Clutch piston cleaning and polishing?

Recently got the clutch slave cylinder apart to check seals and drain all the fluids to change them. Turns out it was full of gunk and needs a little cleaning up. I was thinking about taking a cloth wheel to the piston and polishing it up really nice before putting it all back in, is that a bad idea?

Also what engine case paint would you recommend to match the original finish since some brake fluid and coolant have ruined my day a little bit on the covers (clutch, water pump, etc)

 

Soak the cylinder in some seafoam and it should break up all that nasty stuff. Not sure what paint to use, but I know friends who have had luck with the duplicolor line of rattle cans. Good luck!

 

I used a metal finishing Scotchbrite pad to clean up the piston and cylinder when I rebuilt the slave on my 500, worked pretty good. PJ1 glossblack epoxy engine paint does a good job.

 

Creaky, is this Scotch-Brite 7445? Thx!

 

The ones I use are 7414. Using WD40 or an equivalent as a lubricant will produce a more polished surface but requires more elbow grease.

 

5x5, thanks creaky.

 

Well the piston and housing are both polished to a mirror-like finish after some double 0 steel wool and a little work.


But when draining the clutch fluid it started fine but after a few good pumps the lever lost all pressure and now won't pump any of the fluid from the master cylinder down the clutch line. Anyone know what the problem could be? Is it something stupid on my part or might it be time to rebuild the master cylinder?

 

A great item for the tool bin:

 

That's exactly what I was thinking. Usually I don't like specialty tools but that would make my life 10 times easier.

The only thing I'm concerned about is that when I put the new fluid in it wont have pressure at the handlebar and I'll have no clutch. Hence I would have to take it all apart again to fix it.

 

Its likely a large air pocket in the system, it is difficult to manually bleed a dry system, hence the mityvac. What you could try is gravity bleeding. Fill up the master, let the bleeder open, and go do something else for an hour and let it drip.

 

I am a fan of the Mityvac.

It is one of the best $25 tool investments you can make and makes bleeding hydraulic lines almost fun.

 

Well I have a big ass cooking syringe laying around, if that doesn't do the trick I'll order up a Mityvac and show this sucker who's boss.

 

You most likely have air trapped at the banjo fitting at the MC. Loosen the MC bolts and tip/rotate the MC forward so the banjo is below the bottom of the bowl. Then pump away.

 

Well, the thought has crossed my mind for a while now of finding a used master cylinder for the brake and clutch off of a modern bike possibly with the plastic reservoir with the screw on cap. My master cylinder reservoirs aren't pretty and the plastic windows on the front are cracked and cloudy.

Anyone know what a good bolt on replacement would come off of?

 

These systems can be difficult to get going after emptied, if you pinch the line just below the banjo fitting at the master and pump the lever it will build pressure and bleed normally.

 

Also helps to hold the piston fully retracted by means of a C-clamp while bleeding.....less space for air to hide.

You need to be EXTRA careful not to over-tighten the long bolts mounting the slave cyl to the sprocket cover or the rather weak mounting points on the engine case can break.

 

That seems pretty course for a cleaning. Not sure what grit the above grades of scotch brite that were mentioned.

 

Course? I believe 00 steel wool is the finest they make. I have some 2 grade steel wool and its much more course

 

Scotch-Brite 7445 pads (these are white in color) are equal to 1200-1500 grit paper.

I am not sure what the 7414 S-B pad rating is as I have not used these before.

I can say that the 7445 S-B pads work really well for polishing when used with WD40 (creaky mentioned he uses this same method).

For reference #0000 grade steel wool is equal to 500-800 grit.

As such, the 7445 (and most likely the 7414) pads are much finer and probably a better match when polishing machined surfaces.

 

Thanks for the reference info.