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Rear brake problem

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Turns out I took too much slack out of my rear brake pedal.... Was fine in the trails but when we got out onto some pavement, after a couple minutes my rear brake stuck on and forced me to stop. Got extremely hot. :facepalm: . I was able to pry the pads away from the rotor after it cooled off some to get home. Now, I cannot get the plunger in the caliper to move all the way back in. It will move out fine with when i pump the pedal, but will not go back in. I took the plunger out and inspected it, and the inside of the caliper which all looked fine, then blead the system and its still doing the same thing....any ideas?

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The answer is in the first line of your post.

 

Readjust the brake pedal so you have some slack before it starts pushing the master cylinder piston.  The reason you can't move the piston back is that the bleed hole in the master cylinder piston isn't able to move far enough back to bleed fluid back into the reservoir.  You say you can move the caliper piston out but my guess is that you can't move it very far.  In a properly working system you would be able to jack the piston completely out of the caliper.

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I failed to mention that i did already re-adjust the brake pedal so i have slack. And i can pump the pedal untill it pushes the piston right out of the caliper as well. When i put it all back together, and bleed it, its the same thing, i can pump that piston out all the way but will not go back in....

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Did you fill the reservoir too full?  There is a mark on the reservoir for "full" .  If you fill it to the top there isn't anywhere for the fluid to go when heat causes it to expand.

 

If that isn't the problem I would make sure that the caliper piston and bore are clean.  The exposed portion of the piston gets a bit of crud baked on over time.

 

Maybe others have suggestions.

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Did you fill the reservoir too full?  There is a mark on the reservoir for "full" .  If you fill it to the top there isn't anywhere for the fluid to go when heat causes it to expand.

 

If that isn't the problem I would make sure that the caliper piston and bore are clean.  The exposed portion of the piston gets a bit of crud baked on over time.

 

Maybe others have suggestions.

Thanks for your help. I had the cap off the reservoir the whole time so i could add fluid when needed..Both the piston and bore are clean as well. I am wondering if i am not getting it blead properly....If there was an air pocket in the caliper would that not let the piston retract back into the bore?

Edited by chartersj

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when you say it wont go back in do you mean sitting in the garage looking at it? Will the wheel spin freely or  maybe with a little drag? Or do you mean while out riding and it is locking up on you?

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when you say it wont go back in do you mean sitting in the garage looking at it? Will the wheel spin freely or  maybe with a little drag? Or do you mean while out riding and it is locking up on you?

 

When i had the caliper off the bike and in my hand, I couldnt get the piston to retract. I spent some more time troubleshooting and turns out i still didnt have the pedal adjustment backed off enough  :banghead: . I must of adjusted with worn out brake pads and then when i put new ones in they where way to tight?? which is werid because i put on lots of kms that way before they heated up enough to start dragging on me.

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if you still cant get it to move back in then use a c clamp with it off the bike. Rig it up some way to push it back in. If it was out way far make sure it is aligned and square as they can tilt if out too far and that makes them hang up going back in too. Then adjust the the pedal turnbuckle to get the pedal where you want it as a rough adjust and the pedal height adjustment together at the same time to get it fine tuned.

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