Just replaced 3 wheel cylinders and now the pedal goes to the floor without pumping

My 1974 Series 3 sat for 2 years before I fired it up again last week. Lo and behold 3 wheel cylinders immediately failed upon my first drive. Made for some interesting stopping with only one brake working. I got under it and replaced the 3 cylinders and thought I bled the system adequately. One thing I noticed though was that my front drums seemed to be heavily worn, since I could barely adjust the shoes to grip the drums with the adjustment screw. Before the cylinders failed I had only had to slightly pump the brakes to get a firm pedal, but now I have to pump it a good 3-4 times with the first pump going all the way to the floor. Also, on snow, the rear wheels will lock up first with the first pump before I get a firm pedal. Seems like pressure is going to the rear before the fronts are getting any pressure. Would this be my master cylinder going bad or do I just need to bleed the system more? Thanks again for any info.

:welcome2:
My money is on the master cylinder, they're very cheap and easy to replace.

Rob

Have you got twin circuit brakes?

go on ,go for it buy the fourth..............then you've got a matching set.
now buy an eezi bleed kit.....makes it so much easier.if you want perfect brakes ( impossible on a series) sounds like you need new drums as well!!plenty of brake fluid and your away.stops on a sixpe er well on a good size runway,lol. have fun.

you can check where the problem is by clamping the flexi hoses 2 at the front and one on the rear, check the pedal if still spongy then suspect master cylinder seals, if ok remove rear clamp, if still ok then its one of the front where the problem is, remove a front clamp and that will tell you which side.

if the wheel cylinders failed , are the linings all oiled up,
just did the fronts on mine last coupe, of weeks, new wheel cylinders, shoes, drums, evn though not yet bedded in under braking the bonnet dips about 3 inches!!

i used an eezi bleed too well worth it

Thanks for all the info, I'll dive back in and try some of those recommendations.
And yes, it has the twin circuit brakes.

You say you can barely adjust the adjusters tight,firstly do a test and put a small nut,that fits snugly over the adjuster post on the post,you will then be able to adjust all the adjusters tight,if you still have to pump the pedal,look for air in the system!

AKRover said:

And yes, it has the twin circuit brakes.

Click to expand...

Did you bleed the brakes in the correct way, if you do one wheel at a time it can cause the shuttle valve to move across (it will think there is a leak in one of the circuits, so close it off, the point of twin circuit brakes) and so you will only get braking at one end.
Sorry I only have single circuit so apart from being aware, I can't help further.

That sounds like what I did wrong. Is there a way to shut off that valve or is there just a certain procedure to bleed it to prevent it from opening? I'm looking at the haynes manual now and it looks to be procedural.