[burninrubbah617]

I have an 87 Chevy caprice and every time I drive the car for the first five minutes whenever I slightly touch the brake pedal the rear wheels lock up. Would replacing the old drums with new ones solve my problem

[66GMC]

I'd suggest taking those drums off and doing a visual inspection.

My hunch is that you'll find a leaking seal(s) and have gear oil all over the shoes and hardware.

If everything is clean, have a good look at how the friction material is attached to the shoe. On bonded type, the glue will let go if not "burnished" properly after being installed. On rivetted type, look for cracks in the friction material or missing rivets ... either way ... I guess you're looking for attachment failure.

Also, I've had a couple of Fords that tend to get grabby rear brakes ... usually on very damp days when the vehicle has been sitting for a few hours.
Dragging the brakes (lightly applying the parking brake) for about 1/2 a block heats them up and dries them out, and they're fine until next time.

[poncho62]

Chances are the wheel bearing seal or wheel cylinder is leaking, causing fluid to get on the shoes. It then dries up once heated a bit.