Brake problem (almost everything replaced still a soft pedal)

If I thought there was play between the booster and the MC I’d plug the output lines of the MC and see if the pedal still felt soft/low. If so, then too much space there would be a likely cause. If the brake pedal was firm with the MC outputs plugged, then that couldn’t be the cause.

i did plug the mc on both outputs and pedal was hard…thanks

also one other point……… I had a good pedal before all this started… I only replaced the calipers and rear brake cylinders to make sure I was new before summer ,and then this problem occurred

ok so the front brake hoses were replaced then power bled… there a little better but not rock hard and the pedal still goes down 1 " from floor after pressing. Theres nothing else to replace

Just loved this post…it proves our engineers at the UAW are flunkies…
I assume all the posts below are very accurate. they all achieve some degree of firm pedal on most cars.
So my suggestion is quite different …on the impossible to bleed cars.

by placing a tire lift or car ramp under the drivers rear tire…lift it very high…then start the bleeding process on the lower side right rear.
whats happening is air traps at the very top of the rear cylinders, the bleeder is lower than the air.
so no amount of pneumatic bleeding or regular bleeding will vent this air.
by lifting the opposite side of the car then bleeding the lower side. this clocks the slave in a upward stance
so the bleed port is higher than the air…
do this opposite tire as well…there is no need to do this on the front…if its disk.
Ive never found a disk to be engineered wrong…but slave cylinders YES.

Ive also cured air trapped at master cylinder installs…by lightly tapping the pedal for about 5 minutes after a master install there is no need to do a 4 wheel bleed afterwards.
the check valve returns all the micro air back into the master and its all good to go in about 5 minutes.

motorcycles are specially a bear…you have to tip the bike and use wrenches to tap the lines all the micro air quaglates to one big ball and then it bleeds out.