Maybe check on the Sram website, their downloadable instructions for the BB7s will give you a great heads up.
I *think* from what you've been saying above, that when your pads actually hit the disc, the angle between the top of cable arm and the cable will be more than 90 degrees. For good performance, the cable and the cable arm should be at 90 degrees to each other when the pads hit the disc.
If you're using the cable pull adjuster or the barrel adjuster on the levers, you will lose this position.
Also, like any cable brake, if your cables have a lot of friction (old, dirty or kinked cable outers) the brakes will feel terrible. I just ran basic Shimano outer for the full length with my BB7s, filled it with some waxy dry lube, and had no problems.