I have the S13 240SX calipers on my car, and have been having the same issues with my E-Brake. I'm going to swap in a 79 master, and replace all the fluid. Hopefully this will resolve my issue. I think I will also try to put a spacer or washer between the cable bracket and the e-brake cable, to see if this gives me more throw.
I have tried to tighten up the rod assembly, but I feel that it puts to much pre-load on the caliper. I'll be re-doing this tomorrow, so I'll let you all know how it works out.