The truck... 01 1500 qc 4x4, 5.9, auto, 85K miles, no mods. The problem... The rear brakes like to lock up with minimal pedal effort sometimes. Its not an every day thing, and not just after its been sitting a while, its completely random. Happens only at low speed. Pads and shoes are good, everything looks ok in the drums. Sometimes it feels like it takes more pedal effort to stop from speed, then when the speed gets low enough it locks hard enough to get the rear tires to skid on dry pavement. So, where the heck do I start? Anyone else ever have this problem? I experienced it before on a 3500 2x4 but we didn't do maintnance on it (was a GSA vehicle) and the shop never did get the problem to go away that I know of. My initial thoughts are something wrong in the front brakes, maybe sticky calipers so more force is required to move them, in turn putting more force to the rears causing the lock. Only problem with this theorie is when traveling slow it takes so little pedal effort to lock em up. Maybe a preportioning valve problem? I just spent the last hour searching and reading brake threads here, but its possible I missed something, so if its already been adressed please point me in the right direction. I did find one thread mentioning rear brake lockup from jan of 06, but it had no replies. I'd prefer to not start randomly throwing parts at it till I by chance hit the right spot. Thanks.