Working on brakes.....piston seized??

[Splexin]

I'm stumped. I bought a new M/C, SS lines, and new brake pads for the front disc brake on my 80 Special II. Previous to this, brakes worked fine.

I installed everything but noticed the pads rub the rotor a little much....anyway I can not for the life of me get any brake movement. I took the caliber apart and couldn't get the piston out. Any ideas??? I've literally spent 8 hours working on my brakes today, mostly trying to get the pads in correctly until this happened.

Is the piston seized and am I doomed to buy a new caliber? I just don't understand how it was working and now it's not I bled the system also...

 

[Royboy]

Numerous posts regarding caliper service under the topics heading. New pads sent the piston to unfamiliar territory and it stuck (guess). You'll probably need to rebuild the caliper. Not a big deal and certainly worth doing.

 

[5twins]

A "rebuild" mainly consists of taking it apart and cleaning it thoroughly. If it's not leaking, you probably don't need a rebuild kit. I wouldn't buy one until I had the thing apart and saw for sure that it needed it. Mine has all the original 30+ year old parts in it and works fine - after a good cleaning. It was stuck when I got the bike.

 

[Splexin]

Yeah it's not leaking....but I can tell that it needs to be cleaned. The problem is I can't get the piston out to clean it. Manual says to use compressed air but I don't have access to that. I mean, is there some kind of technique to pull it out?

EDIT: I got it out!!! Bare hands and no injuries or projectiles!

 

[Splexin]

OK so I cleaned the piston and caliber etc....reassembled everything and reinstalled the caliber. This time it felt better, the wheel turns freely and the pads are correct. I bled the brakes fine but I still can't get any brake pressure, pads won't move

Ideas? I don't understand why it's not working....fluid is getting to the caliber just fine but no pressure and no moving pads. I guess that means air is leaking somewhere??? I don't know....

 

[Royboy]

Keep bleeding. If the system is leak tight and the M/C is good the only way you can be without hydraulic pressure at the caliper piston is air (very compressible) in the system.

roy

 

[kvanderploeg]

Bleed at all the banjo bolts as well.

Kent

 

[5twins]

You might try to "back bleed" it. I do this when I get a stubborn one. Many times, air gets trapped right at the 90° fitting where the line connects to the MC. Yes, you can try bleeding it there but it's messy and sometimes you just end up letting more air in. This is easier. Pull the bottom caliper mount bolt and loosen the upper one. Rotate the caliper most of the way off the disc. Using a large screwdriver or a flat bar, lever the pad and piston back into the caliper. This will force fluid up and into the reservoir. Watch the fluid welling up into the reservoir as you pry and if you see any air bubbles, even just a few, you know you've just released some trapped air.

 

[nic81xs]

try burping your master cylinder cap too. sometimes an air bubble can get stuck in there