Morris Minor Owners Club

had a funny experience the other day when my morris was pronounced fit again by the garage after a minor electrical tweak to fix a broken connection. set off, applied the brakes, and the pedal went straight to the floor. nothing. even by a moggie's braking standards, this caused the driver some minor concern. it turned out the master cylinder had split, and the garage said that because it feeds all four wheels at once (apparently modern cars have dual feeds) then a collapsing master cylinder means total brake failure. without warning. not a comforting thought. so is there no way at all of detecting when this might happen? after all, the master cylinder is just like any other part, and prone to wear out.

Very unusual failure - normally get some warning such as low fluid level and/or spongey pedal due to weeping seals.

It could be adjustment, can the pedal be pumped up?

Do you mean a pipe from the master cylinder had split?

les wrote:Do you mean a pipe from the master cylinder had split?

i think he is saying for the seals in the main master cylinder that they are weeping/worn seals their may be a seal leakage at one of the brake piston.....but i would also say there could be a leak any of the pipes if its rotton.....i assume that the pipes havnt been replaced recently so that there is a chance that they wasnt done up tightly enough & leaking from their or getting air into the system? also has minor_hickup says if adjustment is not right can make a difference ....i recently found out that the adjustment nut at the pedal rod where it pushes the rod into the master cylinder was out of adjustment which can cause the wrong pressure, i would check all what has been mentioned & maybe a general check over the complete system and you should find the problem which is not a bad thing to do with cars....also while i think of it is how old is the brake fluid & any air in the system?

i think the mechanic said that the seals on the master cylinder had gone. in any event, he found a new one (amazingly enough) at one of the big local parts specialists, and fitted that. no mention of pipes. now it's fixed, the brakes also come into play at the first touch of the foot, rather than, as was the case before, about a third of the way down to the floorboards.
all seems well, anyway, although if what the garage said is correct (ie a master cylinder problem can lead to immediate total brake failure as a morris part pumps to all four wheels at once and not with a dual circuit) it doesn't quite make for carefree motoring when you're biffing down a country lane. in my case i was edging out of a car park, rather than, happily, heading for a T junction at 40mph.

regular checking of the fluid level normally gives an early warning.

I had a total brake failure at 40mph last month - heading for a read traffic light. Fortunately being used to driving Minors, I was slowing down well in advance using the gears, and handbrake works correctly so the loss of brakes was no problem. This was late at night! If it happened during rush hour it would have been a different story

I had the one of the rear brakes jump off its snail adjuster while fast approaching a T junction. I wasn't as prepared as I should have been...quite hairy. But my fault for not replacing a worn adjuster.

Docgibbons, that is correct, the Minor system works on all four brakes from the Master Cylinder, dual circuits hadn't been heard of in those days
you have to yank on the hand brake in the event of a failure.

Willie wrote:you have to yank on the hand brake in the event of a failure.

Probably better to firmly but gently apply it than yank it - How many drivers know how to control a locked rear end?

I was thrown by your post saying the master cylinder had split! Being cast iron I thought this nigh on impossible.

Packed up, brake failure has happened to me and believe you me you
don't have time to 'gently pull on the lever' when you are heading towards a T junction at a rate of knots.

A good hand-brake induced spin is the best way to lose the forward momentum! Of course - it assumes a good handbrake that can lock the wheels - which it should.

Hmm... my handbrake doesn't provide anything like the effort required to lock the wheels at speed, yet it's never required attention for the MOT.

Maybe you have nice grippy tyres! But still - it should lock the wheels.