Had a similar problem. Turns out the rar calipers were upside down

Ok

Thanks everyone again for your comments .......here's the update

So - bled and then plugged the MC in the car (effectively closing off all four lines) and and the pedal is ROCK HARD after 1 pump. This i believe confirms its NOT the MC.

Bought a power bleeder, and as someone said, you'll wonder how you lived without it and ain't that the truth .... what a great tool.

I pumped it up to 25PSI and waited for 10 minutes - no pressure drop and as you'd expect with no pressure drop .....no leaks.

I then bled from the furthest - back left (RHD car in Australia here so MC is on the right) then back right then front left then front right. Changed colour of brake fluid so i could see when i was flushing no air and brand new fluid - pumped more pressure and probably pumped a litre (quart for you US people) more fluid through the system than i needed .........to just to be sure.

I still HAVE NO PEDAL AT ALL .........any ideas now everyone ??? its a complete mystery to me.......

At this point I would be looking at the motion of the pistons in the calipers. Maybe, for some reason, they are retracting too far. It’s a long shot, but if you’ve done everything you said I don’t see how it can be a hydraulic problem.

Oh and i replaced the front lines as well ..........backs are pretty new already

I was thinking Calipers too but that just doesn't make sense in a lot of respects ...

I will pull them off and have a look - i can't think of anything else to do at this point since as per my previous post everything is checking out from the resivoir right through to the bleed nipples .....

The other thing ...wd fifteen is if they were retracting they should push forward to the disk with a pump of the pedal and create a good hard pedal and draw more fluid from the resevoir in the process .......??

That said i'm going to look at the callipers since theres nothing else to check ........

Just checked the rear callipers

Clean, seals look good (only re built them 3 years ago) no signs of any leaks and move sweetly wiht a little compressed air .......

Check the fronts tomorrow night .......

I had bad seals on the calipers on my 77s and it still had great brakes.

when I run into a situation like this I have to assume "I" am doing something wrong.

Two ideas:

1) Have you replaced the flex lines? I'd do this first assuming they are original -- it's time.
2) Maybe you have some air trapped in the calipers -- you might try using your pressure bleeder with the calipers removed and manipulate them so that the air has no way to go but rise to the bleeder nipples. If you do this, make sure to put a block of wood in the caliper to keep the pistons from blowing out.

No, the fluid is drawn from the reservoir when the pedal is released. If the seals are sticking on the pistons, or the pistons are retracting too far for some other reason, when you release the pedal the MC bore is refilled from the brake lines when the piston retracts into the caliper, not from the reservoir. Like I said, it's a long shot. Don't take the calipers off, just watch each one when you have someone press on the brake pedal. You can see if they move in and out much. The motion of each piston and pad should be almost imperceptible.

You said the pedal was "rock hard after one pump" so I imagine the master cylinder is bad. It should be rock hard with NO pumps which is how you normally brake.....just push the pedal and after 1/2 inch or so the pads should hit the rotors soooooo that is not happening.

If it were me I would put some saran wrap under the reservoir cap to keep all the fluid from draining and then pull the master cylinder off the car. You can pop the boot off then remove the snap ring which is usually how the internals are held in. Let the fluid drain out then pull the internals to see what is wrong. There are diagrams on the net (not sure if any are here) so you can see what is supposed to be there and how it goes together. Good luck!

Ok everybody

Thanks for all your advice and tips

I FINALLY solved it. Not sure if i really want to admit and share it but will to save anyone else the time i've spent (wasted) on getting this sorted

I have S callipers on the front - they have 2 bleed valves - one on the outside and one on the inside of the disc / rotor.

I had forgotten this (haven't needed to touch my brakes for 3 years) and it isn't that easy to see ......The minute i saw it i knew that was the issue .......dohhhhh

Anyway, power bled the whole system, best pedal ever !!!

The bonus is i now own a power bleeder

Thanks again everyone for your ideas

Sorry, to clarify - there is a second bleed valve on the inside of the S caliber that isn't easy to see

One on the outside - i was bleeding from and forgot about the internal one

Had 2 big pockets of air on the inside side of both front callipers ..............

hate to quote myself but it is a great lesson.

I bet you have the cleanest brake lines with all the fluid you pumped thru them

Yep T77911S - i sure do and the best pedal ever !!!

I suddenly feel like quoting Monty Python.

"Australia, Australia, Australia.'' Yes, I went right to the end.

Thanks for giving us the update from down under.