Thanks for the replies!
the brakes just lock up after a while driving, when I want to stop the car. Yesterday I drove 30 miles without any problems, but when I came home and wanted to drive her in the garage, this problem occurs, and it locked up so fearce that I was afraid to break a drive shaft. I already gave the pedal more space before it realy brakes, but this space is gone when the master cylinder locks up. It is surely the mastercylinder, when I jack up the car all four wheels are locked up.
I drove the Chrysler for several years without any problems on silicone with new wheel cylinders, new lines and an overhauled mastercylinder and the car always really braked very well.
The mastercylinder is the round type with the reservoir separate , but I think that I can shut up this reservoir when I use the master cylinder with the reservoir on top of it., like the one on the Dodge WC. The holes to mount the cylinder seem to be the same .