Ok so i have a 1979 Mustang and im having a really annoying brake problem.
The brakes start to lock, like if someone is putting full power on to the brake pedal.
The brake pedal gets really hard and the brakes just get stuck.
it does it after driving it for only like 5-10 minutes then goes away when you turn it off and wait about 3 hours.
Its starting to get worse and worse every time.
What can this stupid crap be??

 

when it happens jack the car up and try and spin the wheels and see which ones are hard to spin...like front or rear??? from their it could have a bad caliper or wheel cylinder or rear shoes whose backing could of come loose jamming up rear brakes if prob is in the rear......you need to narrow down the prob to front or rear or a wheel, it could also have a bad master cylinder, but usually pedal goes to the floor and or is real spongy if such is the case

 

^^^Like a poet.

 

I knew i forgot something.
its only the front ones, it gets so bad that i cant even move the car, and the back wheels start to spin.
the previous owner had the mastercylinder repaired or he got a rebuilt one and put it in, forgot which one.
When the brakes are normal the pedal does kind of feel spongy but it stops fine.
Oh yeah and it started to leak fluid on both sides in the front.

 

IF IT'S JUST THE FRONT when the wheels are locked up pull a wheel and open a bleeder..if the wheel then frees up, there is a restriction like a bad brake line or a bad portion/circuit of the master cylinder and by circuit I don't mean electrical I mean hydraulically.....however if opening a bleeder doesn't release a wheel = most likely bad calipers, perform same test operation for both sides

 

Is it both fronts locking up?

 

It sounds like you may not have enough freeplay in the master cylinder. Next time it locks up loosen the nuts on the master cylinder a little and see if that frees it up. If it does you need to adjust the rod that goes from the master cylinder into the booster.

 

Ok thanks a lot guys.
the car actually got stuck at a gas station and i just got it back home right now.
im just glad i got it home, the gas staion is in the ghetto so i was worried.
Ill have to check all that tommarow.
Thanks again.

 

if that were the case the prob would be present all the time and not go away after sitting.......since it reappears after a short while of driving there is most likely a restriction somewhere that bleeds back to the master cylinder after sitting....kinda like a plugged drain...after sitting a while it'll often slowly drain if it's not totally restricted....anyway check what is mentioned and let us know

 

Did it have this problem before the rebuilt master cylinder wan installed?