I'm losing this battle with the rear master cylinder

[akinz]

I spent hours trying to remove the rear master cylinder bits for a rebuild but man... it's past seized, I think more like welded.. air pressure, penetrating oil... no give.

Any suggestions? I'm Soooo close to being able to take this thing on its first run but I have to get this done!

[Goss]

Force grease through it using a grease gun, be prepared for when it pops!

Regards

Goss

[tevan]

Force grease through it using a grease gun, be prepared for when it pops!

Regards

Goss

Get a bolt the same size that screws in where you attach the rear caliper hose and drill a hole all the way threw it and tap a zerk in it and pump the grease to it. It will push it out.

[steve murdoch icoa #5322]

Have you tried boiling water and/or a heat gun on the outside of the body.
Of course the heat gun might requie a repaint.
I have also seen a method of drilling, tapping and then using a screw as a puller, obviously requiring a new piston.

[Z Grand]

I have also seen a method of drilling, tapping and then using a screw as a puller, obviously requiring a new piston.

I tried that method and still could not get the piston to budge. Sent it to a friend who used an old master cylinder and brake fluid to pump the piston out.
Here was his method:
"The first thing that had to be done was come up with a way to block off the fitting where the reservoir supplies brake fluid. That was easy - I used one of my silicone rubber plugs:

Then I hooked up my vice-mounted master cylinder, filled it with old brake fluid, and started pumping.

I had to occasionally crack the banjo fitting while holding the brake lever so that it would purge the air bubbles. Then I started feeling some pressure and within a minute, out popped the piston."


Hope this helps. Of course, you'll need an old master cylinder assembly you can use for a pump.

[tevan]

I made a cap out of steel where the plastic fitting was. It got sealed tight. Then the grease gun trick.

[daves79x]

You can drill it out also, but be careful.

Dave

[akinz]

Guys... Thanks so much for your help!

It came out without a problem with the grease trick!!! I used an old brake line bolt I had and drilled a hole straight though it then tapped and installed a grease fitting. Used a couple extra washers and had to cut about a half inch off the bolt so I could put it in far enough the washers would cover the brake line end of the whole.

It is now part of the CBX tool club hahaha




Now on to blasting, painting and rebuilding