Master cyl. problem (help)

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Nov 12, 2010 | 04:43 PM

brihvac

Thread Starter

Road Warrior

Joined: Jul 2007

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From: Delaware

Master cyl. problem (help)

I got an aftermarket front master cyl when I changed my bars. I installed everything and bled with my MightyVac. Took a long time but I finally got it. Brake was nice and solid. While working further on the bike I had to pull the master cyl off the bars. I did not open it, I just pulled them off the bars and laid it aside (maybe upside down) Then put it back on when I was done
ISSUE:
I pulled the front wheel and put another on. I then went to pump the front brake and nothing. Soft as can be and nothing. I put the MightyVac on and it will not pull any fluid out of the master cyl. I pulled the line off the master cyl and sqeesed the brake and nothing will come out of the master cyl. What happened? I do not know what direction to go here. Any advice on what I can do?

Nov 12, 2010 | 05:12 PM

dawg

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Joined: Jun 2006

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From: Vermont

Didja check that little tiny hole in the bottom of the M/C to see that it isn't plugged?

Nov 12, 2010 | 05:31 PM

1931jamesw

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Maybe somethings going on with he plunger inside there,

Nov 12, 2010 | 05:53 PM

brihvac

Thread Starter

Road Warrior

Joined: Jul 2007

Posts: 1,462

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From: Delaware

The hole is clear. The master cyl is brand new. I have not even rode the bike since I put it on. The only thing I did was accidently pull the brake while there was no wheel on the bike. I don't see how that would be an issue.

Nov 12, 2010 | 05:56 PM

1931jamesw

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maybe the the pitons in the caliper are all the way squeezed. see if you can press them back into the caliper.

Nov 12, 2010 | 05:57 PM

dawg

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From: Vermont

Quote:

Originally Posted by brihvac

The only thing I did was accidentally pull the brake while there was no wheel on the bike.

How far out did the pistons close with no rotor in between them? How did you get the pistons to close back in?

Nov 12, 2010 | 07:05 PM

dope_man_21

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From: Carrollton, Georgia

I have never done it, but I have been told that you can pull in the brake lever and tie it off (with the master cylinder level) and leave it over night and if there's any air trapped inside it will rise to the top, thus giving you a bled master cylinder/brake system.

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Nov 12, 2010 | 07:39 PM

brihvac

Thread Starter

Road Warrior

Joined: Jul 2007

Posts: 1,462

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From: Delaware

Quote:

Originally Posted by dawg

How far out did the pistons close with no rotor in between them? How did you get the pistons to close back in?

To be honest with you, I dont even think they moved because I didnt have to push them back when I put the wheel back on.
I went and fooled with it some more. I hooked the MightyVac up and opened the bleeder. The fluid just sat in the tube not moving. BUT, when I pulled the brake in and out I could see the fluid moving back and forth in the tube. I had 25hg of vaccum but the fluid just kept going back and forth as I pulled the brake in and out.

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