Front Brake / MC piston Stuck!!!!!!

[kickstart79]

Hello again,

Yesterday I attempted to bleed the front brake of my gs550L. its a 79. I thought I knew what I was doing but it turned out that I didnt. I must have sucked up alot of air in my brake line because the handbrake has no feel to it at all. It is just limp. It has nothing there. I have tried sucking the air out of the brake line but I cant get any fluid to come out. A friend of mine thinks I may have locked the little piston that pushes the brake fluid down the line. I am not sure what he is talking about? Is there a small piston in the M/C? I need help. But i am not going to the bike store down the road they charge 90$ an hour even to look at it. Thats a rip off.

Help me!!!!

[seuadr]

yes, there is a small piston inside there. your piston might be frozen, it probably has not seized in such a short period of time. if you got a manual it tells you how to take it apart, they are all a little different, i would pull it apart, clean it up good, recondition the rubber seals and make sure everything is clean and sticly free, then re-assemble it. if, when you get it apart, it's obviously torn up or worn, i'd get a rebuild kit, the seals can be touchy.

[kickstart79]

Thank you I will attempt to take it apart this weekend. I will see what I come up with. I don't have the Manuel so any help on that would be great.

Thanks for responding so fast.

[Nessism]

You can download the factory repair manual for your bike for FREE from repairmanualclub.com

Get one. Read it. Put it under your pillow at night. Learn. Enjoy!

[kickstart79]

hey guys,
I freed up the stuck piston in the M/C. Now the problem is I cant get any fluid to go through the m/c brake reservoir and down the brake line.?????? Not sure what is wrong here. I cleaned out the m/c brake reservoir and still cant get any brake fluid to flow. the piston is working great tooo. hhhmmmmm any help?

[Nessism]

Put a long piece of clear tubing on the caliper bleeder nipple and suck on the tubing. The vacuum will help draw fluid out of the reservoir and prime the master cylinder.

[kickstart79]

I just tried this there is no luck. There is no fluid coming out of the resiviour at all. I dont understand why it is not coming out. could something be blocking the hole thats the fluid goes down?

[Colin Green]

Have you loosened the brake nipples on the callipers?.. if not the fluid will not flow and the sucky sucky syphon wont work either

[kickstart79]

Do you mean the bleeder nipple? If so I have loosened up the bleeder nipple and tried the clear tube sucking act. And got nothing. I still think there might not be any fluid in the cylinder when I pull on the brake.

[Colin Green]

Do you mean the bleeder nipple? If so I have loosened up the bleeder nipple and tried the clear tube sucking act. And got nothing. I still think there might not be any fluid in the cylinder when I pull on the brake.

Ok.. lets check through a few questions to get a better understanding of what we are dealing with.

1. when you say the lever is "limp" is it correct to assume that you are feeling no resistance? and is the lever returning all the way out under its own violation?

2. Is the wheel on the bike and calipers bolted home?

3. Have the calipers and/or pads been removed during the previous processes?.. it may be helpful to describe the all of the steps you have made during the initial and subsequent brake maintenance.

4. have you tried disconnecting the brake line (at the master cylinder) to see if fluid is working its way through the reservoir holes to the piston and out the other end? If not, you could try working your way through the connections one at a time, reconnecting them behind you... working from the master cylinder to the calipers to see what sections are working. It would pay to empty most of the reservoir contents before disconnection and wrap absorbent wadding (cloth/towel) around the reservoir and bars as best you can to soak up spillage (even cover up the bike with plastic sheeting) to protect paintwork etc from the caustic brake fluid. I am not familiar with your brakes but if they are anything like mine, the reservoir will have a couple of holes (1 smaller than the other) in the bottom of the bowl and opening into the piston cylinder... check to see if they are clear.

Let us know how you get on.. pref with detailed descriptions of previous steps.

Good luck

[Nessism]

Do you mean the bleeder nipple? If so I have loosened up the bleeder nipple and tried the clear tube sucking act. And got nothing. I still think there might not be any fluid in the cylinder when I pull on the brake.

"If at first you don’t suck seed (succeed), suck again until you do suck seed.":-D

Curly Howard (Neal) - Three Stooges

Translated: suck harder.

If you put the master cylinder together properly, sucking on the tube, with the nipple open, will draw fluid down in the piston. It takes a fair bit of suction some times – more than you might think.

Good luck.

[Colin Green]

"If at first you don’t suck seed (succeed), suck again until you do suck seed.":-D

Curly Howard (Neal) - Three Stooges

Translated: suck harder.

If you put the master cylinder together properly, sucking on the tube, with the nipple open, will draw fluid down in the piston. It takes a fair bit of suction some times – more than you might think.

Good luck.

Ahhhh!... Suuuuper Sucky!!

[kickstart79]

Hey guys, Good News I fixed the M/C!!!!
I took the M/C apart three times before I got it to work right. I striped everything down cleaned all the parts with new brake fluid and reasmbeld it back togather. I then used the suck on the clear tube trick from the bleeder again and finaly I got fluid out of it. I am very happy that I did this on my own, with the help of u guys. THank you for all the help.

:-D

[Colin Green]

Hey guys, Good News I fixed the M/C!!!!
I took the M/C apart three times before I got it to work right. I striped everything down cleaned all the parts with new brake fluid and reasmbeld it back togather. I then used the suck on the clear tube trick from the bleeder again and finaly I got fluid out of it. I am very happy that I did this on my own, with the help of u guys. THank you for all the help.

:-D

Well done.. it's a great feeling to be a bit more self sufficient eh! Congrats\\/

[SPARKSS]

I just tried this there is no luck. There is no fluid coming out of the resiviour at all. I dont understand why it is not coming out. could something be blocking the hole thats the fluid goes down?

Inside your master cylinder (M/C) the piston must retract smoothly and completely. The hole(s) at the bottom of the resevoir must be clear and through in order to allow fluid to both refill into the resevoir when you let go of the handle and to maintain a full column of fluid ahead of that piston so that it can be pushed down the tube when you pull the handle. The piston retracted position should just uncover the hole in the bottom of the resevoir when retracted and immediately cover it when the handle is pulled......in order to positively displace that fluid into the brake line leading to your wheel.

If the piston doesn't retract enough to uncover the hole and/or the hole is plugged......significant fluid stroke is lost.
If the M/C piston seals are worn out or damaged or installed incorrectly or otherwise won't seal to the bore (bore worn out or overly honed), the fluid will bypass the piston as it's stroked and pressure won't build correctly in the brake line.

A quick test of a M/C is to disconnect the output line.....block the hole with your finger and depress the handle.......a working M/C will spray hard past your attempt to block it. This should allow you to troubleshoot the upper half of your system at least.

Just to add to Colin's good advice.