Cleaning up the brake master cylinder and removing the insides


I removed the brake master cylinder on Saturday, and it was in a state, rusty as can be, it almost looked useless, but today I decided to have a go at cleaning it up to see what condition it was in.

Note: Use eye protection (protective glasses) during any wire brush usage.


Cleaning up the brake fluid reservoir

To start off with though,  I gently removed the brake fluid reservoir from the metal holder, I didn’t want to break it so I was careful. Once out the reservoir looked caked in rust and grease.


After scrubbing at it for 15 minutes or more with soapy water and a not-so-harsh scrubbing sponge I got it to look like this, much better.


And here’s the metal holder before cleaning with a wire brush.


sitting beside the brake master cylinder…


Next I started cleaning the brake master cylinder, to my surprise I could get back to metal after using a wire brush connected to my drill.


And I could see that there was a metal ring covering the perished rubber, so I removed that part and stored it safe for later cleaning.


I then used the drill+wire brush attachment to clean deeper into the metal taking care not to damage or touch the inside of the cylinder (as that will be honed later).


You can see straight away that this part is actually starting to show some life again ! Here’s a closeup of the end of the cylinder with the ring holding the inside bits in place.


After a lot more cleaning and the cylinder looks like this.


It’s not perfect but I don’t have access to a sand blaster, my neighbor does though so I might finish it off there later this year. I attempted to remove the brake bleeder and actually got it turning, and out!


I will replace that part of course. Here’s the cylinder after some more cleaning.


Next I removed the ring holding the plunger in place using a flat edged screw driver.


And stored it in an empty and cleaned ice-cream tub along with the ring and some perished rubber which needs to be removed.


After pushing the plunger it moved, and out it came, what a pleasant surprise, but there are more bits stuck inside, I need to remove them with care to avoid damaging any component.


Here’s the plunger with perished rubber slightly attached.


And then I got the spring and other rubber bits out, although by the looks of things this cylinder was out of action for some time, the rubber seal was out of position and wrapped around the spring.


After cleaning those bits look like this.


I’ve already ordered new rubber seals.

Here’s a closeup of the brake master cylinder with all the insides out, how excellent !


Yes it’s rusty and needs honing, but that’s for another day. The ‘wet’ look is diesel.


I’ll just leave these metal bits in the diesel bath for a few days, notice that the brake line is also cleaned up somewhat.