I recently purchased a 1992 F-350 CrewCab L.W 4X4, 460, E4OD, 3.55L, has 108,000 actual miles has never been worked in its life. My problem first started with a rear axle seal leaking, had my Chief mechanics do a rear brake job on it seals, wheel cylinders, brake shoes, turn drums, change oil in rear axle also the full rear brake job. The front brakes still have good pads a little pulsating in brake pedal not bad for a big truck. The brake pedal seems to fall to the floor very fast, so I replaced the master cylinder with a new one, it still doesn't stop the truck very quickly with out standing on it all the way kinda of scarey and it keeps dropping the pedal to the floor, brakes have been bleed several times. They won't pump up like if it was a weak master cylinder, even though it has a new one on it. Would it be a bad brake booster? I pulled the vaccum hose off and it had good vaccum also.

I just want good brakes on it like my 1995 Lightning has stop on a dime!!!

 

is power booster leaking?

is the rabs been checked out?

was master cylinder a quality part?

were the fronts bled at the same time?

 

Sounds like you still have air in the system. A bad booster can give a hard pedal needing a lot of force to apply the brakes, it won`t send the pedal to the floor. Keep bleeding it in the correct sequence and don`t forget the RABS valve block on the left side frame rail.

 

booster is not leaking.....

bleed at all 4 corners.......

best master cylinder Auto-Zone had....

what is rab?

 

I will bleed them again....when do you bleed the rabs valve? I know its LR, RR, LF, LAST RF.

 

Apparently Ford say to bleed the RABS after the two rear wheels. However when doing mine I bled it first of all. If you have a helper it helps if you close each bleed screw before letting pedal up, then open again for the next pedal stroke.

 

Thanks for the help.......I need my hauler to stop right!! My wife has been complaining about it!! LOL!!