Morris Minor Owners Club

Can anyone advise what I need to replace brake master cylinder on a 1966 Traveller please. Is it a question of replacement or can these be reconditioned with a kit. After taking of the plate cover its wet in there and just think it may be leaking. Many thanks Tom

Maybe you should check the brake pipe connections for the leak, before condemning the cylinder. If you’re convinced the cylinder is the problem, I’d suggest replacing rather than a repair kit.

As Les has said, check everything else first before diving in to replace the master cylinder. Is it just damp in the chassis leg or swimming in brake fluid ? Most chassis legs are 'damp' in there, years of people spilling fluid when they top up,but if it's very wet, you've probably got a leak. Unless you have a servo/disc brakes fitted, there should be two pipes leading from the rear union, check for leaks there.

If it is the master cylinder then again as Les has suggested, fit a new one. You can get seal kits but, it's a big job to change, so easier to go for a new one. There were two bore sizes, early cars were 7/8 and later ones were 13/16. You can only buy 13/16 cylinders now. Search the mechanical section for hints and tips on fitting.

I had brake pedal problems, and found the entire box section about 1-2 mm deep in fluid. The MC was leaking at the plunger end.
Note the mess inside the rubber end cap.
You can disconnect and remove the plunger while the MC is in place...
. I did examine the bores carefully and chose to try the overhaul kit first rather than replace.
It seems to have done the job as the brakes still work, with no leaking.