Originally Posted by Noam Zane

The cantilever's springs are directional and it seems you have the front ones mixed up. When the canti is pulled toward the rim the spring coils should contract not expand, make sure of this.

I think I understand what you mean by this, and the springs are contracting as they pull the pads toward the rim. In fact, they pull the pads all the way to the rim. I tried putting these brakes on the rear, and they did the exact same thing on the rear.

The rear is a question of balancing the spring tension. After you have sorted out the left/rightedness of all four springs try switching one of the front with one of the rear springs.

I'm talking the left/right hand of each brake looking head-on at it so the F/R spring swap would be diagonal.