Morris Minor Owners Club

My brake pedal moves about 1/2 way before it goes solid. Time to adjust brakes I thought. So I did and even fitted a couple of shims on back of rear cylinder, to take up some play. Pedal still goes 1/2 way down. It is not spongy, so that should rule out air in system. Only thing left is master cylinder. Do my symptoms point to that being the problem?

Depends. if the pedal movement decreases on the second push on the pedal then the shoes are too far away from the drums. You could also have a problem with the rubber valve in the master cylinder which maintains a pressure of approx 8lbs in the system but this would be rare.
This valve is removed when disc brakes are fitted which results in more pedal movement before the brakes bite. If you do not have discs then this does no apply in your case. Shims on the rears? Where and why?
It is important to adjust the rears with the handbrake cables slackened off at the handbrake end first.

How much free play in the pedal before it starts to push the master cylinder piston? It should be 3/4 inch. Use finger pressure to feel for the free play portion of travel.

Another possible fault is the master cylinder pushrod bends. So check that's straight as it adjust the free play.

When master cylinder starts to fail, the pedal is normally spongy, or rock hard at the top if the piston has seized.

Might be worth bleeding the brakes thoroughly , brake fluid might have absorbed a lot of moisture over the winter.

Does sound like it just needs further adjusting up ( and yes I have used shims on the rear) or bleeding -but is this a new problem -or has it been like this since you fitted the Riley drums ?

Willie, definitely NOT discs.
Roy, the pedal was quite high when I first fitted the Riley drums. One thing I have found is that when shoes adjusted up solid, I have to take each shoe off about 3 clicks to stop it rubbing. This may be due to the different adjustment method. Will try bleeding it all again to see if that makes any difference.

Ahh -well 3 clicks off is too much. Can only suggest you try with different settings to get a good compromise.