1998 Ford F-150 4x4 Noticed today my brakes lock my rear tires up only when I need to stop quikely or when I push a little hard I'm good on brake fluid. Looked around on brake lines a little didn't see any leaks and checked after driving all day after topping the brake fluid off (it was a tab low) and still at same as when I topped it off.I just got truck two days ago and has done it just noticed when I use brake it feels hard then goes soft but doesn't go all the way to the floor. Did the owner I got it from possible not bleed the brakes and maybe need redone by starting with the front to the back(bleeding)? No rubbing or grinding as if bad pads or rotors and seems to be no pulling as if there's a caliper locking up and not releasing. Feels like my mothers car after changing her brakes and didn't get them bleed it's just not as bad and doesn't go to floor.........so try to bleed them???? Thanks in advance!!!!

 

Yes, bleed them. Sounds like therr is air in the line. Also check caliper pistons to make sure they are not hanging up also.

 

If the rears are locking up you may have a bad wheel cylinder. Brake fluid on the pads will do that if the wheel cylinder is leaking. If it has 4 wheel disc it could be the proportioning valve is bad, putting too much pressure to the rear brakes.