Braking Piston Stuck, gy6 disc brakes

[BuggyLegend]

The origins of this thread started with another story but I thought it may be helpful if, since I encountered this issue while dealing with a different issue, I posted a separate thread for someone dealing more specifically with this issue. Long story short one of the pistons in my master is stuck which is stopping my front brakes from working at all and I have no idea where to start to clean it. I bought my buggy used and i think someone adjusted the bolts/rods that push in the cylinders to where on the piston that does work can still get pushed in, which operates the rear disc brake. So can someone walk me through how to disassemble the reservoir and such to where I can clean it, and how to unjam the cylinder? Please and thank you so much!

[bear]

There are a couple of different cylinders out there so how bout some pics?

[BuggyLegend]

Of course!

[BuggyLegend]

Let me know if you need any other specific pics. I will get them when I get home

[x-bird]

Starters.
drain pan underneath
Remove brake lines.
Remove pin holding the Rod linkage block.
Unbolt master from the frame.
drain reservoir.

Where the rods go in should be a snap ring in a groove. Using snap ring pliers, remove the rings.

To get the pistons out, cover put a piece of cloth on your work bench (or a piece of lumber) and begin somewhat forcefully smacking the master onto the cloth flat on the opening side. once they unstick, they should come out without too much difficulty.

inspect inside the bores for rust or debris rings. if you see anything like that, use a scotchbrite pad and some type of solvent to clean it out.

If the seals on the pistons look ok, (no tears or really chafed edges) they should be able to be reused.

Next to where the seals are on the pistons is a metal portion that is just a bit undersize to the bore. smooth that off with the scotchbrite--if there's any burrs etc on those, sand or file them off.

Use carb cleaner or brake cleaner to flush everything clean, blast it all out with compressed air.

reassemble, fill & bleed.

[BuggyLegend]

OK, I finally got a chance to do all this, that guide was super easy to follow and everything went very smoothly. I cleaned, scrubbed, blew out, and repeated. My only problem now is that whenever I test the pistons out before I put it back on the buggy, when I push them down in they are still pretty reluctant to come back out. I was thinking when I reassembled it that the new fluid would lubricate it some, but if it didn't I didn't want to waste the fluid by having to drain it again and do something else. SO, I was wondering if it was ok to put a little grease on the pistons to help them out?

[rich1]

Originally Posted by BuggyLegend

OK, I finally got a chance to do all this, that guide was super easy to follow and everything went very smoothly. I cleaned, scrubbed, blew out, and repeated. My only problem now is that whenever I test the pistons out before I put it back on the buggy, when I push them down in they are still pretty reluctant to come back out. I was thinking when I reassembled it that the new fluid would lubricate it some, but if it didn't I didn't want to waste the fluid by having to drain it again and do something else. SO, I was wondering if it was ok to put a little grease on the pistons to help them out?

Do not put grease on any rubber brake parts , it will swell them up and ruin them !

[rich1]

Originally Posted by x-bird

Starters.
drain pan underneath
Remove brake lines.
Remove pin holding the Rod linkage block.
Unbolt master from the frame.
drain reservoir.

Where the rods go in should be a snap ring in a groove. Using snap ring pliers, remove the rings.

To get the pistons out, cover put a piece of cloth on your work bench (or a piece of lumber) and begin somewhat forcefully smacking the master onto the cloth flat on the opening side. once they unstick, they should come out without too much difficulty.

inspect inside the bores for rust or debris rings. if you see anything like that, use a scotchbrite pad and some type of solvent to clean it out.

If the seals on the pistons look ok, (no tears or really chafed edges) they should be able to be reused.

Next to where the seals are on the pistons is a metal portion that is just a bit undersize to the bore. smooth that off with the scotchbrite--if there's any burrs etc on those, sand or file them off.

Use carb cleaner or brake cleaner to flush everything clean, blast it all out with compressed air.

reassemble, fill & bleed.

Buggylegend ...go back and check off the list above !

[BuggyLegend]

Thanks for the reply. I was thinking that the petrol in the grease would be bad for the seals. And yes I have thoroughly inspected and cleaned the parts. Do you think the springs have lost some power since one was partially compressed for so long? If so how should I go about replacing them

[x-bird]

there's a slight chance of the spring having done that, very slight. you could carefully stretch it out so it's about 1/4 inch longer. Pretty sure if you search the internet, you'll find plenty of rebuild kits for 1/2 inch (13mm) diameter master cylinders. they usually consist of springs, seals and a snap ring for about $10.00 If you didn't do it, a very light (500 grit at the minimum) sandpaper "hone" job done by hand on the inside of the master and caliper bores should get everything freed up. make sure to flush it clean.

[BuggyLegend]

Ok I will do that and let you guys know. I've been super busy with other stuff lately n its been tornado alley around here but thanks again!

[BuggyLegend]

ok, so today I cleaned up the master REALLY good today and my cylinders are going in and out very well, I slapped on the pin rings, screwed it back on to the buggy and filled the reservoir. So now time to bleed the brakes, right? Didn't really know what I was doing, but from what I read its pretty simple. open bleed screw, press brake pedal, close bleed screw, release pedal. Repeat, Open, push, close, release, open, push, close, release. I know not to release while its open, But I wasn't sure how long to do this, process. The obvious is "until the air stops coming out." So I started out on the rear brake since I KNEW they worked before I started any of this. I opened the screw, pressed (fluid came out with a bubble or two) closed screw and released the pedal. And repeated a few times. First I didn't know how much to take the screw out, also after a few times somtimes the fluid would shoot out, some time just a little bit with some fizzy bubble. sometimes no noticeable air. I did notice that there was a little suction noise when I would open the screw again. Really need some help with this procedure. On the other hand, When I tried one of the front brakes (which didn't work to begin with because the piston was stuck) and when the screw was open the the pedal pressed there was no fluid coming out at all, I tried it a few times and nothing, I pulled the screw all the way out and it was pretty nasty looking. So instead of wasting time I moved to the back. -_- this is starting to become more and more of a failed project. Thanks for all the help guys!

[zman007007]

sounds as though your brake line may be clogged up or crimped. take lines loose from both ends and see if you can blow air through them

[x-bird]

Originally Posted by BuggyLegend

I pulled the screw all the way out and it was pretty nasty looking. So instead of wasting time I moved to the back. -_- this is starting to become more and more of a failed project. Thanks for all the help guys!

The typical car method you describe isn't very effective--if at all, master's piston stroke is too small, air leaks around the bleeder screws very easily etc.

these brake systems are like this for everyone.--or at least those that try to take care of them.

Given the gunk, here's what to do --flush the system. No if ands or buts. disconnect the lines, buy some brake-kleen and use the little tube to blast the lines til they run clean. blast out with compressed air and let dry. do the same with the calipers by blasting through the line port with the bleed screw removed. You know what you did with the master? you may NEED to do that with the calipers. Whee, fun ain't it?
put it all back together dry.

Find a local agro-coop , agway, feed store etc. buy a couple $1.20 livestock syringes. get some clear hose with about 1/8th or 3/16ths id if you don't have it. some plastic nipples that fit tightly into the hose and the bleeder screw opening.

fill the syringe and pump fluid in from the furthest caliper until the reservoir begins to fill. suck off any excess with another syringe. repeat until no more air bubbles come up in the reservoir. move on to the next furthest caliper and repeat. same til all 4 are done.

[BuggyLegend]

Ok, I will try that when I get a chance. But here's some other new discoveries I've made since. I took the line's off and blew air through them, they were ok. So I checked out the caliper. Took the bleed screw off and blasted them out with cleaner and then air, seemed fine. So I started back to the master. It appeared as though the piston that pushed fluid to the front 2 calipers was not doing what it was supposed to. I took the master off and with fluid still in the reservoir when I pushed in the right piston (operates rear brake) fluid leaked out. When I pushed in left (operates front 2 brakes) nothing came out. Should I just get a new master? Also do I HAVE to put a hose connected to some sort of reservoir filled with brake fluid on the bleeder screw when I bleed the brakes? Thanks again guys!

[bear]

Just an "fyi" you might be able to get a loner brake bleed kit from your local auto parts store, they are a real time saver on these projects!

[BuggyLegend]

Ok guys, I know its been a long time since I've been here, and frankly I'd hoped I wouldn't have to... I bought I brand new Master Cylinder. I put it on, connect the lines and try to bleed the lines AGAIN and its just not working. I am going to go get some brake (line) cleaner tomorrow and give that a good rinsing and try again I suppose. On a different note, when I push the pedal in and out fluid is coming out around the cylinders, fml. I don't even know what to say about that. I mean, it's brand new. Please help, thanks.