Front master cylinder 82 GS650G Model Z tricks?

[Michael]

Hey fellas,

I'm currently attempting to rebuild the front master cylinder, I'm using P/N: 59600-49811 to swap out the piston.

Here's the issue... it wont budge! I've pulled the dust seal and removed the snap-ring but the piston will not move past where the snap-ring was seated. It looks to me that the washer has melded with the bore and wont give.

I've soaked it for 3 days in WD-40 to no avail and now I'm ready for ritual sacrifice if necessary.

What are your thoughts, tips, tricks, Voodoo spells for getting it out or is there simply a button I need to push?

Thanks in advance!

Michael

P.S.:Will post Pics in a minute or two.

 

[bwringer]

If you can push the piston further in and then use emery cloth or fine wet/dry sandpaper wrapped around a dowel to clean up the bore, you might be able to do enough good to get it out of there. It will be rather awkward. Maybe wrap a dowel loosely with wet/dry, leave the nose of the dowel clear, then push and turn.

And sometimes you just have to post in "parts wanted" or hit up fleaBay for a rebuildable MC with less corrosion.

 

[hillsy]

The groove where the circlip is located is more than likely burred up and preventing the piston from moving out. You might be able to push the piston in and get some emery paper onto the grooved area to smooth this out but it might just be fubar'd.

 

[hillsy]

Beaten to the punch.

 

[Michael]

My computer seems to think that I can only post one picture at a time

 

[Michael]

Next Image!

 

[Michael]

Next Image!

 

[Michael]

You folks are quick!

I'll give the sand paper a go tomorrow, hopefully it's salvageable since I've already got the kit.

 

[hillsy]

Another thing you could try is compressed air in the banjo bolt hole with your thumb over the holes inside the reservoir. Wrap the MC up in a shop rag so the piston doesn't fly across the room.

 

[mustangflyr]

I had one that was stuck like that and the what I had to do was to drill a hole in the master cyl at the opposite end of the bore to drive out the piston assy. Once all cleaned up I tapped it 1/8 pipe thread and put a allen head brass plug to seal it. Now no sweat if it happens again.

 

[Wingsconsin]

​Might be easier to work on if you removed it from the bike...?

 

[Michael]

​Might be easier to work on if you removed it from the bike...?

Yes it would be, however my landlord has a strict no automotive spillage in the parking lot rule and I'm worried the exposed brake line would drip.

I also am lacking a bench/kitchen table.

 

[Kiwi Canuck]

I have resorted to drilling a small hole into the plunger, installed a self taping screw and used a claw hammer or something similar to slowly pry the piston out, piston is still usable if needed.

The two I had to remove this way were stuck firm and required a fair amount of force to pry out, surprising how hard it was to get them out, but once out easy to clean up the rust and corrosion in the bore with 2000 grit paper & WD40 or similar.

Good Luck

David.

 

[Gorminrider]

Yes it would be, however my landlord has a strict no automotive spillage in the parking lot rule and I'm worried the exposed brake line would drip.

I also am lacking a bench/kitchen table.

You have a problem alright but why not buy some poly sheet and park the bike on it? nail the poly to sticks to give it an edge around, like a swimming pool. Also, rags-newspaper,overalls to soak up. And cover your tank always...Get some old shoes that NEVER cross the threshhold of your apartment building...and nitrile mechanics workgloves to keep your hands clean. These are suprising good nowadays as to feel and grip...

The brakeline won't lose much from the top anyways. The above is overkill for just this, but overall useful for the day you must make a drip or two.

 

[Steve]

My computer seems to think that I can only post one picture at a time.

It's not your computer. :-k

Since you are attaching pictures, you are, indeed, limited to one per post. If you host your pictures at a public hosting site (Imgur, Photobucket, etc.), you can copy the IMG link and paste the link in your post. By doing that, you can do up to 10 pictures per post.

Tips when doing that:
- In Photobucket, you can set your preferences to automatically re-size uploaded pictures. I have mine set to 800 pixels on the long side. This has several advantages. 1. It saves space on Photobucket's servers and my space alloted on them. 2. It provides a decent size on virtually any computer screen, without scrolling to see the whole picture. 3. When someone loads the page, it loads quicker, because it's a smaller file.
- When posting links, be sure to press the ENTER key between links, to prevent pictures from stacking up side-to-side, which requires scrolling sideways to see them all. It also extends the lines of text in that post, making it hard to read. Even better is to hit the ENTER key twice between links. That gives a blank line as a border between pictures, making them easier to see.

.

 

[Michael]

Due to my schedule I am only now managing to remove the piston. Turns out the application of heat and gentle use of a mallet was key, obviously the inner sleeve had corroded to the cylinder locking the piston in place.

Thanks for all the suggestions! I can't wait to take it out tomorrow, after I bleed the lines of course.

 

[Gorminrider]

well, I'd be thinking you need a new master cylinder, really. otherwise you can try to hone the cylinder, given your description, but seeing as you aren't going into mechanics too deeply without a shop for a bunch of eclectic tools, a new one is best.
But, out there in the parking lot, I can imagine myself with a collection of wet+dry sandpapers and a dowel-to-fit too.. just be aware the piston cups need to fit tight and round. you don't want to take too much off the surface to get rid of pits or you'll be living life on the riskier side when you give those brakes a hard squeeze down the road...

 

[Michael]

I can imagine myself with a collection of wet+dry sandpapers and a dowel-to-fit too.. just be aware the piston cups need to fit tight and round.

That's exactly what I did once the piston was free, 400 grit to remove the "varnish" from the old fluid. The piston rides nice and smooth now!

 

[Gorminrider]

..... and it's just an aside but I remember in the olden-times something about oversized piston cups when I honed a car's wheel cylinder. Modern method is just to get a new assembly for all the work,danger and nuisance that too much fiddling will make clear- so if yours turns out to be beyond hope....

but it sounds like you "are getting away with it" ride on! (but gently at first)