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Discussion Starter #1
Up until recently, my brake problems have stemmed from excessive travel over a period of time. but now a new problem has surfaced.

Went out yesterday for a quick spin and noticed that my front brakes are "sticking" as a use progressive braking.
Got home and played around with it. I can feel and hear the Master Cylinder piston grab and release against the cylinder as I squeeze the lever. It could be the calipers sticking, but the M/C seems to be the culprit.

Any ideas?
What does a M/C rebuild kit cost?
Anybody have the Part #?

I've considered going with a Kawi ZX brake system. This may be my excuse.
 

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Sport,
I'm not really sure if I understand exactly what is going on and I doubt if anyone can explain what is happening without "being there." Before I spent any bucks on replacement anything I would take the calipers totally apart and just clean them. May as well do a complete fluid replacement too. You can do the entire job in less than an hour and it's much cheaper than buying a new brake system. Also, you might take a look at your pads and maybe even run them over some sand paper to remove any glaze or crud on them.
 

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Sport,

There's a brake light switch on the underside of the master cylinder assembly. If the noise you hear is a fairly sharp click on, click off, then it's just your brake light switch doing what it's supposed to do. You can verify by turning the ignition on and watching the brake light respond.

Tell us more about the on-the-road symptoms. Are they still sticking when you're stopped? When stopped and you push forward on the bars without the brake lever pulled, does the front suspension drop some like it would when you have the brake on? How long does it take to release?

Bern
 

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Discussion Starter #4
Lets see if I can clarify...

First, It's not the brake light switch.

Second, Before my road trip I compressed all the caliper pucks and inspected my brake linings. This is a process I do 2 to 3 times a year. The calipers are dry clean and move without sticking. Although I have not serviced the fluid in a couple of years.

The symptom:
Whether stopped or on the go whenever I squeeze the brake, the lever will stop/grab (like the M/C piston is snagging on the M/C cylinder), then it will begin moving again as I increase squeeze pressure. It will do this 5+/- times each squeeze. Trying to find an anology to this I could only think of a moving object across an un-lubricated surface. Until its lubricated it will continue to stick/grab.

While moving this causes the pucks to grab the disc and drop the forks a little. It's extremely unerving when making stopps from a moderate to slow speed.

The reason I feel it is the M/C is because each time I move the lever beyond the "grab" point I hear, for a lack of a better term, the sound from the M/C. Almost as if the M/C is scored and grabbing the piston seal.

I guess it could be the caliper, but with four pucks, it's hard to think that all of them are sticking at the exact location.
 

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That is much clearer. You are right that it would take all four pistons to catch at the same time to do what you are saying because even if one hangs the fluid just goes around it and presses on the other pistons. Sure sounds like something is hanging in the MC. I know you have already done this but just to rule out the obvious, could it be something with the lever and not the MC piston? It's easy to take off and check if some kind of crud is in the slot it pivots in.
 

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Sport,

I haven't heard of a master cylinder failing before but it does indeed sound like that may be your problem. I agree with your comment that, given the symptons, it doesn't seem to be in the calipers.

I've never done a master cylinder (you may want to post this topic under a "master cylinder" topic to see if you can get a response from someone who has) but the service manual does describe replacing the piston and seal set - it doesn't sound too difficult.

Please keep us posted,
Bern
 

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Master rebuild is like $20-$30 if I recall. Its really easy to do once you get that dang C-clip out. You NEED C-clip pliers, but they are cheap at auto parts stores. Take it apart slowly and carefully and mind the way it came out, because you'll need to put it back together in the same way. There is a spring in there, but it isn't under a lot of pressure, still, it could jump out at you a little bit..

My master feels a little "rough" on the inside, if I'm gentle squeezing it, but it doesn't stick like that. The rebuild didn't really improve that feel, but like I said, mine isn't actually sticking.
 

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Discussion Starter #8
Thanks guys,

I still have my old Rool away Snap-On Tool box from back when I fixed airplanes. I should still have a whole set of Snap-Ring pliers to pull out the locking clips.

I'm stopping by the dealer to have them reconfigure the ECU. I'll ask about a seal kit.

Because of the re-occurring problems with braking (as evidenced by all the posts), I'm half tempted to just go with a Kawi ZX braking system. Anybody know if a year model 2004 ZX10R M/C would fit on a 2002 ST providing the bar is 7/8"?

Thanks

[ This message was edited by: Sport on 2006-11-29 16:37 ]
 
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