No. My brakes never lock, not even for an instant. That said, I am very light on my brakes as a rule. I do hit them hard when I need to.

The guy that mentioned the drums expanding from heat keeps coming to mind as the most rational explanation but I've never experienced such so it's still hard to accept.

Vehicles that sit a lot and vehicles exposed to salt have glitchy brake issues.

Did you look at how the adjusters actually work. The little cable lifts the arm and if it goes high enough it clicks the adjuster a notch coming back down. Maybe something is positioned wrong or too short or something so the arm lifts too high sometimes. Relating it back to towing doesn't add up.

There are 12" brakes and 12 1/8" brakes, or something like that. Any chance of some wrong parts?

 

Ya. I am generally light on brakes to. Dont ride them or wait til last second to apply them. Pads are correct. Even put them up to old pads to make sure they are correct. Cables for the emergency brake havent been messed with. So they are what has come with the truck from Ford. I hear you about not adding up to towing. But so far it has only done this when pulling trailer. So i have to think about that too when trouble shooting. I went over everything last night. All is correct parts and in correct locations. I know how the emergency brake works. And all is operating as it should. I have a theory about what might be causing this and i shoukd know by tonight or tomorrow if im right.

 

I even spoke with mechanic from Ford last night that works with a friend of mine at a local dealer here. Went over how everything is supposed to be installed and i have everything right. Im not an idiot. I have done many brake jobs over the years and a few drum setups with never any issues. I think i know whats going on. I will know more tomorrow

 

I'm confident you will get it. It's not rocket science but there are lots of little things that can be problems. Aren't you glad you're not fixing it for someone else as a paying job? It could eat your lunch.

 

Aint that the truth... lol

 

I read these threads and try to learn things. I searched for this issue and found this. No idea if it will help but here it is anyway. Sandy


Remove your brake drums (Caution do not touch your brake pedal in this test with drums removed)
You will have to tear down the suspect rear drum brake side. If you are getting one side that is hotter after driving then the other or notice more brake dust on the inside of your wheel rim then that would be your suspected side that has the seized parking brake cable. Also look at your thickness of friction material on the shoes edge. The shoe that is worn with a taper 3 or 4 inches on the one shoe would indicate that the cable is fouling up the shoes movement. Check the forward facing shoes. Use a vernier caliper or micrometer if you have one to measure shoe thickness at the top and bottom of each shoe. If you get a big difference in measurement then this is your problem. (example, including metal shoe thickness, top = 0.183, bottom = 0.154)
Tear down only one side leaving one side for reference, refer to your service manual for you exact year, make and model.

At this point you should have the parking brake cable protruding through the backing plate at the bottom around the five o'clock position. Note the return spring that covers the end of the cable where you removed the parking brake lever that is attached to the rear brake shoe. Take a tape measure and measure the length of the spring.

Now push in your "parking brake pedal" inside the truck on the drivers side all the way and release it with the release.

Go back and measure the end of the parking brake cable spring length. If its bad you will see the spring on the cable still compressed and short in length, this is seized. A different measurement will also indicate the spring on the end of the cable can't over come the internal friction in the parking brake cable sheathing to return to a normal position.

Remove and replace bad parking brake cable, follow service manual procedural for this.

 

Thanks for the post. Its not the cable. Its been doing this and i havent set the emergency brake on purpose the last few weeks to just see if the brakes would still drag without me setting emergency brake, and they still drag.