One wheel locking up

I am having a problem with one wheel, rear left, locking up when I even lightly apply the brakes. Sometimes prior to the wheel locking up, I hear a clunk sound similar to metal hiting metal - although it doesn't always happen. It only happens after a cold night or when it is driven in the rain.

The Jeep is garage kept and the breaks have been checked atleast 4 times by 2 different mechanics. Below is the vehicle specs that I can remember off my the top of my head. Thanks in advance for any help.

1989 Jeep Wrangler YJ 4cyl Manual 5sp 4x4

You said brakes have been checked; have the rear shoes been replaced recently, or has this problem always been with you? Check for any leakage around the rear wheel; if brake fluid gets on the shoes it could cause your problem.

Also, check the right side. Make sure the shoes are tight enough on that side; if they're not adjusted to be tight enough to work, all the braking will be done on the left, and the left will skid.

Hope this helps...