When confronted with the rear brake staying on, many owners tend to immediately blame the hydraulics. While this may well be the cause, it could equally be a purely mechanical reason.
Due to the position of the brake pedal and master cylinder, the pedal pivot and the linkage get totally forgotten in the maintenance schedule.
Not easy to get to, and mostly hidden by the side panel, exhaust pipes etc., it's easy to see why.
But for precisely the same reason of position, they get covered with dirt, debris and soaked in the rain, making them a prime target for some serious rusting.
When I first got the Swan, the brake linkage was so rusted at the master cylinder clevis pin that there was NO movement at all! I had to remove the brake pedal and master cylinder as one unit and hammer the pin out!
Fortunately, once the clevis and the brake pedal had been de-rusted and cleaned up, there was little wear in the pivot holes. A new pivot pin and we were good to go with the rebuilt master cylinder.
But how to stop this mess re-occuring?
First of all, the brake pedal pivot hole had a chamfer put on both the ends, the pivot cleaned up and the pedal hole de-rusted.
A thin 'O' ring was slipped on to the pivot, the pivot well greased with a copper based grease (that is what looks like rust in the pictures), another 'O' ring slipped on the outside and then the big washer and split pin. The idea being to seal out the water in the first place. The 'O' rings were thick enough to just be causing a slight drag on the pedal as it was moved
To seal off the clevis I used some self-amalgamating tape such as electricians use and fashioned it into a sort of boot around the clevis. Obviously it needs to be loose enough for the linkage to move, but tight where it is wrapped around the pedal and the top of the clevis. With plenty of grease in there, that should last for a good while.
While we are still in this area, you can note the adjuster and lock nut. This is where the pedal height is adjusted from before you wrap up the clevis. Undo the locknut and with the clevis pin removed, turn the clevis clockwise to raise the pedal, anti-clockwise to lower it. Remember to do up the locknut afterwards!
Also note that the master cylinder mounting bolt holes were filled in from the back with some epoxy filler to try to stop water entering and causing corrosion.