I have a couple of questions about brakes please:

(1) I have an old (1980) bike with a single disc, fixed caliper, single piston (well, one each side of the disc, I think that counts as a single piston). The bike is known for not having great brakes, partly due to the master cylinder bore being a bit too big.

Replacing the entire setup is unlikely to be an option, so I think the only thing I can do to improve things would be to fit a braided brake hose. Anyone think thats worthwhile? The Internet seems to think gains will be barely noticeable.

(2) How important is the lid seal on the brake fluid reservoir – should it be capable of holding pressure, and should you ever see fluid flowing back into the reservoir? At the moment, if I have the lid off, and squeeze the brake lever, I can see fluid being pushed back into the reservoir, so its possible the master cylinder is failing.