As mentioned previously the pin will set in the proportioning valve and shut off the rear because it senses a failure and is doing it's job. I found a fairly simple solution when installing all new parts and all the lines & cylinders are dry. I use a small pump type oil can with brake fluid in it. Remove the line from the prop valve outlet, crack open one wheel cyl bleeder, pump the line full, close the bleeder and do the other side. Hook the line back up and bleed the system. It saves a lot of hassle.
Fred
