Master Cylinder Non-Rebuildable?

[jswhite]

Hi All,

Bought an 81' 650g and am rebuilding the calipers and cylinders on the brakes and have come to a dead end and don't want to break anything.
Got the master cylinder off and took out the snap ring. The videos I have watches show the piston sliding out at this point. Well the washer, or whatever it is, that is keeping the piston in will not come out even after a few friendly taps with a deep 10mm socket, which fits conveniently over the piston. It doesn't feel like a washer, it feels like part of the body itself, which seems weird.

Here is a pic.

1. Did the GS' come with master cylinders which could not be rebuilt?
If not... I will have to give it a pretty good wrap to get this broken free which might do further damage but will most likely break the washer.
2. A washer didn't come with the rebuild kit, can I use any washer which has the right internal/external diameter?

Any help is appreciated

Thanks!

 

[Agemax]

As you have already bought a rebuild kit then that should suggest to you that they are indeed rebuildable! The piston is just stuck in with dirt and crud. You should have a new piston included in the kit so grab the end of the old one with vice grips, twist and pull at the same time. A good soaking with wd40 or similar will help losen it up.

 

[GSXR7ED]

Definitely soak the MC and then twist out with needle nose vice grips as suggested. The circlip type washer keeps the Piston in-place so your kit should have come with one. Have you looked at the fische breakdown for your year bike?


Ed

 

[Steve]

... will not come out even after a few friendly taps with a deep 10mm socket, which fits conveniently over the piston.

Maybe try a few "not so friendly" taps? :-k

There is nothing special about that washer, other than physical dimensions, so give it a few taps to break it free.

.

 

[Guest]

I had one of those a couple of years ago which appeared to be siezed solid. It took several days of heating/cooling, lubricating, tapping with a hammer, and pulling with pliers. Yours will free up, but you need to be patient, and not damage the bore. If you can support the assembly in a firm, square position you can afford to be a little less friendly with the hammer, as Steve suggested.

 

[jswhite]

I had one of those a couple of years ago which appeared to be siezed solid. It took several days of heating/cooling, lubricating, tapping with a hammer, and pulling with pliers. Yours will free up, but you need to be patient, and not damage the bore. If you can support the assembly in a firm, square position you can afford to be a little less friendly with the hammer, as Steve suggested.

Good call, I will be a little more persuasive.
The weird part about all of this is that the piston inside moves freely and smoothly, it is just that washer, that holds the piston in, which is being stubborn.

I'll try some soaking.
Thanks all.

 

[GSXR7ED]

Here's what popped out of the MC when I rebuilt it:

Is that washer you're talking about...look anything like the cir-clip above? It has two eyelets that require a special tool to squeeze the cir-clip out of the wedge it's in.


Ed

 

[jswhite]

Here's what popped out of the MC when I rebuilt it:

Is that washer you're talking about...look anything like the cir-clip above? It has two eyelets that require a special tool to squeeze the cir-clip out of the wedge it's in.


Ed

Thanks for the pic. No, it looks to be a flat washer which was under the circle clip. I already took that out. I can push the piston down and let it pop up and it gives a clunk noise to this. Makes me wonder how a washer could be that seized when everything else is working fine. That's why I was wondering if it comes as a whole unit rather than being rebuildable.

 

[Nessism]

What I do is grab the plunger with some strong pliers such as needle nose vice grips and then push in the plunger as far as possible and then pull back quickly and shock that washer to get it loose. It may take several tries. Soaking the washer in something like PB Blaster will help break down the crud too.

 

[jswhite]

What I do is grab the plunger with some strong pliers such as needle nose vice grips and then push in the plunger as far as possible and then pull back quickly and shock that washer to get it loose. It may take several tries. Soaking the washer in something like PB Blaster will help break down the crud too.

This worked well. The washer came out then I was able to take out the rubber piece, but the piston remains. I'm letting it be full of WD40 all night upside down and I'm hoping the piston will come out tomorrow. Still think its weird that the piston goes in/out fine but is still stuck cause if I saw right from the diagram, the piston itself should be the only thing in there at this point. Oh well, see what happens tomorrow.

 

[Nessism]

Maybe try some compressed air?

 

[1948man]

This worked well. The washer came out then I was able to take out the rubber piece, but the piston remains. I'm letting it be full of WD40 all night upside down and I'm hoping the piston will come out tomorrow. Still think its weird that the piston goes in/out fine but is still stuck cause if I saw right from the diagram, the piston itself should be the only thing in there at this point. Oh well, see what happens tomorrow.

Maybe the bore is gouged or corroded right where the washer was.

 

[jswhite]

Maybe the bore is gouged or corroded right where the washer was.

Update*** soaked in WD overnight and took some needle nose vice grips on it, and it still goes in/out as it should as a piston, but I couldnt pull it out. I dont want to damage the housing, and at this point I am so far in and the piston is damaged enough from me wrenching on it that I must replace it. I was thinking maybe I could get some sort of puller onto the front of the piston. Almost thinking I should just replace the whole thing with the way its going.

 

[2BRacing]

Update*** soaked in WD overnight and took some needle nose vice grips on it, and it still goes in/out as it should as a piston, but I couldnt pull it out. I dont want to damage the housing, and at this point I am so far in and the piston is damaged enough from me wrenching on it that I must replace it. I was thinking maybe I could get some sort of puller onto the front of the piston. Almost thinking I should just replace the whole thing with the way its going.

The OEM Suzuki master cylinder piston kit comes complete with a new piston, the rubber seals, spring, washer and circlip.

Perhaps you can try pushing the piston in with a thin screwdriver or similar, and then use a small piece of hard wood to clean up the area where the washer was. This should remove corrosion or whatever is causing the piston to stick at that point.

Good luck!

 

[Guest]

Update*** soaked in WD overnight and took some needle nose vice grips on it, and it still goes in/out as it should as a piston, but I couldnt pull it out. I dont want to damage the housing, and at this point I am so far in and the piston is damaged enough from me wrenching on it that I must replace it. I was thinking maybe I could get some sort of puller onto the front of the piston. Almost thinking I should just replace the whole thing with the way its going.

I had the same problem and got the piston out by using vise grips on the rod and then applying force to the vise grips with a bar levered over a block of wood with the MC body held in a vise. It was not a delicate operation, very much brute force. On the plus side, the bore of the MC cleaned right up with a bit of fine scotchbrite cloth wrapped around a stick and some oil. If you can manage to get the washer to break loose I bet your MC body will be fine the same as mine was.


Mark

 

[GRAND ROUGE]

Have you tried to loosen the washer by using a socket...or similar hollow round pipe etc....place in bore against washer....and tap /hit with a hammer. At this point, what do you have to lose?

 

[chuck hahn]

A heating with a heat gun or torch. Get some oil in there and watch as you heat. When the oil starts to bubble its hot enough. Then give it a few smack with the socket trick. Idea is to crack the rust and heat will draw the oil into the cracks and loosen it up. Other than the grove for the circlip there isnt anything that an get hurt so smack away.

 

[jswhite]

IT WORKED!!! I got a little more creative with some of your ideas and drilled a hole in the middle of the piston, drilled a screw in, and took my nail puller and with the cylinder in the vice popped the piston out.

Looks like the rebuild was needed.

Thanks for everyone input, one more item will get checked off tonight! :dancing:

 

[jswhite]

Now for the real question, is this thing OK to re-use or do I need to get a new one?
I do not see any pitting on the inside but in the process of removing the piston I dinged up the inside a bit. No cracks but dings, here are some pics. One looks to be right below where the snap ring would be and the other 4 are from the piston, and some of the hammering which I did.
This one is right below where the snap ring would go.

 

[jswhite]

This one is 1 of 4 from the piston