I Have a 98 Laramie 360 4x4. My rear brakes lock up when I apply brakes hard???
What does that mean?

 

either the praportioning valve is messed up or your rear brakes maybe adjusted a lil too tight, climb under there and turn the adjuster back a couple clicks see if it goes away.

 

i had the same problem and i found out that one side of the brake pads came off of one of the shoes. replaced them both and havent had a problem since

 

Worn, broken, old springs!? Fluid contamination!? Mileage? The springs don't last forever. If they have never been replaced, do it. You know, the only real way to find out is open 'em up and see if there are any obvious abnormalities. These are just things to check while you're in there.
WC

 

Thanks for your responses. I will try taking the rear brakes apart tomorrow.

 

I have the same thing but I just changed the position of the lower spring and adjusted the heck out of them. I think they are a little over adjusted now. That's an easy thing to correct without pulling your wheels.