eventually anyway but I’m just annoyed because I made this mistake years ago on a prius.
I was changing a lug stud, they need to be in the 12 o’clock position to come out but I had the car in park and only jacked on one side and the caliper was already hanging by a bungee cord. As I went to put the car in neutral I pushed the brake without thinking and I hear a thunk followed by a metallic rolling noise. I shot the caliper piston across my driveway. So as soon as it happened on my bike I fucking new exactly how I fucked up. Typing this out has calmed me down, lol. I use arch btw.
TLDR: I tried to change brake pads and shot out my caliper piston. Again.
At least you didn’t try to open the bleed valve via the righty-loosey technique my neighbor tried on his near-new N series Elantra the other week. Snapped that sumbitch clean off. Bailing him out of that one was fun.
Bikes are dead easy to bleed; you don’t need any kit. You should be able to reach the bleeder nipple and the lever yourself without outside assistance which is all I’ve ever needed. Unless this is on the rear brake of a 'Busa with a 27 foot long swingarm installed on it or something. Pro tip: Loosely put the cap on the reservoir when you pump it, otherwise the master cylinder (especially for the front) tends to act like one of them ornamental fountains.
Hose that brake fluid off of everything right away because it’ll eat the finish off of just about anything that’s not bare metal. You probably also want to make sure both the piston and its bore are real clean before you put them back together.