Master Cylinder Explanation

[clutch]

OK, so it's easy to see why my caliper didn't want to release the disc, there's a lot of crud in there. Waiting for my rebuild kit from DCC but just want to make sure I've done everything I need to do before reassembly. In the second pic, the port on the right I'm guessing is a return? It looks like a blind hole to me, how small is the pathway? I just can't figure out if it is blocked or not.

 

[killian101]

blow some compressed air into those holes. If its blocked, the air will unblock it.

 

[clutch]

blow some compressed air into those holes. If its blocked, the air will unblock it.

Tried a compressor and blow tip...seems like nothing passes thru. Only one of the holes exits into the cylinder. Scratching my head...

 

[Redbird]

As I recall, there should only be one port in operation. There is no return.

 

[crazypj]

Both holes operate.
The left side on should be about 0.015" dia.
You need a single strand from a cable or wire brush to poke at it
The primary seal puts the pressure, the secondary seal is open to the 'big' hole and will move fluid about when your bleeding brakes. If you have excessive travel (primary seal failure) secondary should move far enough to give some brake pressure when it covers the leak hole

 

[Redbird]

I stand corrected.
PJ, is that a normal setup?
I haven't rebuilt a motorcycle M/C yet, but I've rebuilt a few automotive M/C's and have not seen two ports on the same line.

 

[crazypj]

Don't think I've ever seen a motorcycle that didn't have two holes and primary/secondary seals

 

[clutch]

Both holes operate.
The left side on should be about 0.015" dia.
You need a single strand from a cable or wire brush to poke at it
The primary seal puts the pressure, the secondary seal is open to the 'big' hole and will move fluid about when your bleeding brakes. If you have excessive travel (primary seal failure) secondary should move far enough to give some brake pressure when it covers the leak hole

Thanks CRAZYPJ. That's exactly what I was looking for. That would be small enough to not be seen by the naked eye if it is clogged up. So, does that hole go thru like the other hole (meaning, are there 2 holes in the chamber too)?

 

[ktree]

OK, so it's easy to see why my caliper didn't want to release the disc, there's a lot of crud in there.

what does the caliper look like? I hope you've taken that apart as well. Might as well clean it out and replace the seal for 5$ while you're at it. Usually the old pistons are all rusted and the seals are petrified. Get a braided stainless brake line for 25$ too. Somewhere I heard the old rubber ones were meant to be replaced every few years (and seldom were). I'm at this point with any "new' bike I get - if one component of the brake system is nasty, they all are

 

[crazypj]

Brake lines should be changed every 4 years ;D
I'm as guilty as anyone though, I've ridden my 360's with original lines (shows just how well they are made in my opinion )
None of them are cracking but I have replaced the 'finished' one with braided SS and I'll do the others as and when I get to them

 

[clutch]

Caliper was apart (simply because it was the easier thing to try first). Piston moved freely. Pads were hanging up but just needed to get the scale and crud out of there and then they functioned perfectly. I'm waiting for my rebuild kit from DCC so hopefully I can get this together and on the road soon.