92 f150 brake problem
 

It is my brothers truck I use it sometimes to haul things. It just started happening 2 days ago, but the back brakes lock up now. I drive it normally empty not full and just sometimes not all the time, when I start to stop the back slides out mostly on the left side. What do you guys think it might be? I have checked the brakes they look fine, brake fluid was flushed recently, the ABS does not come on when this happens.

if the truck has drum brakes you might need to adjust the rear shoes inward also make sure your shoes arent swollen with brake fluid.

Thanks for the reply I just adjusted them today. My friend told me that you should be able to spin the wheel and it make 1 rotation for the best adjustment is that true? I never adjusted drums before.

Sometimes in order to make a worthwhile suggestion, I usually ask for more information.
Was there any special reason for flushing the brake fluid system?
Was any other work done on the brakes before you noticed this problem?
Drum brakes can sometimes overadjust and cause dragging brakes on that particular wheel. Don't overlook the part that the right rear wheel may not be doing its share of the work. There are a few reasons for brakes to "grab" and as noted by the previous post soaked linings can be one of the causes.
Also it was a common problem that the parking brake cables were causing the brakes to grab if the cable on that side is frozen and can't release completely.