I’ve had to replace rear brake cylinders on a Classic Mini in less than a year.
I think there are several things that can happen …
1) A specialist and well respected classic brake refurbisher said that the seals swell slightly and if not used regularly then they will seize;
2) Fluid that gets past the seal to the outside, even a tiny amount, will absorb water and cause the rust under the boot then seizing through lack of use;
3) Components are simply not as good as they used to be!
I change fluids at no more than two years and often annually yet have still had problems. Over Winter I go in the garage weekly and give the all the pedals a good pressing. We had a problem getting my Son’s Elan going this Spring. We had to store it in a friend’s garage away from home for a few months and couldn’t do our usual pedal pressing. The clutch rusted onto the flywheel and pressure plate and I had to use a bit of brute force to jar it free!
