For such small components, there is a lot going on with the braking system and it is taking a while to get through the investigation and cleaning of all of the pieces. Next up is the rear master cylinder and there aren’t many OEM parts available for this one, so if things look ok, the plan is just to put it back together once it is cleaned up.
Simple looking device. Brake pedal applies pressure to the piston, which puts pressure on the brake fluid, and then pushes the brake pads against the rear brake rotor.
Once you get the boot out of the way, there is a snap ring that holds in all of the guts of the master cylinder.
Keeping some pressure on the piston while removing the snap ring with the appropriate snap ring pliers and it comes right apart.
Here are all of the pieces that are inside the rear master cylinder.
After a little bit of cleaning, everything looks pretty good in the rear master cylinder. I’ll probably throw the piston in some parts cleaner before putting everything back together.
One thing you do want to do though before you put everything back together is make sure that the very small brake fluid return hole is clear. The brake pads will drag or worse if this return hole is not clear.
My intent was to get started on the front master cylinder next which has a very similar construction to the rear master cylinder, but the snap ring is much deeper in the body of the front master cylinder and my snap ring pliers can’t get in there. Time for another tool… (Wet and shiny due to the PB Blaster that I sprayed to make sure the snap ring was not corroded in place. A broken snap ring will not be fun.)