Topic: Having problems with a Master Cylinder rebuild cb550

[elquenada]

1975 cb550...brakes were working well but i had a small leak coming from the MC.  It was coming out of the side where the brake handle bolts on so I figured I'd better get a rebuild kit.

here's where im at. i removed the MC from the bike.  pulled out the rubber boot and im looking down at the plunger but I cant see the snap ring thats supposed to be there.  Theres a good bit of rusty colored gook down there.  I tried to scrape it off but i still cant make out a ring.  The plunger functions fine so it's not seized (but maybe the snap ring is?).
I tried tugging on the plunger and it wont come out on its own; the ring must be down there.

question:  What solvent (besides water) can I use to clean out the MC?  I dont want to use anything that might contaminate the brake lines and make them unsafe.  

[Kevin400F]

Here's a trick that works for me.  Clamp the master cylinder carefully in a vise or Workmate with LOTS of padding (you don't want to distort anything), reinstall the lever pivot bolt and use a slim screwdriver to hold the plunger down in the fully-depressed postion.  This will give you a much better view of the snap ring.  In my experience, the rusty gunk down there won't yield to solvent; you'll probably need to carefully scrape it out with a sharp pick.  Once you discover the holes of the snap ring, use your pick or a flat-bladed jeweler's screwdriver to clean the holes out really well. 

Getting the snap ring out is the most difficult part of the process.  You'll typically need a special long-reach snap-ring tool, and you may have to grind it/alter it a bit to reach the ring.  Having the plunger depressed as you reach in to release the snap ring helps a great deal.

[BeSeeingYou]

Did you get out the circular wire clip that holds the boot in place.  Sometimes pulling the boot out this slips off and stays in place.  It may be hiding the c- clip.  The c-clip is thin and can easily be hidden by gunk.  Try holding down the piston with some type of clamp (I used a allen wrench and small c-clamp).  It will relieve the pressure off the c-clip and allow for a tiny bit of movement and even allow you to spin it around.  Spay some Sea Foam or something similar.  Just don' use anything that will damage the aluminum like acids.  You will be cleaning and flushing the MC so not to worry about the brake lines.  Many of us have made special tools or using small screwdrives or picks to get the clip out but you can get the proper tool online for $10-20.  The ones at hardware and auto parts stores don't have a long enough reach.

[elquenada]

great tips.  thanks to all.

I can now actually see the c-clip.  it is hiding behind the goop and the metal retainer ring that holds on the boot. (i was wondering where that thing was!) 

i think im gonna grind down my cirlip pliers with my dremel; this should give me the extra clearence i need to reach the clip. 

[steamnjn23]

i have used rubbing alcohol for years to cleanup brake fluid residue. 

[mslaptoptx]

a set of small, long needlenose pliers works great to get the "c" clip out. I took and old pair and ground the tips to fit and it works like a charm. Of course the pliers the go in the "special tool drawer" for next time.

Mike

[elquenada]

thanks for the tip.  I just got the ring out using a "nut pick" a usefull tool ill be using in the future for sure.

I wrote it up here:

http://forums.sohc4.net/index.php?topic=67968.0