Clutch Slave Question

[TheRepoGuy]

Evening Folks!
Now that the big **** on my old girl is pretty well handled (being as it runs) I’m turning to the little stuff that’ll drive ya bloody nuts and first is the slave cylinder. It looked like someone hadn’t cleaned their ears in years when I opened her up - full of aluminum oxide and crusty ass brake fluid. Pulled it off, cleaned it and noticed the piston inside the slave looks like it’s seized up. She won’t grab the clutch at all which is a minor annoyance ha!

SO - How does one go about unsiezing the piston from inside the slave or is it just better to buy a new one? Here’s what it looked like
Nate

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[GTC@MSAC]

You could probably still hook the line back up, bleed out the air, and pump the cylinder out just like you have it there. Then you can evaluate the condition of the housing and the piston.

 

[TheRepoGuy]

You could probably still hook the line back up, bleed out the air, and pump the cylinder out just like you have it there. Then you can evaluate the condition of the housing and the piston.

Tried it - the piston won’t move at all; doesn’t even grab the push rod. Bled it at the banjo bolt at the top and again at the bleeder screw on the bottom with no success.


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[GTC@MSAC]

You might not have a good master cylinder then either. I promise you, without any trapped air, and with a good master cylinder, you will be able to exert something on the order 400-500 psi on that piston. It will either come out or fluid will leach out around the piston seal, but sufficient fluid pressure will break whatever hold the corrosion has on the piston. If, not then you are left with replacing the entire slave cylinder assy. From the looks of the 1st pic, I'd bet the master cylinder isn't in much better shape either.

 

[joedrum]

Hmmm ...i Agree with with GTC

 

[pidjones]

Might be able to use the same trick we use on brake pistons - fit a gease fitting to it and pump it out with a grease gun.

 

[saganaga]

Before you mess with grease, have you tried compressed air? Quick to try, and a lot cleaner.

 

[GTC@MSAC]

saganaga » 04 Aug 2019, 22:34[/url]":1xseti0n]
Before you mess with grease, have you tried compressed air? Quick to try, and a lot cleaner.

Ohohoho! :shock: I have, on several occasions! If you've ever wondered "do brake pistons travel the speed of sound?", I can say they get close enough to count! :whistling:
Fluid and/or grease pressure is mush easier to control, lol! :mrgreen:

 

[saganaga]

GTC@MSAC » Yesterday, 9:23 pm[/url]":1m63bko5]

saganaga » 04 Aug 2019, 22:34[/url]":1m63bko5]
Before you mess with grease, have you tried compressed air? Quick to try, and a lot cleaner.

Ohohoho! :shock: I have, on several occasions! If you've ever wondered "do brake pistons travel the speed of sound?", I can say they get close enough to count! :whistling:
Fluid and/or grease pressure is mush easier to control, lol! :mrgreen:

Well, I'd have suggested aiming it into a soft towel, or throwing an old sock over the end of it.

But I do understand the appeal of making projectile weapons.

 

[TheRepoGuy]

You might not have a good master cylinder then either. I promise you, without any trapped air, and with a good master cylinder, you will be able to exert something on the order 400-500 psi on that piston. It will either come out or fluid will leach out around the piston seal, but sufficient fluid pressure will break whatever hold the corrosion has on the piston. If, not then you are left with replacing the entire slave cylinder assy. From the looks of the 1st pic, I'd bet the master cylinder isn't in much better shape either.

In an odd twist on this bike - the brake and clutch masters are not stock and weren’t when I got the bike. Look like a cheap aftermarket part honestly. I bled the system at the banjo bolt on the master then again at the slave; left with replacing the master likely with the ones I had taken off my Valkyrie before it was totaled out a few years ago. Might go ahead and replace the slave anyway since it’s pretty nasty inside all things considered. I have thought about trying the grease trick to see if it’ll work but haven’t done it as of yet - still letting it soak in PB blaster just to see if it’ll free up but I’m not super optimistic about it.


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[TheRepoGuy]

Before you mess with grease, have you tried compressed air? Quick to try, and a lot cleaner.

I’ve done that as well - broke a window in a garage doing that once or twice ha!


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[pidjones]

I don't understand the aversion that some have for grease. You are going to have a much nastier cleanup from just the brake fluid and corrosion than the grease will present. A couple paper towels has always removed 98% of the grease for me, just leaving the bleed and supply holes (plus cross-over for the rear) to flush with a shot of brake cleaner. Then comes the long process of piston ring slot cleaning.

 

[TheRepoGuy]

I don't understand the aversion that some have for grease. You are going to have a much nastier cleanup from just the brake fluid and corrosion than the grease will present. A couple paper towels has always removed 98% of the grease for me, just leaving the bleed and supply holes (plus cross-over for the rear) to flush with a shot of brake cleaner. Then comes the long process of piston ring slot cleaning.

Anymore - there’s nothing that’s too “long” of a process with this machine; as long as it works I’m good!


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[Ansimp]

pidjones » Mon Aug 05, 2019 12:10 pm[/url]":3u2c694i]
Might be able to use the same trick we use on brake pistons - fit a gease fitting to it and pump it out with a grease gun.

+1 :good: much greater pressure. They are going to need heaps of cleaning anyway.

 

[TheRepoGuy]

My PB blaster trick worked to unfreeze it up; it’s been soaking in white vinegar overnight. The whole thing needs to be completely scrubbed down which I’m going to do this morning and then buy a rebuild kit I think. My only issue is the inside of the housing where the piston sits doesn’t look to hot. I’ll post pictures of it in a few, the one below is from when I first dropped it in the vinegar
Nate

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[TheRepoGuy]

Here’s the look after a 24 hour white vinegar soak. Still needs a little cleaning but nothing compared to what it initially was!
https://youtu.be/KTpDSQG_a5U




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[saganaga]

Try some crumpled aluminum foil and a weak acid (like the vinegar you used) to clean that roughness on the inside. It may work, and crumpled aluminum foil is very gentle on surfaces.

 

[TheRepoGuy]

Try some crumpled aluminum foil and a weak acid (like the vinegar you used) to clean that roughness on the inside. It may work, and crumpled aluminum foil is very gentle on surfaces.

I went and got some 1000 grit wet sand paper which I’ll give a shot to it tomorrow morning.


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[DaveKamp]

I have an ultrasonic cleaner... bigger than the average 'jewelry' type cleaner, came out of a laboratory, the tank has about a gallon liquid capacity... tank is stainless, and heated.

I've used white vinegar, as well as other stuff, to clean anything from carbeurator bodies to jets, needles, and floats, master cylinders, small pistons, compressor valves, even radio parts (bread-slicer capacitors). Of course, different materials require different agents.

Initially, i'd put cleaning agents IN the tank, and after a while, I stopped doing that, partly because the tank got so nasty... and partly because I got tired of dumping out whatever agent I was using to switch to a different agent, and finally, I got tired of dumping it all out and fishing out my small parts from the bottom of the dirty goo. Now, the tank always has distilled water in it, but it's only about 2/3rds full. What I do, is place my parts in ziplock bags, and pour in whatever agent I need, into that bag. Then I zip it shut, put another bag over it, zip it shut, and drop it in the tank. Ultrasonic waves pass right through the bags, into the agent, and parts. I can drop four bags, all with different parts and agents, into the tank, and do 'em all at once. Residual air bubbles in the tops of the bags keep the tops of the bags up, and suspend the parts and agents in the middle of the tank, rather than falling to the bottom. The only agent I deal with, is what little is in each bag, and it's usually so small a quantity, that I don't lose much even if I throw it out after one use.

I'll be doin' this with my Aspy's clutch slave sometime here soon.

I'm curious... is the bore of the GL slave cylinder plated, or anodized in any way? If so, pitting in that anodizing means scrubbing it clean will increase the ID. The OD is dirty, but aside from properly registering and sealing the mounting hole against internal lube leaks means that OD is not substantially problematic if you abrade it back a little... but the ID around the piston sealing edge will be a different story... it'll probably bind...

 

[TheRepoGuy]

I think the inside is just chromed or something similar like a hydraulic piston would be - unfortunately the ultrasonic cleanse didn’t do a thing for my slave, Mine was too far gone to make it worth while so I ended up buying a new one.


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