Rear Master Cylinder Question

Rear Master Cylinder Question

Postby Ken Gluckman » Sun May 20, 2012 9:27 pm

My rear brakes were binding when I took the bike out from a long period of non-use. There was a lot of gunk around the master cylinder and I hadn't changed the fluid in a long time (I know -- shame on me...). so I decided to rebuild the rear master cylinder and the caliper.

After disassembling the rear master cylinder, I noted that there are two holes in the port that leads to the reservoir, one about an eighth of an inch in diameter and one about a sixteenth. The eight inch one is clear and runs to the main cylinder. The smaller one, however, doesn't seem to be open. I tried probing it with a tiny drill bit, but it is definitely not open to the main cylinder.

Shouldn't both holes go to the main passage? I am thinking the the smaller one is the bleed and, if it is blocked, that would answer why the brakes were getting stuck. But I am hesitant to really force my way through it until I know if it should be open.

So my question is -- should both holes in the port leading to the reservoir be open to the main cylinder?

Thanks for the help.

Ken
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Re: Rear Master Cylinder Question

Postby Rick Pope » Sun May 20, 2012 9:52 pm

Ken,

I believe you are correct in your thinking, but I'm sure the real expeerts will chime in here in the morning.
Rick Pope: ICOA Rally Director.
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Re: Rear Master Cylinder Question

Postby Goss » Mon May 21, 2012 5:34 am

Hello Ken,

The answer is yes, if you look down the bore of the master cylinder you may see the holes. I use a very small piece if wire from my wire brush to push through this hole then spray brake cleaner and compressed air through the hole.

Good luck.

Regards

Goss
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Re: Rear Master Cylinder Question

Postby Ken Gluckman » Mon May 21, 2012 9:13 am

Thanks for the quick responses. I used a piece of wire brush as mentioned and it cleared out.

Ken
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