My ebrake on an 04 screw hold the vehicle on an uphill, (stops from going backward) but not in forward (downhill). I figure this has something to do with the physics of the brakes (closer to the end of the vehicle that is facing downhill). BUT, I am thinking this is not necessarily the way they should be set. Any ideas..and are they adjustable...on an old Ranger there was a simple dimpled wheel you could add tension or release as need be.
cheers,
(disc brakes...)

 

Your 2004 F150 uses a drum-in-hat (DIH) parking brake design. So called because the rotor looks somewhat like a top hat, with the parking brake being a small drum brake mounted inside the "hat". It has a manual adjustment and you probably need to tighten it a small amount. Be careful not to over-tighten it as you don't want the brake to rub while driving.

As to why it holds better in reverse... the direction of the force can help "self-energize" the brake - the friction force amplifies the clamping force. This is most likely why you notice a difference in the two directions. Being on the uphill or downhill side doesn't change anything.

Carefully adjust them out a bit and you should be ready to go (or stop I guess )

 

is this easy to get at...or do I have to remove the wheel(s)?

 

You have to remove the wheels... unless you have really really small hands...