Been putting discs on the 55 Chevy, used a CPP M/C and a Speedway prop. valve. The rear brake cylinders were toast, so I replaced them too. Now the rear brakes will not release unless I open the bleeder valve. What do think is the problem? I have bled the M/C and entire system several times, and can't figure this out unless the M/C or the prop. vale is faulty. Thanks.