I've got a '67 that it completely stock with power drum brakes. When I depress the brake pedal, there is very light braking but as I push the pedal down further, at a certain point it's like I'm hitting the brakes really hard. Not quite a lock-up situation, but it definitely sends you forward in the seat. Another way to put it is it feels like the an on/off situation with almost no in-between to modulate the braking of the car. I've installed a fresh rebuilt power booster, checked and double checked the adjustment of the brakes shoes. Any suggestions or trouble shooting ideas would be greatly appreciated. Thanks in advance. Jeff

New shoes, freshly turned drums, will do it all the time until the shoes get broken in to the drums.

Drums are smooth, but look closely with high power magnifying glass and the surface will show 'curls' from the cutting tool. Until these get worn down by the shoes, these curls catch the shoes.

Also, some oil on the shoes, whether from the hands, alittle brake fluid, or the preservative on the new drums preventing them from rusting during storage contaminates the shoes, thus a sticky surface.

I could be in left field.