Front brake piston stuck

http://imgur.com/3vWKSMQ

I got a rebuild kit for my caliper but when I got to putting the piston back in it got stuck. I've tried pushing it with my hands, a screwdriver handle and a socket. I got nowhere. It's maybe a third of the way in there. There was a light coating of grease on there to help it slide in. Any tips?

 

Hey austinjg, welcome to XJBikes! This topic is one of my favorites - not only because I have been there, done that, but also its one of the funniest problems to resolve. There are a ton of existing threads about how to fix it, from the craziest to the professional. If you do a search you'll find some, but wait a day and you will have replies right here too!

NOTE: a stuck front brake is no laughing matter - it can be the end of the ride. Stories of removal are where the laughs are

 

Take it back apart and see if the seal is damaged. A little compressed air will help pop it out.
while it is all apart and no seals in place slide the piston in. It should slide in easily, if it does not then you have more cleaning to do. After that lightly coat the seal with brake fluid and install in the grove. Lightly coat the piston and slide it in, it helps to twist the piston while pushing it in. It should go in fairly easy with light pressure

 

Check the groves in the caliper bore for any debris, if so clean it up gently with a dental type pick.

 

Safest way is to press it back out via a grease gun

 

you can also clean the grooves with small brass wheel brushes I get them from chacal

if thats just a dirty piston you should clean it better .if it is pitted like that on the part of the piston we can not see and will be in the path of your new seals you will need a new piston.
ouch costly part

 

It's only pitted like that where you can see it. Is that too bad to keep using?

 

when you get the piston out measure where the pits stop and how deep down the seals are the piston does extend above the face of the caliper so you have a little wiggle room , if it extends down into the seals you will cut up the seals and end up leaking fluid. you would definitly want to plan on new piston if this is the case with new seals.
thats a 550 caliper. I will measure my exposed part of the piston to help you out. Check your inbox I started a conversation with you the day.

you can keep using it mew are about 90 bucks iirc.

 

Did you get the piston out? No one recommended compressed air yet, the fun method.

When mine was stuck I just used my brake to remove it: pulled the caliper, removed the pads, reattached the brake line and kept pumping the lever until the piston gave up its grip. Not as fast as grease or compressed air, but less mess and danger.

 

I did this the other day grabbed the inside of the piston with my thumb to hold the progress as piston. squeeze and hold lever for a few seconds, moved out about .2 mm at a time. had to fill mc but it came out after 20 minutes.
it is when you remove MC first you have to go grease gun or air. unless pumping failed

 

I did get it out! Ended up using a grease gun. Worked great

 

Awesome method. It's also how I found that the engine mounting bolt fits where the bleeder goes (same thread). No hardware open at 12:30 AM

 

gas tank mount bolt works too.

 

That's how I have done it. In my case, compressed air was not enoug so I took a 10mm bolt, drilled a 1/8" hole down through the center and tapped the head end to receive a zerk fitting.
Worked like a charm!

 

I just use a bolt to plug the banjo bolt port, then back the bleeder screw out a couple turns and use it as a zerk, they're basically the same size....much faster and less work too.