Morris Minor Owners Club

Brakes all of a sudden went to the floor with near enough no effect. They stiffen up and come back a little again if pumped and stay firm, fluid level is ok, any suggestions?
Were working fine before

Have you checked the brake fluid level?? Check that, then, if low, look for leaks for a start off.

As ManyMinors. If nothing amiss, you have a failed master cylinder.

ManyMinors wrote:Have you checked the brake fluid level?? Check that, then, if low, look for leaks for a start off.

Fluid level is fine

Is there any history to this? i know you say "all of a sudden" but has any work been carried out on the system recently? Is it a standard drum set up or has it been modified in any way? Is there a remote reservoir, or is it the standard master cylinder? The fluid is OK now, but has it been topped up recently? The fact that you say that the pressure comes up with pumping and then stays firm suggests that there is no leak, which leaves air in the system or, as above, failed master cylinder.

simmitc wrote:Is there any history to this? i know you say "all of a sudden" but has any work been carried out on the system recently? Is it a standard drum set up or has it been modified in any way? Is there a remote reservoir, or is it the standard master cylinder? The fluid is OK now, but has it been topped up recently? The fact that you say that the pressure comes up with pumping and then stays firm suggests that there is no leak, which leaves air in the system or, as above, failed master cylinder.

Hi there, brake cables etc redone around a year ago probs now, standard drum brakes & MC. Fluid not been topped in a while, will be having a better look at it today and hopefully get it sorted

If the fluid isn't dropping at all, but the pedal suddenly goes to the floor, it's almost certainly a shot master cylinder.

i.e. fluid bypassing the master cylinder piston seal.

Most other possibilities would result in fluid being lost.

if your master cylinder is at fault,(as above rubber seals not holding the pressure,) you will have fluid loss,but just look underneath the car at the chassis below where the master is, since a failed one lets the plunger go right down but as is comes back up it pushes fluid out of the open end of the cylinder which then runs into the chassis leg and runs out of the drain holes. or take the inside cover off and you will see inside the leg from above,any sign of fluid and its the master seals gone. Air in the system seldom causes the pedal to go right to the floor ,but it can,air normally causes a spongy springing feel because air can be compressed ,fluid can't . If there is no sign of fluid at the master/chassis and when you pump you get a firm pedal,then likely that the brake adjustment has slipped,pumping causes the shoes to be pushed out to the drums and then you get the firm pedal. If you get a firm pedal and press and hold as hard as you can, a failed master will show as the pedal slowly sinking to the it will also show any leaks round the rest of the system. However its normal for the symtoms you have after the car has stood for a while because the system is designed to hold a low pressure which holds the shoes out towards the drums,after a long stand sometimes just overnight the pressure drops ,the shoes draw away from the drums and it take a few presses to get them back out where they hold with the renewed pressure. good luck