brakes update!!

[xtrememopars]

So since the last time i posted on here i had that issue with brakes here http://www.challengerforumz.com/archive/index.php/t-91417.html

so I replace brake master cylinder , booster and 1 rear wheel cylinder that was leaking. so i took it out for a drive yesterday and all was fine all of a sudden the rear brakes starting locking up until the would not move any more. i had to bleed the master cylinder to release pressure to disengage the rear brakes. any idead what is going on?? it cant be the master cylinder or the booster they are brand new any ideas??

[Bullitt-]

not sure if this would apply only to the rear brakes but if the rod from the booster to the master cylinder is to long the pressure is not completely released and with several cycles will build up enough pressure to hold the brakes on. The length is adjusted by removing the m/c and turning a nut on the end of the rod, somewhere I read a spec. on the length will make a search. 

[Bullitt-]

http://www.cuda-challenger.com/cc/index.php?topic=85566.msg855090#msg855090

Shorten the rod a full turn or so , it should touch barely in the back of the master , did you replace springs on the brake shoes , the springs may not have enough pressure to overcome the the residual pressure valve in the master cylinder .
 Maybe the booster is not repaired properly , new doesn't = right

[xtrememopars]

Thanks Ill check it out this weekend. anything thoughts that the proportioning valve can cause this problem as well?

[Chryco Psycho]

either could be the problem , if the piston is depressed in the back of the master the brakes will stay on & the fluid will not return , but the porp valve coul dbe preventing the fluid from returning also

[xtrememopars]

ok I am gonna end up taking the prop valve out soaking it in evaporust check the rod in the master cylinder and bleed the brakes according to the book. if that dont work i have no clue what is going on.

[73EStroker]

taking the prop valve out soaking it in evaporust

Don't do this with your safety. If brake parts are rusty throw them away and replace with new or rebuilt.

[mopar jack]

Had this problem a couple of times on my old Mopars. Usually happens when the MC goes bad and leaks causing the safety valve to close and after replacing the MC the safety valve would be stuck because it hadn't moved in years. So I had to replace the valve.