Clutch Master cylinder .....as usual need some advice!

Odie1

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Claremore, Ok
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3876
Well, here I am again. Went for a short ride last Friday and after I had been home a while, walked by the bike and and saw fluid dripping out of the clutch master cylinder onto the left hand cowl. Bummer. And if you never really believed brake fluid won't remove paint, let me assure you, it does.... double bummer.

After checking everything, I see the fluid is coming out of the what the parts fiche calls the "piston set" ... the parts group labeled as #3 below. I have removed the MC from the bars, and the lever along with parts 1 and 2, but cannot see how you remove the piston set. I see there is snap ring (#19) but for the life of me see no way to get to it. Ideas?

Maybe I should back up a step and ask if the thought is that is actually where the leak is? I cannot tell from the parts drawings if there are seals on that piston set or not, I am only assuming there is since with the push rod removed (#1 - that does have an o-ring, but, I assume that is just a dust seal) all the fluid does not flood out, and you can work part #3 in and out with a small shaft.

Anyone get to have this fun before... and come up with a fix? Little surprised as that part (#3) lists for about $60 the first place I looked. Wow!..

Or worse - am I going to be looking at sourcing a complete master cylinder...new or used?

Anyway - thanks in advance...

Odie1



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Dbar

Dbar

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You need a decent set of snap ring pliers to get the c-clip holding the piston assembly out. After that, it's a piece o'cake.
 
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Odie1

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Nice- exactly what I needed. I'll give it a go this evening once I get a chance...

Thanks !

Odie1
 
Gus1300

Gus1300

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I just did this a while back on my 1300 clutch MC, the piston seals are VERY small compared to the diameter of the piston area they have to cross to be properly located. I was concerned about them breaking from being stretched too much, or compromising the sealing surfaces with whatever tool I used to try to get them across the multiple ridges, etc. Note the orientation (cup facing pressure) of the ones you take off, and also (don't ask my how I know!) the orientation of the push-rod, ie which end goes into the bushing and which end seats against the piston (interface between parts #1 and #2). The end are not the same (one rounded, one square) and will affect the overall resting position of the piston once the clutch lever is returned to its proper location. See https://www.st-owners.com/forums/threads/my-maintenance-and-upgrades.172294/page-2#post-2361075 post #32 onward for more details.
 
jfheath

jfheath

John Heath
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Make sure that the seals go into the bore with the flared (open) end leading the way. If they invert, they will not seal or work. You may need thin strips of (eg plastic) to help guide them in.
 
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Odie1

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Thanks for the tips all, will be heeded....

But of course, nothing is ever easy. Got a set of snap ring pliers from Harbor Freight and the "fun" began. Now, I know some HF stuff is pretty good, while others... not so much. The jury is still out on these, but leaning toward the later

Seems where the "opening" of the snap ring was could not be reached with the pliers. What I call the housing or flange on the MC that covers the actual clutch lever would not allow me to get there.

No problem I tell myself, I will just spin the snap ring around with a small screwdriver where the opening is on the other side and get it from there.

Who knew a snap ring that had been in place 26+ years might not want to move...easily... or maybe, at all ?

Anyway, finally got everything extracted and noted the direction everything came out.

Now, while waiting for the parts, I really need to clean the inside of the fluid reservoir, as it is all " crud-ed up". Is there anything I need to stay away from - chemical wise, or just get after with whatever works?

Odie1
 
nicksacco

nicksacco

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I'd consider checking/replacing the clutch slave as well.
I've rebuilt some, but replacement was about the same cost and no "dirty work".
If you do a search on clutch slave, you will find good info on here.
@Igofar has lots of good advice on this site including tools needed.
It most certainly can be done while engine is in the bike.
 
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Odie1

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John O...

Yeah - those look a little higher quality than the ones I got.... and I should know that by now... "Do not try and go cheap on tools"..


Odie1
 
Larry Fine

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Same here, but not so much in recent years.

Long time ago, I bought a can of Sears 'economy' ceiling paint. No matter how many times I went over it, I never could get a solid coat that looked one color.

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Dbar

Dbar

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If you need to lubricate anything on re-assembly I suggest you use brake fluid, not anything oil based. I think I bought my replacement slave cylinder from Partzilla. About 100 bucks, two years ago. That's a whole new bag a worms you may want avoid unless it's leaking.
 
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Odie1

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Sorry for the delay folks, other life issue have really been interfering with motorcycle time lately.

I did want to report back that I finally got the parts ordered, and after cleaning up the master cylinder as well as possible (still can get the 'stain' out of the sight window) reassembled.

All is well - did a short test ride one afternoon and spent most of they day out Saturday, and all is well. no runs drips or errors...as least yet.

One thing that did surprise me a bit was even after having removed the hydraulic line from the master cylinder, I didn't have to bleed at the slave. Once I reassembled everything - except the fluid cover, I worked the clutch lever - SLOWLY... and watched a few tiny bubbles come up. After doing this for like 10 straight minutes, and probably a hundred or more squeezes, all the bubbles stopped. A cautious test before and after starting the engine confirmed the clutch was working as normal.

Anyway, as usual, thank you everyone for all the pointers and tips.

Odie1
 
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