Brakes brutal when cold

[EricS]

When taking the car off the garage and for a few hundreds meters, a simple , very light pressure on the brake pedal makles a brutal stop. After a few strokes, it becomes "normal".
Pulled front left wheel to pull off the drum (and discovered the nuts were backward !) but it was locked. So it will work for this week-end trip but I guess I wil have to attend it.
What can make the brakes so brutal?
And what is the spring all around the drum?

[70 sublime]

Think you should find front and back wheels have left threaded nuts on left side and right threaded nuts on the right side of Mopars of this era 

[John_Kunkel]

Condensation/moisture will make the brake dust in the drums cause the brakes to grab; after a few brake cycles the heat will dissipate the moisture.

[A383Wing]

you also could have wheel cylinders seeping fluid on the brake shoes & drums

[b5blue]

The spring around the drum helps cooling.

[A383Wing]

The spring around the drum helps cooling.

It's for dampening harmonics

[b5blue]

WUT? 

[John_Kunkel]

Turn a drum in a brake lathe without the spring and listen to it sing. 

[EricS]

No visible leak on the brakes. I will pull off drums later and try to clean them and further inspect.